Animal The Definitive Visual Guide

FROGS AND TOADS 449

Reproduction AMPLEXUS

Once males and females have located one another (see facing page), mating Amplexus may take place on land or in water—
can occur. The male adopts a position known as amplexus, in which he clasps these tree frogs (right) mate in the branches
the female from above (see right). Fertilization takes place while the pair are of trees. Depending on the species, the
in amplexus, which may last for a period ranging from a few minutes to several male may clasp the female just behind
days, depending on the species. In all but a small number of species, fertilization her front limbs or just in front of her back
is external, the male shedding sperm onto the eggs as they emerge from the limbs. In many species, males outnumber females
female. Each species has a characteristic pattern of egg production and uses in breeding groups, and males in amplexus are often
a specific type of site for egg deposition. Eggs may be produced singly, in attacked by rivals seeking to displace them.
clumps, or in strings. The female usually places them in water, because their
development can occur only in moist conditions. Eggs may be dispersed into

the water, where they may float or sink, they may be
wrapped around vegetation, or they may be glued to
plants, logs, or rocks.

EGGS

The number of eggs produced by a
female varies greatly among species,
from less than 20 to many thousand.
The eggs of the European common toad
(left), which are suspended in long strings
of jelly, are wrapped around the underwater
stems of aquatic plants.

Defense AMPHIBIANS

Frogs and toads typically lack weapons, such as large teeth
or claws, that they can use to defend themselves. Most rely on
being able to escape by jumping, usually toward open water. Many
produce secretions from glands in their skin that make them
distasteful or poisonous, sometimes lethally so. Others rely on
being well camouflaged. In general, tadpoles lack defenses and are
eaten by various predators, notably fish and the larvae of insects,
such as dragonflies. Being produced in large numbers means that
at least a few survive.

WARNING COLORATION

The poison-dart frog (left) has
had to evolve highly poisonous
skin secretions because many of
its predators (including snakes
and spiders) have evolved a resistance
to milder toxins. Many species that are
distasteful or toxic are vividly colored, which
acts as a warning to predators.

Movement CAMOUFLAGE
Most frogs and toads are active only at
Frogs and toads move in a wide variety of ways. night and remain entirely motionless by
Most toads are ground dwellers and walk, run, day. Species such as this leaf frog (right)
or hop over the ground; few are able to leap large have skin that is colored to match their
distances. Leaping is rarely used for moving from background and are patterned in such a
place to place but is primarily a means of escape
from predators. Not all frogs and toads jump: way that their outline is broken up.
many have back limbs adapted for other types of
movement, such as swimming, climbing, and (in legs straightened in mid-air
a few species) gliding. Burrowing is important for to form streamlined shape
many species, enabling them to hide during the
day, or for many weeks or months when it is too eyes narrowed or
cold, hot, or dry for them to be active. They may closed for protection
simply push their way under rocks or logs, or into
piles of plant debris, or they may be able to dig CLIMBING LEAPING
deep into the ground. Some desert species can
survive being buried for up to 2 or 3 years. Some frogs (such as the Frogs and toads
European treefrog, left) launch themselves
spend their entire life in into the air with an explosive burst
tree canopies or among of energy from their long hind legs.
other types of vegetation. On landing, the front legs are pushed
Their long, slender limbs forward to cushion the impact.
enable them to jump or
straddle gaps between
branches, while the
adhesive disks on their
digits allow them to
climb vertical surfaces.

450 FROGS AND TOADS

Ascaphus truei Leiopelma hochstetteri Bombina orientalis and lifts its limbs over its head to
display this vivid coloration. It also
Tailed frog Hochstetter’s frog Oriental fire-bellied produces a distasteful secretion through
toad its skin. The Oriental fire-bellied toad
Length 1 – 2 in Length 11⁄2 – 2 in lives in mountain streams in coastal
Location S.W. Canada, (2.5 – 5 cm) Location New Zealand (3.5 – 5 cm) Length 11⁄4 – 2 in areas, and hides under rocks and logs in
N.W. USA Habit Mostly terrestrial (North Island) Habit Mostly terrestrial (3 – 5 cm) winter and during dry spells. The male
Breeding Spring to Breeding Summer Habit Mostly aquatic calls to attract a mate. The female lays
season fall season Breeding Spring and small clutches of large eggs under
Status Least concern Status Least concern season summer rocks in streams.
Status Least concern
Location E. and S.E. Asia bright green and
black back

This small green, brown, gray, or reddish The most distinctive feature of this
amphibian is the only aquatic frog that squat, slightly flattened toad is its
breeds by internal fertilization. The bright red underside with black
unique “tail”—found only in males—is mottling. When threatened, it
an extension of the cloaca, and is used arches its back, flattens its body,
to insert sperm into the female’s cloaca.
AMPHIBIANS Females lay strings of eggs in cold This squat brown frog—an inhabitant Pipa pipa and slow-moving water, the Surinam
mountain streams, attaching them to of damp ground—is one of just 4 toad is highly adapted to an entirely
the underside of rocks. The tadpoles species of frogs that are native to New Surinam toad aquatic existence. Powerful hind limbs
take 2 years to mature, and have Zealand. Its eggs, which are enclosed aid swimming, sense organs along its
suckerlike mouths that enable them in large, water-filled capsules, develop Length 2 – 8 in sides detect vibrations in the muddy
to cling to rocks in fast-flowing water. into nonfeeding tadpoles that stay (5 – 20 cm) water, tentacle-like projections on its
within the capsule until they mature. Habit Wholly aquatic fingers feel for prey, and upward-pointing
rough skin When they are fully developed, they Breeding Rainy season eyes see above the surface. This
emerge as froglets. Hochstetter’s frog season toad exhibits unusual mating and
dark stripe is still abundant in some localized Location N. South America Status Least concern breeding patterns: the male clasps the
through eyes areas, but 2 other New Zealand female from above, and the pair turns
species are now very rare, and The Surinam toad is gray above and upside down repeatedly. The eggs are
confined to offshore islands. paler below, with a flattened body released, fertilized, and trapped in the
and flat, triangular head. Like other space between the male’s belly and
members of the family Pipidae, it lacks the female’s back. They are then
a tongue. An inhabitant of turbid, muddy, absorbed into the skin on the female’s
back, where they develop in capsules
and emerge as miniature frogs.

Xenopus laevis SENSE ORGANS

African clawed toad This toad has a line of white
“stitch marks” along its sides. These
Location C. and Southern Length 21⁄4 – 5 in contain special sense organs that
Africa. Introduced to USA (6 – 13 cm) detect vibrations, helping it to locate
and Europe Habit Mostly aquatic food and predators in murky water.
Breeding Rainy season
season 3 fingers on each
Status Least concern forelimb

With its flattened body and large, line of “stitch
marks” on
webbed feet, the African clawed toad each side

(also known as the platanna) is ideally muscular
hind limbs
suited to a bottom-dwelling lifestyle in

lakes and ponds. Like its close relative Alytes muletensis bred in captivity are released into
suitable habitats on Majorca. It
the Surinam toad (see right), it has Majorcan midwife has a yellowish or pale brown body,
toad with dark mottling. Both the males and
eyes and nostrils positioned females call to locate mates. The female
transfers a batch of eggs to the male,
on the top of its head, and who carries them until they are ready to
hatch. Their tadpoles grow very large,
camouflaged skin to and little growth occurs after
they become adults.
protect it
blotches on skin
from herons Length 11⁄2 – 13⁄4 in
(3.5 – 4.5 cm)
and other Habit Mostly terrestrial
Breeding Spring and
predators. During season summer
Status Vulnerable
the breeding season,

females lay numerous very small

eggs, attaching them to various Location Balearic Islands
(Majorca)
underwater objects. This species is

often raised in laboratories for

teaching and research.

clawed
toes
FORELIMBS WITH FINGERS One of the world’s most rare toads, this
The small forelimbs possess 3 fingers, which tiny species (also known as the ferreret)
are used to shovel invertebrates and small has been the subject of a very successful
fish into the mouth of this voracious feeder. conservation program, in which animals

FROGS AND TOADS 451

Alytes obstetricans male during mating. The male then Rhinophrynus dorsalis makes it easy to burrow, emerging only
wraps these strings of eggs around his after heavy rain. Adults breed in ponds,
Midwife toad legs, sometimes carrying 2 strings laid Mexican burrowing and the males have internal vocal sacs
by different females. Once the eggs are toad that they use to call to females. After the
Length11⁄4 – 2 in ready to hatch, the male deposits them eggs hatch, the tadpoles feed by filtering
Location W. and (3 – 5 cm) in ponds and pools. This toad is small Length 21⁄4 – 31⁄4 in food from the water, using barbels
C. Europe Habit Mostly terrestrial and plump, with short legs and sandy, (6 – 8 cm) around their mouths.
Breeding Spring and pale brown, or gray skin, with darker Habit Terrestrial/
season summer spots. It inhabits woodland, gardens, Burrowing red stripe
Status Least concern drystone walls, sand dunes, and rock Breeding Rainy season on back
slides, hiding in crevices in winter and season
during dry periods. Active at night, it Location S. USA to Central Status Least concern black
feeds on invertebrates. Males attract America body with
females by calling from a crevice red spots
The midwife toad is notable for its or burrow, making a distinctive, With its bloated body, pointed snout, and
highly unusual method of breeding. high-pitched “poo-poo” sound. small legs, this unusual-looking toad is
The female lays large, yolk-filled eggs adapted to a life spent underground. It
in strings, which are transferred to the rough skin lives in low-lying regions where soft soil

Scaphiopus couchii One of 7 similar species, all from North
America, this yellow or yellowish green
Couch’s spadefoot toad, with darker mottling, is a classic
example of an amphibian that survives
prominent eyes Length 21⁄4 – 31⁄2 in drought by burrowing underground.
with vertical (5.5 – 9 cm) Like its relatives, it has spadelike black
pupils Habit Mostly terrestrial ridges on its hind feet, which it uses
Breeding Spring and to dig its way 31⁄4 ft (1 m) or more into
Location S. USA, Mexico season summer loose, sandy soil. Once below ground, it
Status Least concern encases its body in a watertight cocoon
made by shedding several layers of
eggs powerful forelimbs large eyes with skin, and then remains dormant, waiting AMPHIBIANS
carried by for digging vertical pupils for rain. When rain does fall—sometimes
male many months later—the cocoon breaks

down, and this toad makes its
way to the surface to breed.

Pelobates fuscus Megophrys montana

Common spadefoot Asian spadefoot
toad
Length 23⁄4 – 51⁄2 in
Length 11⁄2 – 31⁄4 in Location S.E. Asia (7 – 14 cm)
(4 – 8 cm) Habit Mostly terrestrial
Habit Mostly terrestrial Breeding Rainy season
Breeding Spring season
season Status Least concern
Status Least concern
Location C. and E. Europe,
W. Asia

This plump, variable toad has a pale Pelodytes punctatus parsley. Like most frogs, it is active at
“spade” on each hind foot, enabling it night, spends winter and dry spells
to dig backward into the soil. It lives Parsley frog buried underground, and feeds on
in sand dunes, and in cultivated insects and other invertebrates. During
areas, preying on insects and other This tropical toad is one of the world’s Length 11⁄4 – 2 in the breeding season, males call out from
invertebrates. When threatened, it most effectively camouflaged (3 – 5 cm) underwater to attract females, who call
squeals, inflates its body, and raises itself amphibians. It lives on the forest floor, Habit Mostly terrestrial back. Females lay their eggs in broad
up to appear larger. It emits a garliclike mimicking dead leaves. Its brown Breeding Spring strips in ponds. The tadpoles sometimes
odor, possibly to deter predators. color and its shape are remarkably season grow to be larger than the adult frogs.
leaflike, with a sharp snout, pointed Status Least concern
“horns” over its eyes, and folds of skin Location W. and S.W. prominent eyes
that look like leaf edges. Female Asian Europe with vertical pupils
spadefoot toads lay their eggs under
rocks in streams. After hatching, The small, agile parsley frog lives in long
the tadpoles hang vertically from the damp, vegetated habitats near ponds. limbs
water’s surface, and feed on very It has an unusual method of climbing,
small organisms using their large, which involves clinging onto vertical
umbrella-shaped mouths. surfaces such as trees, rocks, and walls,
using its belly as a kind of suction pad.
Its name derives from the green flecks
on its pale skin that resemble chopped

452 FROGS AND TOADS

Notaden bennettii and emerges to feed and breed when Limnodynastes peronii the female. During mating, the pair
it rains. This toad feeds on ants and make a floating foam nest in which
Holy cross toad termites, and produces a sticky, Brown-striped frog 700 – 1,000 eggs are deposited. The
defensive secretion when handled. Its eggs hatch quickly, and the tadpoles
Length 11⁄2 – 23⁄4 in tadpoles develop in temporary pools. Length 11⁄4 – 21⁄2 in develop very rapidly.
(4 – 7 cm) (3 – 6.5 cm)
Habit Mostly terrestrial Habit Mostly terrestrial powerful hind legs
Breeding After heavy Breeding Spring and
Location E. Australia season rain Location E. Australia season summer
Status Least concern Status Least concern

Named after the crosslike pattern of short, Also known as the Australian grass
warts on its back, this small, globular stumpy legs frog, this long-limbed amphibian,
toad belongs to a family of over with dark longitudinal stripes along
43 species that are found only in its body, lives in and around swamps,
Australia. Like many of its relatives, feeding at night on insects and other
it spends dry periods underground, invertebrates. During winter and dry
spells, it buries itself underground. The
male makes a clicklike call to attract

Crinia insignifera temporary swamps that form after Uperoleia lithomoda Sechellophryne gardineri
winter rain, preying on insects and other
Sign-bearing toadlet invertebrates, and spends dry periods Stonemason toadlet Gardiner’s
underground. During the breeding Seychelles frog
Length 1⁄2 – 11⁄4 in season, the male calls to attract a mate. Length 1⁄2 – 11⁄4 in
Location S.W. Australia (1.5 – 3 cm) Females lay about 60 – 250 eggs at a (1.5 – 3 cm) Length 3⁄8 – 1⁄2 in
Habit Mostly terrestrial time in water, either singly or in clumps; Habit Mostly terrestrial (1 – 1.5 cm)
Breeding Winter the eggs fall to the bottom of the pond. Breeding Winter Habit Wholly terrestrial
season season Breeding Rainy season
Status Least concern darker spots Status Least concern season
or stripes Status Endangered

AMPHIBIANS Location N. Australia

The sign-bearing toadlet is a small Location Seychelles
Australian frog with a slender body
and limbs. It is gray to brown, and long digits The clicklike courtship call of this small,
often has a dark triangular patch squat frog sounds like 2 stones being
between its eyes; its skin may be hit together, hence its name. It is dull
smooth or warty. This frog inhabits brown or gray, with a gold line or row of
patches along each side of its body,
Mixophyes carbinensis Pseudophryne corroboree short limbs, and a horny tubercle on its
hind feet that enables it to dig into
Carbine frog Corroboree frog the soil. It spends dry periods buried
underground. The female lays eggs
Length 21⁄4 – 3 in Length 1 – 11⁄4 in in clumps that fall to the pond floor. This tiny, creamy white to yellowish
(6 – 7.5 cm) (2.5 – 3 cm) green frog is notable for its unusual
Habit Mostly terrestrial Habit Mostly terrestrial wartlike glands breeding pattern. The eggs, which
Breeding Spring and Breeding Summer on skin are laid in clumps on the ground, are
season summer season guarded by the male and hatch into
Location N.E. Australia Status Least concern Location Australia Status Critically froglets instead of tadpoles. The froglets
(S.E. New South Wales) endangered crawl onto their father’s back and
remain there, glued on by mucus,
This critically endangered animal, until they have used up their yolk
also known as the corroboree toadlet, and their legs are fully developed.
is one of Australia’s most colorful
amphibians. It lives in moss-covered Heleophryne purcelli toe tips give it a strong grip on slippery
bogs in the Australian Alps, and lays
its eggs in the moss rather than in water. Cape ghost frog rocks and boulders. During the breeding
The reason for its vivid colors—yellow or
yellow-green, with black stripes—is season, males develop tiny spines on
unclear: unlike most brightly colored
amphibians, it does not have toxic skin. their bodies. The tadpoles have large,

short, unwebbed digits Length 11⁄4 – 21⁄4 in suckerlike mouths to attach themselves
(3 – 6 cm)
Habit Mostly aquatic to rocks.
Breeding Summer
This species was described in 2006 on season flattened body green, yellow, or brown
the basis of specimens collected from Status Least concern coloring with mottling
Mount Lewis in the Carbine highlands of
Queensland—in an area designated Location Southern Africa
as a World Heritage Site. It belongs (Cape region)
to a genus of large ground-dwelling
frogs restricted to eastern Australia The Cape ghost frog is ideally suited smooth skin
and New Guinea, and lives to its aquatic lifestyle. Its long legs and
in montane rain forest near webbed hind feet enable it to swim in
streams and pools. Males fast-flowing streams, and its flattened
call during the breeding
season from the leaf-litter floor.

FROGS AND TOADS 453

Ceratophrys cornuta HUNTING BY AMBUSH Telmatobius culeus

Surinam horned The Surinam horned frog catches Titicaca water frog
frog other frogs, lizards, and mice
using a sit-and-wait technique. Length 31⁄4 – 4 3⁄4 in
Length 4 – 8 in It partly buries itself in soft ground, Location South America (8 – 12 cm)
(10 – 20 cm) sometimes with only its eyes (Lake Titicaca) Habit Wholly aquatic
Habit Mostly terrestrial projecting above the surface, Breeding Summer
Breeding Rainy season and then waits for animals to season
season pass by. Like other amphibians, Status Critically
Status Least concern it is triggered into action by endangered
movement. Once its prey is within
Location N.W. South range, it bursts out of hiding,
America immobilizes its victim with its
fangs, and then swallows it whole.
This frog has several adaptations
This bulky and intricately patterned hornlike STOCKY BUILD that suit it to a life in the cold, oxygen-
frog is a formidable hunter, with an projections The Surinam horned frog is a massive, impoverished waters of Lake Titicaca.
exceptionally large mouth. It ambushes plump-bodied frog, with a huge head and It has long hind legs with fully webbed
its prey and, if threatened, defends itself wide hind feet for swimming, and very small
ferociously, using its large, sharp teeth. mouth a very wide mouth. It has conspicuous lungs that enable it to dive. Due to the
It has a well-camouflaged body, hornlike projections over its eyes. small size of its lungs, it relies mainly on
relatively short legs, and a “horn” oxygen taken in through the skin. This
above each eye. Males are slightly uptake is increased by the extensive
smaller than females and, in folds in its skin, which increase the
the breeding season, they animal’s surface area, and the presence
produce a mating call that of numerous blood vessels and red
sounds like cattle lowing. blood cells.
Females lay up to 1,000
eggs, wrapped around folds on
aquatic plants. Unlike skin
most tadpoles, Surinam
horned frog tadpoles are AMPHIBIANS
predatory from the moment
they hatch, and attack the
tadpoles of other frogs and
even each other. They have
large, horny beaks and
muscular jaws.

Eupemphix nattereri Engystomops pustulosus Leptodactylus pentadactylus to the American tropics. It is yellow
or pale brown, with dark markings,
Cuyaba dwarf frog Tungara frog South American long legs, large eyes, and conspicuous
bullfrog external eardrums. The male has
Length 11⁄4 – 1 1⁄2 in Length 11⁄4 – 11⁄2 in muscular forearms, with a sharp black
Location E. South America (3 – 4 cm) Location Central (3 – 4 cm) Length 31⁄4 – 9 in spine on his thumbs, which he uses to
Habit Mostly terrestrial America, N.W. Habit Mostly terrestrial (8 – 22 cm) fight off other males. The female lays
Breeding After heavy rain South America Breeding Rainy season Habit Mostly terrestrial eggs near water, depositing them in a
season season Breeding Rainy season foam nest that the male has created
Status Least concern Status Least concern season by whipping up mucus with his hind
Status Least concern legs. South American bullfrogs are
Location N. South active at night, feeding on insects and
America other invertebrates as well as other
small animals, and spend dry periods
The Cuyaba dwarf frog is characterized warty skin This powerfully built frog is one of the hidden under logs or underground. If
by the 2 black and white eyespots on its largest members of its genus—a group picked up, they emit a loud scream to
rear. When threatened, it inflates its body With its dark gray or brown warty skin, of 74 species that are mainly confined startle the predator into loosening its
and lifts up its rear end, displaying these this Central American frog resembles grip. The hind limbs of this frog are
false eyes to startle the predator. It can a toad. The male calls loudly to attract sometimes eaten by humans.
also secrete a distasteful substance from females, repeatedly inflating his large
glands near its groin to further deter its vocal sacs to produce a sound that smooth, pale
attacker. This frog has a plump, toadlike consists of a basic “whine” followed skin
body, with short limbs. It is mid-brown, by one or more “chucks.” The more
with marbled patterning chucks he makes, the more likely he
in darker and lighter is to attract a female; however, his call
shades of brown. can also attract predatory bats. The
female lays her eggs in floating foam
eyespots nests in temporary pools.

454 FROGS AND TOADS

Eleutherodactylus planirostris Bufo bufo IN SELF-DEFENSE Anaxyrus americanus

Greenhouse frog European common toad American toad

Location S.E. USA, Length 1 – 11⁄2 in Location N.W. Africa, Length 31⁄4 – 8 in Location E. Canada, Length 2 – 31⁄2 in
Caribbean (2.5 – 4 cm) Europe to C. Asia (8 – 20 cm) E. USA (5 – 9 cm)
Habit Wholly terrestrial Habit Mostly terrestrial Habit Mostly terrestrial
Breeding Summer Breeding Spring Breeding Spring
season season season
Status Least concern Status Least concern Status Least concern

One of Europe’s most widespread The European common toad has robustly built parotid gland
amphibians, the European common a large parotoid gland behind each body
toad is a robust animal with a warty eye, which exudes a distasteful
secretion to ward off predators.
or spine-covered skin. Its color If threatened, it often swells up by
ranges from brown or green gulping air, and stands on tiptoe
to brick-red, and females are to make itself look larger. Despite
generally substantially larger than its menacing appearance, it rarely
bites and is harmless to humans.
males, particularly in early spring,
when they are laden with eggs. At toad spends much of its time away
this time of year, males and females
congregate in ponds and, after pairing from water, feeding on insects, slugs,
up, the female lays strings of eggs
around underwater plants. and other small animals. It is mainly Like the European common toad (see
During the rest of left), the American toad has warty skin,
the year, this nocturnal, hiding by day under logs prominent eyes, and a large parotid
gland on each side of its head. It
This tiny frog—one of and in other damp places. warty or shows great variation in color, from
the world’s smallest—belongs to a spiny skin brown to brightly colored, and has
family of about 201 species that are a spotted chest. An adaptable animal,
AMPHIBIANS found throughout warm parts of the APPEARANCE
Americas. It is brown or tan, with darker This common toad it is found in all habitats, including
mottling or stripes on its back, and has large, copper- or gardens and mountains, and is
well-developed adhesive disks on its gold-colored eyes. During the active at night. During courtship,
fingers and toes. The greenhouse frog breeding season, the male
usually lives in wooded habitats, but develops pads on his front males produce a musical trill
also enters gardens. Like its many feet for gripping the lasting 3 to 60 seconds to
relatives, it lays eggs in moist places female. attract mates. Females lay
on the ground, that hatch directly eggs in long strings in ponds,
into fully formed frogs. wrapped around vegetation.

Pristimantis mutabilis gets its name from its ability to alter the Amietophrynus gutturalis Amietophrynus rangeri
texture of its skin radically. It can go
Mutable rainfrog from being smooth to being covered Guttural toad Raucous toad
in numerous spinelike protuberances
Length ⁄11 16 – ⁄15 16 in (tubercles) within a matter of minutes, Length 2 – 4 in Length 2 – 41⁄4 in
(1.7–2.4 cm) though the function of this transformation (5 – 10 cm) (5 – 11 cm)
Habit Arboreal is not known. Habit Mostly terrestrial Habit Mostly terrestrial
Breeding Not recorded Breeding Spring Breeding Spring
season tubercle season season
Location Northern Ecuador Status Endangered Status Least concern Status Least concern
Location Southern Africa Location Southern Africa

Discovered in 2013, this species prominent eyes This yellow or pale brown, spotted
from northern Ecuador is pale brown toad inhabits grassland and woodland
to grayish green, with dark patches close to rivers, streams, and ponds. In
on its upperside. It also has a thin cool and dry spells, it hides under logs
orange line running along each side or rocks, or in rotting vegetation. When
of the back. The mutable rainfrog cornered by a predator, it produces a
sticky, distasteful secretion through its
Pseudepidalea viridis urban areas. It spends winter and dry The guttural toad is found in a parotid glands. During the breeding
periods under logs, rocks, or buried in variety of sites that provide cover, season, males let out loud, harsh
European green toad rotting vegetation. Active at night, it feeds close to ponds, dams, and streams. “quacks” to attract females. Mating
mainly on insects. During courtship, the In urban areas, it can often be seen activity, such as calling and fighting, is
Location E. Europe, Asia Length 21⁄4 – 31⁄2 in male makes a high-pitched call. A female under streetlights at night, feeding extremely energetic, and males lose
(6 – 9 cm) European green toad may lay between on insects. However, it also preys on weight at this time of year.
Habit Mostly terrestrial 10,000 and 12,000 eggs at a time. other invertebrates and on flying
Breeding Spring and termites as they leave their nest. The large parotid gland
season summer green female is larger than the male, but
Status Least concern marbling warty skin
the latter has longer forelimbs.
This robust toad has pale skin with green warty skin Both sexes are pale brown with
marbling and red spots. It prefers sandy dark brown patches. The male
habitats in lowlands and dry places, but makes a deep guttural “snore”
is also found in mountain regions and in to attract a mate, and the female
lays eggs in water.

FROGS AND TOADS 455

Atelopus zeteki Nimbaphrynoides occidentalis Pedostibes hosii forest, and is active at night, feeding
on ants. The female lays numerous
Golden frog Western Nimba Boulenger’s Asian small eggs in strings in flowing water.
toad tree toad The tadpoles have suckerlike mouths
Length 11⁄2 – 21⁄4 in
Location S. Central (3.5 – 6 cm) Length 1⁄2 – 1 in Length 2 – 4 in that enable them to
America (Panama) Habit Mostly terrestrial (1.5 – 2.5 cm) (5 – 10 cm) cling to rocks.
Breeding Rainy season Habit Wholly terrestrial Habit Mostly terrestrial
season Breeding Spring and Breeding Rainy season prominent eyes
Status Critically season summer season
endangered Status Critically Status Least concern warty
endangered skin
Location W. Africa Location S.E. Asia
(Mount Nimba)

This vivid yellow or orange toad, This toad has a highly unusual mode Unusually for a toad, Boulenger’s adhesive
sometimes with black markings, provides of reproduction: the eggs are fertilized Asian tree toad is a good climber, disk
a good example of warning coloration. Its and the young develop inside the with adhesive disks on all its toes. on toes
skin produces poison when it is attacked mother. After a 9-month gestation It has warts and small spines on
and predators learn to avoid it, having period, she gives birth by inflating its skin, and varies in color from
experienced the pain once, associating herself with air and pushing out 2 – 16 greenish brown to black, with
bright color with a noxious stimulus. Like tiny toadlets. The western Nimba toad yellow spots; some females also
many frogs and toads living in Central hides in rocky crevices in the dry season. have a purple tinge. It is usually
America, its numbers have declined found along rivers and streams in
drastically in recent years.
Rhinoderma darwinii snout. Adults live in damp, shady
vivid warning valleys close to flowing water, and are
coloration Darwin’s frog largely nocturnal, feeding on insects
and other small animals. During the
black Length 1 – 11⁄4 in breeding season, the male attracts PARENTAL CARE
markings (2.5 – 3 cm) the female with a soft, bell-like call.
Habit Mostly terrestrial Once the eggs have been laid, the After a female Darwin’s frog has
long limbs Breeding Year round male cares for them until they hatch. deposited a clump of up to 40 AMPHIBIANS
season large eggs on the ground, the
Location S. South America Status Vulnerable PHYSICAL FEATURES male guards them for 2 – 3 weeks.
This small frog has a characteristic fleshy When the embryos begin to move,
Brachycephalus ephippium An inhabitant of proboscis on the end of its nose. Other features he swallows up to 15 eggs and
include thin legs, long fingers, webbing on its toes, retains them in his vocal sacs,
Spix’s saddleback toad small eardrums, and eyes with horizontal pupils. where they hatch into tadpoles.
The tadpoles require only their
Length 3⁄8 – 3⁄4 in mountain forest in own egg yolk in order to develop
(1 – 2 cm) into froglets. These then emerge
Habit Mostly the southern Andes, from the father’s mouth.
terrestrial
Breeding Not recorded Darwin’s frog is famous
season
Status Least concern for brooding its eggs in fleshy
its vocal sacs—a form proboscis

Location E. South America of parental care seen thin legs
in few other amphibians.

Brown or green above with

a black underside, it is

easily recognized by

its small size and

sharply pointed

Pseudis paradoxa are adaptations for a highly aquatic It lives in ponds, lakes, and swamps,
lifestyle: it has upward-pointing eyes and and feeds on aquatic invertebrates,
Paradoxical frog nostrils that enable it to float just beneath stirring up mud with its feet to disturb
the water’s surface, fully webbed prey before catching it. The female lays
Length 2 – 23⁄4 in hind feet for swimming, eggs in a floating foam nest.
(5 – 7 cm) and slimy skin.
Habit Wholly aquatic
Also known as the gold frog, this Location N. and C. South Breeding Rainy season powerful,
species is an inhabitant of mountain America season muscular
rain forest, where it lives mainly among Status Least concern hind limbs
leaf litter, preying on insects and other
small invertebrates. During dry spells, In most frogs, adults are considerably slimy skin webbed
it hides in crevices. The Spix’s larger than mature tadpoles, but in long fingers toes help
saddleback toad is a ground dweller— this species the situation is reversed. in swimming
it cannot jump, nor can it climb well, Paradoxical frog tadpoles have an
because its stubby toes lack adhesive unusually long life, and can grow
disks. It has a saddlelike, bony plate up to 10 in (25 cm) long—about 4 times
embedded in the smooth skin of its longer than the adult frog. During the
back, and is bright orange above, with final stage of metamorphosis, the animal
a yellow underside. The female lays 5 shrinks, largely by absorbing its very long
or 6 large eggs on land; there is no tail. Most of the features of the adult frog
tadpole stage, the eggs hatching
directly into small frogs.

456 FROGS AND TOADS

Rhinella marina BIOLOGICAL CONTROL FORMIDABLE SURVIVOR
The cane toad is highly adaptable, in terms
Cane toad Introduced into Australia in 1935, of both survival and reproduction. It is able
as well as into many Pacific islands, to thrive in almost any habitat, and can even
Length 2 – 9 in the cane toad is the target of tolerate brackish water. It feeds on any animal
(5 – 23 cm) eradication programs, rather it can catch, and can survive without water for
Habit Mostly terrestrial than of conservation. Most of these long periods. Breeding, which produces large
Breeding After rain programs have met with only limited quantities of eggs, occurs throughout the year.
season success, since cane toads are highly
Location Central America, Status Least concern adaptable and resilient, with a huge
South America. Introduced reproductive potential. Biological
to Australia and elsewhere control may be the best way to limit
their spread, but as yet no effective
AMPHIBIANS The cane toad is the world’s largest method has been discovered that
toad. A heavily built creature, it has leaves other amphibians unharmed.
very tough, warty brown skin that feels
leathery to the touch. It has a massive VORACIOUS FEEDER
head, with bony ridges above the eyes, Emerging at night to feed, the cane toad will
and prominent parotid glands that eat virtually anything it can fit into its mouth,
secrete a milky poison whenever the including snakes. In urban areas, they often
toad is in danger. A hungry feeder, it gather under streetlights, eating insects
eats mainly ants, termites, and beetles, attracted by the light.
but will readily consume a wide variety
of other insects and invertebrates as
well as other frogs. The cane toad is
usually solitary, except in the breeding
season. Then males call to females,
drawing their attention with a purring
trill that sounds like a running motor.
The female, which is larger than the
male, lays her eggs in long, gelatinous
strings, draping them over plants or
debris in water. Each clutch may
consist of up to 20,000 eggs. In ideal
conditions, toadlets will reach adult
size within a year of leaving the water.
This species has been deliberately
introduced into some countries in the
hope of controlling insects devastating
sugarcane crops—but its predatory
nature has devastated native wildlife.

bony ridge distinct visor
over each eye

very large
parotid glands

olive to reddish
brown skin

brown-speckled,
white or pale
yellow underside
no webbing
on front toes
SHORT AND SQUAT
With its heavy, squat body and short limbs, the
cane toad is best suited to life on the ground.
It usually crawls along or makes short hops.

TOXIC DEFENSE

The cane toad is extremely toxic
to other animals. If threatened or
squeezed, such as when in the mouth
of a predator, it oozes venom from the
large glands on its shoulders. Smaller
glands over the body also produce
venom. Anything swallowing this poison
may die very quickly—in as little as
15 minutes in some cases.

457 AMPHIBIANS

458 FROGS AND TOADS

Litoria caerulea loose, deeply folded skin allows Pseudacris crucifer INFLATED VOCAL SAC
the frog to take in a large amount of
Australian green water—an ability that makes it unusually Spring peeper Male spring peepers gather in
treefrog tolerant of drought. The Australian green shrubs and trees next to water
treefrog is a nocturnal hunter, preying Length 3⁄4 –11⁄2 in in early spring to form choruses,
Length 2 – 4 in on insects and other invertebrates, and Location S.E. Canada, (2 – 3.5 cm) giving out high, piping whistles to
(5 – 10 cm) occasionally larger animals, such as E. USA Habit Mostly terrestrial attract females. The male’s vocal
Habit Terrestrial mice. Males are smaller than females, Breeding Spring sac amplifies his call as the air is
Breeding Spring and and give out a harsh, barklike courtship season passed back and forth between the
season summer call. After mating, the female lays Status Least concern sac and lungs over the vocal cords.
Status Least concern 2,000 – 3,000 eggs in water. These frogs
Location S. New Guinea, are of considerable interest in medicine: BODY COLORATION
N. and E. Australia their skin produces several useful The spring peeper is brown, gray, or olive-
antibacterial and antiviral compounds,
and a substance that has been used to Across much of eastern North America, green, with darker patches that
treat high blood pressure in humans. the distinctive call of this tiny but highly usually form an X-shaped
agile frog is a sign that spring is under pattern on its back.
Also known as White’s treefrog, this plump body large way. It belongs to a group of species
widespread Australasian species is well head known as chorus frogs, which are adept
known for its tame behavior, and its habit climbers, with reduced webbing, and
of living in or near buildings. adhesive disks on their toes. The spring
Its color varies from green to peeper lives in woodland
greenish blue, sometimes with temporary or
with white spots. Like most permanent ponds,
tree frogs, it has adhesive spending winter
disks on its toes. In wet and dry spells
conditions, its under logs or
rotting vegetation.

AMPHIBIANS adhesive
disks

Litoria infrafrenata Litoria australis Hyla cinerea while others, called “satellite males,” are
silent and attempt to intercept females
White-lipped treefrog Giant frog Green treefrog attracted to the calling males. This
species is also known as the “rain frog,”
Length 4 – 51⁄2 in Length 23⁄4 – 41⁄4 in Length 11⁄4 – 21⁄4 in because it calls just before and during
(10 – 14 cm) (7 – 10.5 cm) (3 – 6 cm) wet weather. It often appears at night
Habit Mostly terrestrial Habit Terrestrial/ Habit Mostly terrestrial at windows, where it feeds on insects
Breeding Spring and Burrowing Breeding Spring attracted to the light.
season summer Breeding Rainy season season
Status Least concern season Location S.E. USA Status Least concern golden eyes
Status Least concern
Location New Guinea, Location N. Australia pale stripe
N.E. Australia along sides

Plain green above, with a distinctive stripe This large frog is able to survive This bright green frog can change color
underground for very long periods by quite rapidly, from yellow when
along its lower lip, this tropical species burrowing into the soil and shedding calling out for mates, to gray
numerous layers of skin, which create when the weather is cold. In the
is the largest frog in Australia, and one a cocoon around its body. It can retain breeding season, males form
large amounts of water in its bladder, choruses around pond edges;
of the biggest tree frogs in the world. body cavity, and beneath its skin. A some call out to attract mates,
related species, the water-holding frog
Found in forests and gardens, it (L. platycephala), is used as a “living
well” by aborigines, who dig up the frog
feeds after dark on insects and other and extract drinking water by squeezing
it. The giant frog is pale gray, brown,
invertebrates. It has large adhesive or bright green in color, with a dark Hyla arborea a conspicuous dark horizontal stripe on
brown or black stripe through its eyes. its head and body. It lives in overgrown
disks on its toes, and spends most It has a broad head, short, muscular Common treefrog areas near water, and hibernates in
limbs, horny tubercles on its hind feet, winter. During the breeding season,
of its life in trees. During the breeding and a pair of skin folds on its back. males make a loud quacking sound,
During the breeding season, they are and this can quickly build up into a
season, adults descend and females active during the day and can be found noisy chorus.
beside temporary pools where males
lay up to 400 eggs in water. call to females from the water’s edge. Length 11⁄4 – 2 in adhesive
Once they have mated, each female (3 – 5 cm) disks for
very large thin, lays up to 7,000 eggs in clumps that Habit Terrestrial climbing
eyes white sink to the bottom of the pond. The Breeding Spring and
stripe tadpoles are very resilient and can season summer
survive water temperatures of up Status Least concern
to 109˚ F (43˚ C). Location Europe, W. Asia

Europe is home to just a
few species of tree frogs—
this one is the most
widespread. Usually
bright green,
although sometimes
yellow or brown, it has

FROGS AND TOADS 459

Hyla chrysoscelis Agalychnis callidryas COLORATION Phyllomedusa hypochondrialis

Cope’s gray treefrog Red-eyed treefrog Orange-legged
leaf frog
Length 11⁄4– 21⁄4 in Length 11⁄2 – 23⁄4 in
Location S. Canada, (3 – 6 cm) Location Central America (4 – 7 cm) Length 1 – 13⁄4 in
C. and E. USA Habit Mostly terrestrial Habit Terrestrial (2.5 – 4.5 cm)
Breeding Spring Breeding Summer Habit Wholly terrestrial
season season Breeding Rainy season
Status Least concern Status Least concern season
Status Least concern
Location N. to C. South
This multihued frog has a green America
body, with blue and white stripes
The jewel-like coloration and red eyes on its flanks; the insides of its legs An inhabitant of arid regions, this long,
make this one of the most striking frogs. are red and yellow. By day, it rests
In the breeding season, males on leaves, with its legs folded along slender frog secretes a waxy substance
congregate on branches overhanging a its sides in order to hide all the bright
pond, and call out to females with a parts of its body, its green back from special glands, and rubs it all over
series of clicks. The male clambers onto providing camouflage.
the female’s back to mate, and she its body to reduce water loss. Females
descends to the pond, carrying the male
with her, to take up water, then climbs surround their fertilized eggs with
back up into the
tree to lay a prominent GOOD CLIMBER fluid-filled capsules
batch of about red eyes Like all tree frogs, the red-eyed
The blotchy gray coloring of this frog 50 eggs on a treefrog has well-developed pads in order to
enables it to blend perfectly with a leaf over the
background of lichen-covered tree water. The on all its toes to aid climbing. provide extra green
trunks. It can change color in different process is water for the back
climatic or lighting conditions: turning usually repeated several
darker in cold, dark conditions, times, the female drawing developing
and paler in bright light. Its blood up water between each
contains glycerol, an “antifreeze” new batch of eggs. eggs. The
that enables it to survive subzero The eggs hatch after
temperatures. Cope’s gray treefrog about 5 days, and the orange-legged
is almost identical to another species, tadpoles fall into the pond.
H. versicolor, which has a deeper- leaf frog
voiced call and twice the number
of chromosomes. produces

an unpleasant

odor to ward

off potential orange AMPHIBIANS
predators, underside

and may also

feign death.

Scinax ruber Triprion petasatus Acris crepitans foliage near swamps, ponds, streams,
and lakes, and often basks in the sun. In
Red-snouted treefrog Yucatan shovel- Northern cricket frog early spring, large numbers converge
headed treefrog in ponds, where the males call loudly to
Length 1 –11⁄2 in Length 1⁄2– 11⁄2 in attract females, with a series of metallic
Location S. Central (2.5 – 4 cm) Length 21⁄4 – 3 in Location E. and S. USA (1.5 – 4 cm) clicks similar to the sound of crickets. In
America to N. South Habit Mostly terrestrial (5.5 – 7.5 cm) Habit Mostly terrestrial some areas, tadpoles have black tips on
America, Caribbean Breeding Rainy season Habit Mostly terrestrial Breeding Spring their tails to distract predators.
season Breeding Rainy season season
Status Least concern season Status Least concern eggs in the pouch, where they mature.
Status Least concern The developing young are joined to the
Location Mexico (Yucatan mother’s blood system by a link similar
region), N. Central America to the placenta of mammals. After
heavy rain, the mother releases young
The red-snouted treefrog has a slender darker spots on This frog is able to leap large distances tadpoles into water (in some closely
yellow, silver, or gray body. During the gray body due to its long, powerful hind limbs. Its related species, the young are released
breeding season, males call very loudly other characteristics include rough skin, as tiny adults). This frog is active at
to attract mates. The females, which and a distinctive, dark, triangular mark night, and hides under logs during
are slightly larger than the males, between the eyes. It is found among winter and dry periods.
select their mates on the basis of
size, preferring those that are about ducklike Gastrotheca monticola broad head
20 percent smaller than they are. snout
This ratio allows closest contact with Mountain marsupial
the male cloaca, so that the maximum Characterized by the unique shape frog
number of eggs can be fertilized. The of its head, the Yucatan shovel-headed
female scatters the eggs around the treefrog has a flattened, ducklike snout, Location N.W. South Length 11⁄2 – 21⁄4 in
pond to reduce the impact of predation. and saddlelike flaps behind the eyes, the America (4 – 6 cm)
function of which is unknown. It is gray, Habit Wholly terrestrial
pointed snout brown, or green, with darker spots, and Breeding Spring and
has webbed toes and well-developed season summer
flattened adhesive pads on its fingers and toes. Status Least concern
body This tree frog lives in shrubs and trees
that occur in patches in grassland. Active
only at night, by day it commonly hides in The female mountain
tree holes, which also provide a refuge marsupial frog has a brood
during cold and dry weather. pouch on her back. During
mating, the male places the

460 FROGS AND TOADS

Hyalinobatrachium valerioi Dendrobates auratus PATERNAL CARE Oophaga pumilio

La Palma glass frog Green and black Strawberry poison-
poison-dart frog dart frog
Length 3⁄4 – 11⁄2 in
Location S. Central America (2 – 3.5 cm) Length 1 – 2 1⁄4 in Length 3⁄4 – 1 in
to N.W. South America Habit Mostly terrestrial (2.5 – 6 cm) (2 – 2.5 cm)
Breeding Rainy season Habit Wholly terrestrial Habit Wholly terrestrial
season Breeding Rainy season Breeding Rainy season
Status Least concern season season
Status Least concern Status Least concern
Location S. Central America Location S. Central America
to N.W. South America
The female green and black
This small, delicate frog has translucent This brilliantly colored, tropical American poison-dart frog lays clutches of Although not the most toxic poison dart
skin that gives it the appearance of being frog belongs to a family of about 5 – 13 eggs in leaf litter, but it is frog, this Central American species is still
made from glass. It is an excellent 179 species that includes the most the male that guards the eggs, highly poisonous. Like other poison dart
climber, with large adhesive disks on its poisonous amphibians in the world. Like sometimes caring for more than frogs, it relies on its chemical defense
fingers and toes. Females attach their its relatives, it lives on the ground, and one clutch at a time. When the eggs system to keep it out of trouble. Its colors
eggs to foliage overhanging streams. uses the poison as a defense. Its bright hatch, he carries the tadpoles on his are very variable: in some places it is
When the pink or red tadpoles hatch, back, to small pools in tree holes. bright red, but in others it can be brown,
they drop into the water and burrow colors show predators that blue, or green. Females lay eggs in
into the mud or sand on the streambed. it is toxic, allowing it to hop around unmolested on the batches of 4 – 6, and deposit
forest floor. Courtship among green them singly in water-filled
and black poison-dart frogs is conducted tree holes.
in a highly unusual way; females take
the lead, enticing the males to mate
by beating their partners on the back

with their hind feet.

WARNING COLORATION short
The green and black poison-dart frog is small limbs
with a pointed head. A brightly colored species,
AMPHIBIANS it is black with green patches, and may sometimes
have a golden sheen. This coloring functions
as a warning to predators.

Ranitomeya dorisswansonae blotches on a black background. It is Rana temporaria beyond the Arctic Circle. An inhabitant
only known to occur in a forest fragment of damp places, it spends most of its
Doris Swanson’s no bigger than 0.2 square miles (0.5 European common adult life on land, returning to water only
poison-dart frog square km), where it lives on the forest frog to escape attack and to breed. In early
floor and on low-growing bromeliads. spring, large numbers of these frogs
Location N.W. South Length 2⁄3 – 7⁄10 in It belongs to a genus of small poison- Location Europe, Length 2 – 4 in make their way to shallow ponds. The
America (l.7 – 1.8 cm) dart frogs recently separated from N.W. Asia (5 – 10 cm) males call the females with a deep,
Habit Wholly terrestrial Dendrobates on the basis of genetic Habit Mostly terrestrial growl-like croak, and after mating the
Breeding Not known evidence. Like all the brightly colored Breeding Spring females lay floating clumps of several
season poison dart frogs, the toxins in their skin season thousand eggs. In warm ponds, the
Status Vulnerable are derived from Status Least concern tadpoles reach maturity in 6 weeks, but
insect prey. in cool water they can take 4 months.

black
bands on
hind legs

Found in the species-rich central The common frog is one of the most
cordillera of Colombia in 2006, this widespread amphibians in Northern
tiny frog is strikingly patterned with red Europe, with a range that extends well

Hylarana albolabris African members are generally poorly Lithobates pipiens have pale borders. Found in meadows
known, but those living south of the near ponds and marshes, it feeds on
Forest white-lipped Sahara belong to the genus Hylarana. Northern leopard insects and other invertebrates, and
frog Characterized by the white stripe on its frog spends winters and dry spells hidden
upper lip, this African species has a under rocks. The male’s call is a loud,
Length 21⁄4 – 4 in pointed snout, prominent folds of skin Length 2 – 31⁄2 in deep, rattling “snore,” interspersed with
(6 – 10 cm) down each side of its back, and large (5 – 9 cm) grunts. This frog breeds from
Habit Mostly terrestrial adhesive disks on its toes. The male has Habit Terrestrial/Aquatic March to May,
Breeding Summer a larger eardrum than the female and, Breeding Spring depending on
season in the breeding season, develops large season the latitude.
Status Least concern glands on the upper forelimbs, which Status Least concern
Location W. and C. Africa enable him to maintain a firm grip on the Location S. Canada,
female while mating. Eggs are laid in still N. USA
or slow-moving water. This frog lives on
Frogs belonging to the family Ranidae, low vegetation in secondary rain forest This frog is green or brown with a long, pale stripe
often referred to as the “true” frogs, and woodland but is also found in pointed snout, and 2 or 3 rows of powerful along
number more than 340 species, and are cultivated areas. Its tadpoles have a large, irregular, dark spots that hind legs upper jaw
found in all the world’s major continents. fringe of skin along their lower lip, the
function of which is not known.

FROGS AND TOADS 461

Lithobates catesbeianus AMPHIBIAN INVADER Lithobates sylvaticus temperatures. It often breeds while
the snow is still on the ground and the
American bullfrog Wood frog breeding ponds are partially frozen.
The wood frog varies in color from pink
Length 31⁄2 – 8 in Length 11⁄2 – 31⁄4 in through various shades of brown to
(9 – 20 cm) (3.5 – 8 cm) black, with darker markings. It has
Habit Mostly aquatic Habit Mostly terrestrial stripes on its legs and a characteristic
Breeding Spring and Breeding Spring dark patch, called the “robber’s
season summer season mask,” behind its eyes.
Status Least concern Status Least concern
Location S.E. Canada, Location Canada, E. USA
W., C., and E. USA.
Introduced to Europe, The American bullfrog has a varied
South America, and E. Asia diet, including mammals, reptiles,
and other frogs. Originally from
Renowned for its voracious appetite, eastern North America, it has been Although the wood frog is usually
the American bullfrog is the largest introduced into several regions farther found in temperate woodland in the
frog in America. It lives in lakes, ponds, west, where it has had a harmful southern part of its range, it can
and slow-flowing streams, spending effect on local freshwater wildlife. survive well into the arctic circle,
most of its life in water or close to it. farther north than any other frog in
In some parts of its range it is plain PHYSICAL APPEARANCE North America. Its blood contains
green above, while in others it is The most prominent features of this large frog chemicals that act as an “antifreeze,”
boldly patterned. During the breeding are its long, powerful hind limbs and prominent enabling it to live in subzero
season—in spring and summer—males eardrums. It is green above, with brown
defend their territories, and produce a markings, and white below. Pelophylax ridibundus eyes. An inhabitant of lakes, ponds,
deep, sonorous call from a vocal sac ditches, and streams, the marsh frog
under their throats. After mating, large Marsh frog feeds on fish, lizards, snakes, mice,
females lay several thousand eggs. eardrums and other frogs, as well as on insects
Their tadpoles can take up and other invertebrates. Females lay
to 4 years to become adult. Length 31⁄2 – 6 in up to 12,000 eggs in water.
(9 – 15 cm)
Habit Mostly aquatic black spots black bands
Breeding Spring on back on legs
season
brown Location Europe, Status Least concern AMPHIBIANS
markings W. and S.W. Asia

Europe’s largest frog, this brown
or green species has typically long,
powerful hind legs, longitudinal folds
of skin on its back, and close-set

Conraua goliath and smooth, slippery skin,
it is well adapted to a life
Goliath bullfrog underwater, and is an
excellent swimmer and
Location Cameroon, Length 4 – 16 in diver. The tips of its toes are dilated,
Equatorial Guinea (10 – 40 cm) but the function of this feature is not
Habit Mostly aquatic known. The goliath bullfrog lives along
Breeding Rainy season streams in jungles, and feeds on other
season frogs, small reptiles, and mammals.
Status Endangered It rarely emerges on land, but when it
does it is quick to dive back into water
Rana dalmatina by their thicker forelimbs. This frog whenever threatened or disturbed.
inhabits open woodland and swampy Unusually among frogs, the male of this
Agile frog meadows, spending winter and dry species is larger than the female and
periods under logs and rocks, or buried does not call to attract mates. Little
Length 2 – 31⁄2 in under vegetation, although males often Found exclusively in West Africa, this is known about the breeding habits
(5 – 9 cm) overwinter under ice in ponds and is the world’s largest frog. With its of the goliath bullfrog.
Habit Mostly terrestrial lakes. They breed as soon as the ice powerful hind limbs, long, webbed toes,
Breeding Spring begins to melt in spring, and the eggs
season are laid in clumps in water.
Status Least concern
Location N., C., and
S. Europe very long hind limbs pointed
snout

With its exceptionally
long hind legs, the agile
frog is a remarkable jumper,
capable of leaping several
yards. It is pale brown, with
brown-striped yellow flanks,
and has dark brown spots
on its back that are usually
arranged in an inverted “V”
pattern. Males can be
distinguished from females

462 FROGS AND TOADS

Cornifer guentheri Unusually for a frog, the lower jaw Cornifer vitiensis unwebbed fingers and toes. The female
of Gunther’s triangle frog contains lays a small number of large eggs on
Gunther’s triangle toothlike projections, made of bone, Fiji tree the ground, which hatch directly into
frog which it uses to hold its prey. These frog small froglets, the tadpole phase being
“tusks” are larger in males than in completed within the egg. Little is
Location Solomon Islands Length 2 – 31⁄4 in females. The female lays clumps of Location Fiji Length 11⁄2 – 2 in known about the behavior and life
(5 – 8 cm) large eggs, which hatch directly into (3.5 – 5 cm) cycle of this frog.
Habit Mostly terrestrial froglets, in damp soil. The froglets Habit Mostly terrestrial
Breeding Rainy season have folds in their skin, which help Breeding Spring and underground, it encases itself in
season the absorption of yolk from the eggs. season summer a cocoon that reduces water loss.
Status Least concern Status Near threatened It feeds on other frogs as well as
“horns” on head insects and other invertebrates.
This bullfrog is very large, with a
flat, triangular massive head and horny tubercles
head on its hind feet, for digging. During
the breeding season, the male, which
This forest-floor animal The Fiji tree frog is a slender-bodied is larger than the female, develops
strongly resembles the amphibian that is encountered only in a pair of toothlike tusks on the lower
Asian spadefoot toad the tropical forests of Fiji. It has a flat jaw, which he uses in fights over
(see p.451), although it is head with large eardrums, wrinkled territory with other males. He
not closely related. It also skin, and adhesive disks on its produces a loud, booming call to
uses the same kind of camouflage attract the female. After mating in
to avoid being seen: its projections, Pyxicephalus adspersus flooded pools, the male guards both
or “horns,” help break up the the eggs and the tadpoles. As the
outline of the frog’s head, African bullfrog tadpoles develop, the male digs
making it difficult to detect channels to enable them to swim
against a background of leaves. away to larger expanses of water.

Ptychadena oxyrhynchus top of its very pointed snout. This frog Location C. to southern Length 31⁄4 – 9 in warts and
inhabits open savanna and thornveld Africa (8 – 23 cm) ridges on skin
Sharp-nosed in areas where temporary ponds form Habit Mostly terrestrial
grass frog after heavy rain, and feeds on insects, Breeding Rainy season
especially crickets, and other season
invertebrates. During dry and cold Status Least concern
weather, it remains hidden. The male
AMPHIBIANS Location W. and C. to Length 11⁄2 – 23⁄4 in makes a high-pitched trill to attract The African bullfrog inhabits wet and
southern Africa (4 – 7 cm) the female, and mating takes place dry savanna, where it may remain
Habit Mostly terrestrial on the surface of water after heavy buried underground for very long
Breeding Spring rain. The eggs are fertilized in the air periods, even up to several years
season and ejected onto the surface of the if there is no heavy rain. When
Status Least concern water in small batches.
green
sharply or brown
pointed coloration
snout

This highly athletic frog can move brown
very fast through grass and in patches
water, its powerful hind legs
enabling it to take prodigious leaps.
It is yellowish brown above, with
brown or black spots and patches,
and has a white underside. A pale
triangular patch is present on the

Mantella viridis in tropical forest, is yellow or pale green tubercles on very wide
on its back and head, black along its hind feet mouth
Green mantella sides, and has a white stripe running
along its upper lip. Active during the
Location N. and Length 3⁄4 – 11⁄4 in day, it feeds on insects and other Mantella aurantiaca that it is toxic. Active during the day,
E. Madagascar (2 – 3 cm) invertebrates. The male calls out with it searches for small animals on the
Habit Wholly terrestrial a series of clicks to attract the female. Madagascan golden forest floor. During the breeding
Breeding Rainy season After mating, which takes place on land mantella season, adults mate on land, and
season during the rainy season, the female lays females lay their eggs in moist leaf
Status Endangered eggs close to streams. litter. Once the tadpoles have hatched,
they are swept into pools by rain. Like
white stripe Length 3⁄4 – 11⁄4 in other mantellas, this species is
along upper lip (2 – 3 cm) threatened by deforestation.
Habit Wholly terrestrial
black sides Breeding Rainy season
season
The mantellas are 16 species of Status Critically black eyes orange body
brightly colored frogs, exclusive endangered
to Madagascar, which Location W. central
are all threatened with Madagascar
extinction due mainly to
the destruction of their adhesive Strikingly similar to poison-dart frogs
forest habitat. Their numbers disks on (see p.460), which live in the American
are further depleted by the toes tropics, this Madagascan frog has
worldwide pet trade. The green evolved bright colors to warn predators
mantella, which lives near streams

FROGS AND TOADS 463

Hemisus marmoratus Hyperolius marmoratus Afrixalus fornasinii leaf, fastening it with a glue that she
secretes. When the eggs hatch, the
Mottled shovel-nosed Painted reed frog Greater leaf-folding tadpoles drop into the water below—
frog frog a system that gives them a head start
Length 1 – 11⁄2 in in the struggle to avoid being eaten.
Length 11⁄4 – 11⁄2 in Location E. to S.E. Africa (2.5 – 3.5 cm) Length 11⁄4 – 11⁄2 in Greater leaf-folding frogs are brown
(3 – 4 cm) Habit Terrestrial (3 – 4 cm) with dark, longitudinal stripes, and
Habit Terrestrial Breeding Spring and Habit Wholly terrestrial have slender limbs with adhesive
Breeding Rainy season season summer Breeding Spring and disks as well as webbing on their
season Status Least concern season summer fingers and toes. They live in dense
Status Least concern Status Least concern vegetation around pools and swamps,
Location W. and C. to Location S.E. Africa and are active at night. At the onset
S.E. Africa of the breeding season, large males
call from an elevated position in
Unusually for a burrowing frog, this squat The painted reed frog is a small, Many tree frogs lay their eggs vegetation, making rapid clicks to
species digs into soil head first, using its graceful animal with highly variable above the ground, but this species attract mates. However, smaller males
sharp, tough, spadelike snout, rather coloration—it may be striped, spotted, has a particularly skillful technique. often stay silent, waiting by the callers.
than digging backward with its hind feet. or plain brown. A good climber, its The female lays her clutch on a leaf When females approach, the
It preys on ants and termites. Females fingers and toes are equipped with overhanging water, and then folds the noncalling males sometimes manage
lay up to 2,000 eggs in underground adhesive disks as well as webbing. to intercept them and mate.
chambers close to pools. They guard the It inhabits areas close to permanent long limbs
eggs until they hatch, then dig a tunnel to ponds, lakes, and swamps; like most pale stripes along back
release the tadpoles into the water. frogs, it spends dry spells hidden
under logs and rocks. Active at
plump night, it feeds on insects and other
body invertebrates. During its long breeding
season, which extends through spring
and summer, males form choruses AMPHIBIANS
close to ponds, and call very loudly
to attract mates. Females may come
to the chorus more than once in a
season, laying a clutch of eggs in
small clumps in water at each visit.
Males vary in the number of nights
they spend in a chorus; those that
call on the greatest number of
nights get the most matings.

Kassina senegalensis beige or yellow to gray, with bold, dark Rhacophorus nigropalmatus grasp her during mating. Active at night,
brown or black stripes and blotches. Wallace’s flying frog is found mostly in
Bubbling kassina An inhabitant of low-lying savanna Wallace’s flying frog brush and forest, and is also frequently
and sand dunes, it lives close to ponds found close to human habitation. During
Location W. and C. to Length 11⁄4 – 2 in and pools. In the breeding season, Location S.E. Asia Length 23⁄4 – 4 in the breeding season, the female lays up
S.E. Africa (3 – 5 cm) males begin calling in late afternoon (7 – 10 cm) to 800 eggs in a foam nest attached to
Habit Mostly terrestrial away from water. By nightfall, they Habit Terrestrial foliage overhanging water. When the
Breeding Rainy season have moved closer to call from the Breeding Rainy season eggs hatch, the tadpoles emerge and
season pond edge. Mating occurs in water, season fall into the water below.
Status Least concern and the eggs are attached individually Status Least concern
to aquatic plants, often in clusters. prominent eyes with
horizontal pupils
Adapted for walking rather than There are over 80 species of
hopping, the bubbling kassina has Rhacophorus frogs, several flat
slender limbs and slight webbing on of which—including Wallace’s head
the toes of its hind feet. Its plump, flying frog—use their
elongated body varies in color from feet to glide from
tree to tree. The
Leptopelis modestus shaped patch on its back. Males call partial webbing
to females from trees, producing a deep between their
African treefrog “clacking” sound while displaying their toes acts as
bright blue or green throat. They will a parachute,
Location W. Africa, Length 1 – 13⁄4 in fight to defend their calling positions. enabling them
central E. Africa (2.5 – 4.5 cm) to “fly” across
Habit Terrestrial forward-pointing wide gaps to escape predators,
Breeding Spring and eyes steering themselves in midair.
season summer Wallace’s flying frog is bright
Status Least concern long limbs green with white spots, and
has a flat head with large,
Also called the modest treefrog, protruding eyes and
this species has a broad head visible eardrums,
with a wide mouth, large eyes, and and large adhesive
conspicuous eardrums. Gray or pale disks on its fingers
brown, it has a darker hourglass- and toes for climbing.
The male is smaller
than the female,
and has pads on
his thumbs so
that he can

AMPHIBIANS464

WALLACE’S FLYING FROG
The large webbed feet of Wallace’s flying frog act like
parachutes as it leaps from tree to tree. This slows its
descent so that the frog spends more time in the air and
can travel greater distances.

FROGS AND TOADS 465

Chiromantis xerampelina survive in savanna that has a long dry BUILDING A COMMUNAL FOAM NEST
season. Its skin is adapted to reduce
Gray foam-nest frog water loss, and it excretes dry droppings During the breeding season, the she produces a secretion that one
rather than watery waste. Usually gray male gray foam-nest frog—which can or several males whip into a foam with
Location Southern Africa Length 2 – 31⁄2 in or pale brown, this frog can change be distinguished from the female by their legs. The female then ejects her
(5 – 9 cm) color for camouflage—at night it is the pads he develops on the first eggs—up to 1,200 at a time—into
Habit Mostly arboreal usually dark-colored, but it can and second toes of his forelimbs— the foam, and one or more of the males
Breeding Rainy season become almost white at midday. calls out to females from branches shed sperm onto them. The exterior of
season overhanging a pool. He may be joined the nest hardens to protect the eggs,
Status Least concern LIVING IN TREES in this by one or more other males. but the inside remains moist. After the
The gray foam-nest frog has a compact body and When a female arrives, one of the eggs hatch, the tadpoles burrow out
prominent eyes with horizontal pupils. It possesses males clasps her, they mate, and of the nest and fall into the water below.
the typical adaptations for an arboreal lifestyle:
This tree frog and its close relatives are long, slender limbs, and adhesive disks on all its
remarkable for their breeding method toes. Its fingers and toes are also webbed.
and their ability to

adhesive
disks

Breviceps adspersus and lodges itself firmly in its burrow. Phrynomantis bifasciatus Gastrophryne olivacea AMPHIBIANS
The females are much larger than the
Bushveld rain frog males. Since the male is too small to Banded rubber frog Great Plains narrow-
clasp the female during mating, the mouthed toad
Length 11⁄4– 21⁄4 in female emits a secretion from her Length 11⁄2 – 21⁄4 in
(3 – 6 cm) back that acts as a glue, keeping (4 – 6 cm) Length 3⁄4 – 11⁄2 in
Habit Terrestrial the mating pair together. Habit Mostly terrestrial (2 – 4 cm)
Breeding Rainy season Breeding Rainy season Habit Mostly terrestrial
season globular body season Breeding Spring and
Status Least concern Status Least concern season summer
Location Southern Africa Location Southern Africa Status Least concern

Location C. and S. USA,
N. Mexico

The bushveld rain frog lives

mostly underground, emerging

to feed and mate only after rain.

It has a stout body—either light Also known as the Western narrow-
mouthed toad, this species has a
or dark brown, with rows of narrow, pointed head with small eyes,
a stout body, and short legs that allow
lighter, yellowish or orange flattened it to burrow and hide in small crevices.
patches with dark borders— face Brown or gray in color, it is sometimes
distinguished by the dark, leaf-shaped
and short, stout limbs typical of pattern on the surface of its back. In
spring, after heavy rain, Great Plains
most burrowing species. When narrow-mouthed toads are known
to gather in large numbers around
cornered, this frog inflates its body temporary pools. The males call out
to the females, making a protracted
Paedophryne amauensis brown or gray with a blue–white Unusually for a frog, the short-legged buzzing sound. After mating, the
speckled pattern. It has a broad banded rubber frog walks and runs females lay their eggs in the pool.
Paedophryne head and relatively long legs, and is rather than hops or jumps. It is black The tadpoles develop rapidly, before
amauensis capable of jumping 30 times its own and glossy, with mainly pink or red the water dries up.
body length. Discovered in 2009, spots and stripes down its back; these
Length 1⁄4– 3⁄16 in (7–8 mm) P. amauensis is considered by some change color throughout the day, turning
Habit Terrestrial scientists to be the smallest vertebrate paler in bright light. Its head is pointed,
Breeding Not recorded species in the world. and it has small eyes with round pupils.
season This frog feeds on insects, mainly
Status Not evaluated termites and ants. If threatened, it
Location Papua New Guinea raises itself on outstretched limbs
and inflates its body. It also
Paedophryne amauensis is a produces a highly toxic substance
tiny frog, found in only one from its skin, which may be lethal to
locality in Papua New Guinea. Its humans if ingested. Males produce
upper sides are dark brown with a trilling courtship call from the pond
irregular patches, and the belly is edge, and females lay clumps of up
to 600 eggs, which they attach to
aquatic plants.



FISHES

468 FISHES

fishes

PHYLUM Chordata Fishes were the first backboned animals UNDERWATER LIFE
CLASSES Cephalaspidomorphi, to appear on Earth, and they form the
largest group of vertebrates. Unlike the Most fishes (such as these butterfly
Chondrichythyes, fishes) spend their entire life in
Osteichthyes water, although a small
number of species can
ORDERS 83 other major divisions of vertebrates, survive short periods
FAMILIES About 540 however, fishes are not a natural out of water.
SPECIES About 33,000 group; instead, they are an

informal collection of 8 classes that are only distantly

related to one another. A typical fish breathes using

gills, has a body covered with scales, maneuvers

using fins, and is ectothermic (cold-blooded). Most

species live in either freshwater or the sea, but a

few species move between both environments.

FISHES Evolution of jaws was the appearance of teeth. fins, and a symmetrical tail. Also skeleton, although this takes different
Having jaws and teeth made it important were the evolution of more forms in each of the 3 main groups of
Living fishes are usually divided into possible for acanthodians to feed on a mobile jaws and gill chambers that fishes. In jawless fishes, the body is
3 major groups: jawless, cartilaginous, wide range of food. They also had could be more easily ventilated. supported by a simple rod called the
and ray-finned. Each of these groups several pairs of spines along the lower notochord and some have rudimentary
had a different ancestor and evolved sides of their body, from which the Anatomy vertebrae. Sharks, skates, and rays
separately from the others. paired fins of fishes evolved. Unlike
the early jawless fishes, their body Fishes have several physical FIN TYPES
The first fishes appeared more was covered with scales. adaptations for life in water. The A fish’s dorsal, anal, and tail fins occur singly
than 500 million years ago, having body of a fish is covered with smooth along the midline of the body, while the pectoral
probably evolved from soft-bodied, Fishes with a cartilage skeleton first scales, and has fins to provide power, and pelvic fins are paired. The common carp
filter-feeding invertebrates. Like living appeared about 370 million years ago. steering, and stability. All fishes have (shown here) has only one dorsal fin; however,
jawless fishes, these fishes had a These were the ancestors of living gills for extracting oxygen from some other fish have 2 or 3 dorsal fins.
round, fleshy mouth without jaws, sharks, skates, and rays. water, and all have an internal
but unlike them, many lacked teeth. dorsal fin
Some 50 million years before the gill cover
The first fishes (indeed, the first appearance of cartilaginous fishes, a fin rays
animals) with movable jaws arose group of fishes with a bony internal
around 440 million years ago. Known skeleton had appeared. There are tail
as acanthodians (or spiny sharks), 2 main groups of fishes: fleshy-finned (caudal)
their jaws evolved from their front gill fishes, which have fins supported by fin
arches. Linked to the development bony skeletons fringed with rays; and
ray-finned fishes, in which the fins are
CEPHALASPIS supported only by fin rays. The
fleshy-finned fishes almost certainly
gave rise to the first 4-limbed land left pectoral fin anal
vertebrates. The ray-finned fishes (ventral) fin
appeared at about the same time left pelvic fin
but have since become a far larger
and more successful group. They
gradually developed features that
made them more efficient swimmers,
including thinner scales, highly flexible

SCALES PLACOID GANOID CYCLOID

STICHOCENTRUS Fishes have several types of scales, made CTENOID SCALE PATTERNS
of various materials. Cartilaginous fishes
FISH FOSSILS have toothlike placoid scales (dermal Placoid scales are embedded in the skin, with the widest
Among the first fishes to appear was a form denticles). Some primitive bony fishes have part facing outward, and give the skin a rough texture. Ganoid
called Cephalaspis (top). It had a jawless mouth, thick, relatively inflexible scales. They include
and its head and gills were protected by a large, diamond-shaped ganoid scales, found in scales interlock and are joined to one another by fibres.
bony shield. By contrast, a fossil of the bony fish sturgeons, and layered cosmoid scales, seen Cycloid and ctenoid scales are arranged so that the
Stichocentrus (above) reveals jaws, scales, and a in coelacanths. Like placoid scales, these are exposed surfaces overlap with one another, forming a
much lighter and more flexible internal skeleton. made of dentine and a substance similar to smooth, flexible covering.
enamel. Bony fishes have thin scales made
of bone, with one end embedded in the skin
and the other exposed: cycloid scales have
a smooth exposed surface, while ctenoid
scales are rough or spiny.

FISHES 469

GILLS gill arch gill esophagus However, some deep-sea fishes have
gill raker filaments large eyes so that they can collect as
A fish’s gills are located in internal much light as possible.
chambers on either side of the body, mouth
just behind the mouth. In most Water is an effective medium for
species, each gill consists direction transmitting sound, and most fishes TUBULAR EYES
of a framework of bone or cartilage, of water are able to respond to sound waves.
supporting tissues that contain movement Sound vibrations are usually LARGE EYES
densely packed capillaries. As water oral transmitted through the bones and EYES
enters the gill chambers, valve gill flap tissues of the head to the inner ear,
it is first sieved clean by structures although in some species they may Fishes that live in habitats with little light often
called gill rakers. Behind the rakers GAS EXCHANGE be amplified by the swim bladder. have unusual eyes. Spookfishes (top) are deep-
are supports called gill arches, water fishes with tubular eyes that point upward.
which provide attachment points Water enters a fish’s gill chamber through the In aquatic animals, the distinction The pinecone soldierfish (above) lives in shallow
for gill filaments. To increase the mouth (or in some, the spiracles) and leaves between taste and smell is blurred water but avoids direct sunlight. It feeds at night,
efficiency of respiration, the through the gill openings. As it passes through because the same sense organs using its large eyes to search for food.
filaments have folds on their the gills, dissolved oxygen is transferred across often respond to chemicals that are
surface, known as lamellae. Gases the thin outer membrane of the capillaries and dissolved in water and contained in called the ampullae of Lorenzini.
are exchanged across the surface of enters the bloodstream. At the same time, food. Fishes smell using sensory These specialized nerve cells, located
the lamellae, before being carbon dioxide is expelled from the capillaries. pits (called nares), which are lined in small pores at the surface of the
distributed to the rest of the fish’s with tissues that contain olfactory skin, contain a conductive gel and
body. In some fishes, the area of the receptor cells. Most fishes have a can detect the weak electrical
lamellae is 10 times greater than good sense of smell, and some can currents produced by other animals.
that of the body’s outer surface. detect chemicals in minute Some ray-finned fish can also detect
concentration. Taste receptors are electrical signals. Certain species
eyes can be rolled back in ray-finned fishes they also have other usually found in or near the mouth, have organs that produce electrical FISHES
sockets to keep them moist uses: colors and patterns on their although some fishes have them on fields, which they use to detect
surface can be used as signals their fins, skin, or whiskerlike barbels, objects or other fish in low visibility,
muscular to warn predators, attract mates, allowing them to taste food on or and to communicate.
fin defend territories, or lure prey; near the bottom.

BREATHING OUT OF WATER the fins of some fishes have spines, Almost all fishes have what is called
By keeping their gill chambers moist, mud- which are sometimes poisonous, to a lateral-line system, which they use
skippers can survive out of water for long protect them from predators. to detect vibrations (including those
periods. They live in coastal swamps, and made by their predators and prey)
at low tide can be found using their well- All fishes have gills, which they use and changes in water pressure and
developed pectoral fins to move around to take oxygen into their bloodstream currents. These changes are detected
on exposed mudflats. (see panel, above). Some fishes by organs known as neuromasts,
which are usually housed in canals, in
have a skeleton of cartilage hardened also have other ways of taking in the bones of the head and in a lateral
by calcium carbonate, as well as a oxygen. Lungfishes, for example, line canal that runs along the side of
fully developed vertebral column. breathe air using primitive, the body beneath the scales and is
Most fishes have a skeleton made lunglike organs. Other fishes connected to the exterior via pores
of bone. In addition to a bony skull, can absorb oxygen and release that run through the scales.
vertebral column, and skeleton, they carbon dioxide through their skin.
have bony supports in the fins. Many fishes are also able to detect
Senses electrical waves and impulses. In
Although some fishes have smooth cartilaginous fishes, such as sharks,
skin, most are protected by scales, Fishes collect information about signals are received by structures
plates of bone, or spines. Scales, their environment using sensory
which are the most common systems commonly found in other
covering, provide protection and types of animals—these include
promote the efficient movement vision, hearing, touch, taste, and
of water over the body, while still smell. However, fishes also have
allowing the fish to move freely (see some unique sense organs.
panel, opposite). Glands in the skin
secrete mucus, which protects the Although most fishes have
fish from bacteria and, in some eyes, their ability to perceive light,
species, helps to reduce drag. color, shape, and distance varies
greatly between species. This
Almost all fishes have fins. There are variation can often be related
2 main types: median (or unpaired) to habitat. Fishes that live in
and paired fins. Median fins are found clear water tend to have
singly, on the dorsal or ventral midline good vision, while many
of the body. They include the dorsal, fishes that live in dark
anal, and tail (caudal) fins. The paired conditions (such as
fins—the pelvic and pectoral fins—are muddy water, caves,
arranged in twos, one on each side or the deep sea) either
of the body. Fins are used mainly for have poor vision or have
locomotion (see p.470) but in lost their eyes altogether.

TASTE
Catfishes are named after the
whiskerlike barbels found
in many species. These are
covered by taste buds and
are used to find food. This is
especially useful for species
such as the squeaker (shown
here), which lives in dark waters
at the bottom of deep lakes.

470 FISHES

RAY SWIMMING move up and down in the water quantities of seawater and excreting
column, most fishes can adjust their most of the salt. Some have chloride
Most fishes propel themselves with cells in their gills and on the inside the
sideways movements of their body buoyancy using a gas-filled gill cover (operculum) that remove
and tail. However, skates and rays organ known as the swim salts from the water that is absorbed
(including the thornback skate, shown bladder (see p.487). To and then excrete it. Freshwater fishes
here) use vertical movements of their make themselves more or control involuntary water intake from
large pectoral fins to generate the rivers and lakes in which they live
forward movement. less buoyant, gas is added to by drinking little and producing copious
or extracted from this bladder. dilute urine. They obtain the salt they
Cartilaginous fishes do not have a need from their food and have cells in
swim bladder but their large, oil-rich their gills that control its loss.
liver is less dense than water and thus
increases their buoyancy.

FISHES Swimming and slender, cylindrical body, such as eels, Marine and Temperature control
buoyancy can wriggle with ease into crevices to freshwater fishes
find food or escape from predators. Fishes are ectothermic (cold-blooded)
A fish propels itself through water Bottom-dwelling fishes typically have Fishes need mechanisms to keep the animals, which means that their
using the action of its muscles. Along a body that is compressed from top concentration of water and salts in their internal temperature is the same
either side of the backbone are to bottom, helping them remain body in a stable state. However, this as that of the surrounding water.
bundles of muscle fibers (known as inconspicuous on the seafloor. concentration is different from the Some species modify their behavior,
myotomes). By contracting these water in which they live, so they have to basking in the sun, seek shade,
muscle bundles in sequence, one a Many fishes are neutrally buoyant. counteract osmosis—the tendency of or rise and fall between warmer
fraction of a second after the other, That is, their density is similar to that liquids of different concentrations and colder depths. Others do
the fish creates a wave motion that of the surrounding water, so they can (in their cells and in their environment) this by altering their color, using
travels along its body from front to remain suspended at a constant to equate by passing through a pigments that change between
back and ultimately causes the tail to depth in the water column. Most other semipermeable membrane (the cell dark, heat-absorbing colors and
move from side to side. It is this wave fishes are slightly negatively buoyant— walls). Water always flows from a light, heat-reflecting shades.
motion that propels the fish through their fins give them lift as they move, weaker solution to a more concentrated
the water. The wave usually begins but they will sink if motionless. For one to dilute it. Therefore marine fish A few fishes—including tuna and the
near the rear third or half of the body bottom-dwelling fishes, such as tend to dehydrate and lose water great white shark and its relatives—
so that only the back end moves from skates and rays, being negatively because the salt concentration in have some similarities with warm-
side to side. In some fishes (usually buoyant is an advantage. As they their cells is lower than that of the blooded animals. Some of the heat
fast-moving ones), only the very end of surrounding seawater, and they generated by their large swimming
the tail moves. The movement is more forward must drink seawater (their bodies muscles is conserved, so that their
pronounced in fishes that have a long, movement are adaptated to do this). In contrast, internal temperature is higher than
slender body. Some fishes, including fish that live in fresh water have a that of the water around them. This
eels, can reverse the movement sideways thrust tendency to take in water and must makes it possible for these fishes to
direction of the wave of tail resultant thrust produce copious amounts of urine to remain active in cold water.
movement and so backward thrust compensate. Fish that move between
swim backward. salt and fresh water (such as salmon SURVIVING COLD
PROPULSION and eels) are physiologically able to Seawater freezes at a lower temperature than
Fins play an adapt as long as they take it slowly. In fish blood. However, the blood of some fishes,
important part in As a fish’s tail moves, it exerts a sideways fishes, water is involuntarily lost and such as this icefish, remains liquid even in
propulsion and thrust and a backward thrust on the water. The gained through the mouth and gills. extremely cold water because it contains
movement. In most fishes, resultant force acts at an angle halfway between To prevent any excesses that could be proteins that act like antifreeze.
the dorsal and anal fins act these 2. Movement of the tail from side to detrimental to their internal chemistry,
in a similar way to the side means that the resultant thrusts to left and fishes “osmoregulate” in different ways.
keel of a boat, right produce a net backward thrust. Because
stabilizing the fish’s every force in nature produces an equal and In marine fishes, the concentration
body. The paired fins have various opposite reaction, this backward thrust of salts is lower inside their bodies
uses including propulsion. Most propels the fish forward. than in the water. Sharks, rays, and
fishes use them as control surfaces, coelacanths prevent dehydration by
adjusting the angle of the fins to move retaining urea, which significantly
up and down in the water. In sharks increases their cell fluid concentration.
and some ray-finned fishes, the paired Other marine fishes counteract water
fins also provide lift as the fish moves loss by drinking large
forward, while some fishes use their
paired fins to “walk” on the bottom SURVIVING IN FRESH AND SALT WATER
and, on rare occasions, on land. The
tail fin is used mainly for propulsion The European eel can survive in both
but it also has a role in steering. fresh and salt water. It spends most
of its adult life in rivers but returns
In general, fishes move relatively to sea to breed. The opposite
slowly, rarely exceeding 3 mph (5 kph). is true of many salmon
However, some fishes are capable of and trout, which move
moving at much greater speed—for from the sea to fresh
example, the wahoo (a close relative water to breed.
of tunas) can reach 50 mph (75 kph)
for short periods.

A fish’s body shape usually reflects
the way it swims. Fishes that need to
swim at high speeds in open water for
long periods typically have a torpedo-
shaped (fusiform) body. A body that is
tall and flattened from side to side is
less efficient but is common among
reef fishes, which need to make
sudden turns around dense vegetation
or rocky surfaces. Fishes with a

FISHES 471

LAYING EGGS by external fertilization, their young
are more developed at birth and have
The perch, like many fishes, releases large a greater chance of survival. This
numbers of eggs to ensure that at least some means that live-bearing fishes can
will eventually produce adult fishes. This is produce and fertilize fewer eggs and
known as broadcast spawning. yet maintain a stable population.

Reproduction eggs, and in some species they guard Compared with other groups of LARVA FISHES
the eggs (see panel, right). In almost vertebrates, fishes include a relatively
The reproductive behavior of fishes all cases, the eggs hatch to release large number of hermaphrodites, all ADULT
is varied. Although in most cases larvae, which are incompletely formed of which are bony fishes (see p.487). METAMORPHOSIS
fertilization takes place outside the and gradually develop their skeleton, Some including certain species
female’s body and the young emerge fins, and some of their organ systems. of carp and loach, reproduce When a fish emerges from its egg, its yolk
from the eggs as larvae, there are parthenogenetically, the eggs being sac is still attached to its body and provides
many (including all cartilaginous External fertilization is a viable way fertilized without a male. Other nourishment during the first weeks of its life.
fishes) in which fertilization is internal, for fishes (and other aquatic animals) species reproduce by a process The larva of a brown trout (top) takes 3 – 4
and in some of these, the females to reproduce, partly because the called gynogenesis. These include the years to mature to the adult form (above).
give birth to live young. greater density of water makes it Amazon molly, which is a hybrid of 2
a much more suitable medium than other species and has a population that behavior. However, some fishes
In most fishes (as in many other air for transferring eggs and sperm. consists only of females. Reproduction conduct complex courtship rituals
aquatic animals), fertilization occurs Water also provides the developing occurs when a female is fertilized by a to increase their chances of attracting
externally. The male releases sperm eggs with nutrients and dissolved male of either of the 2 parent species. a suitable mate. As a prelude to
(milt) over the eggs (roe) as they are oxygen. However, the chances of an breeding, the male may change
released from the female’s body. embryo surviving to reach adulthood Some fishes breed regularly, color. For example, the male
Milt has a thick consistency, which are relatively low, particularly for often once a year. Others, however, dragonet develops more intense
prevents the sperm cells from marine fishes. To compensate for this, reproduce only once in their lifetime, colors, which are displayed to
dispersing too quickly. The eggs of females often produce large numbers and may die shortly afterward. The potential mates during elaborate
most marine fishes are made buoyant of eggs (as many as 5 million in timing of reproduction is controlled circling movements.
by droplets of oil and float freely as some species). by external factors (including changes
part of the plankton. The eggs of in temperature, light levels, or day
freshwater fishes are typically heavier In all cartilaginous fish, reproduction length) or by internal cycles (such as
and have a sticky surface so that they begins with internal fertilization. In changes in hormone levels).
adhere to objects in the water. Some sharks, for example, the inner edges
freshwater fishes make a nest for their of the pelvic fins are modified into Some fishes have preferred spawning
copulatory organs, called claspers, of grounds, laying eggs or releasing their
eye of which one is inserted into the female’s young in places where they are most
embryo likely to survive. In order to reach these
cloaca. Sea water flushes the areas, they may have to undertake
EGGS male’s sperm along a migrations of thousands of miles.
Inside its egg, an embryonic fish is nourished groove in this organ and
by fluids contained in a yolk sac. The egg case into the female’s body. In some species, large numbers
is transparent (allowing the eyes of these salmon Where fertilization is of males and females gather in shoals
embryos to be seen from the outside). The time internal, the young to breed, without any kind of courtship
taken for the eggs to hatch often depends on may be alive when
the water temperature. they are released PARENTAL CARE
from the female’s
body. In some Having released their eggs and sperm into water, many fishes have no further
species that give birth to
live young, the eggs simply contact with their developing young. However, other species actively care for

hatch inside the mother’s their eggs or young. Besides protecting their eggs by placing them in a nest,
body. In others, including
some species of sharks and rays, adult fishes may care for them by chasing away predators, cleaning them to
there is a connection between
the developing embryo and the prevent infection, or fanning them to provide oxygenated water. When the
female, along which nutrients are
passed to the embryo. eggs hatch, the parents may use various ways to protect the vulnerable
Live-bearing females invest a
relatively large amount of energy young (see below). A small number of species
in carrying and nourishing their
developing young. However, also feed their young,
compared with fishes that reproduce
including the discus fish,

which secretes a nutritious

fluid through its skin. adult male

SEAHORSES juvenile

Male seahorses (right) play
an unusual role in caring for
their young. The female
places her eggs in a pouch in
the front of the male’s abdomen, where
they are fertilized. The young are released
when they hatch, 2–6 weeks later.

MOUTH BROODING

Several hundred species of
cichlids brood their eggs in
cavities in their mouth and
throat. When the eggs hatch,
the parents also defend the
young from predators by
allowing them to shelter
inside their mouth.

472 JAWLESS FISHES

Jawless fishes PARASITISM

PHYLUM Chordata The earliest fish appear in the fossil record about 530 Adult marine lampreys use their suckerlike
CLASSES Cephalaspidomorphi million years ago. They were all jawless and had a very mouthparts to attach themselves to other fish. Once
ORDERS 2 different appearance to the fishes we know today. Four firmly attached, they rasp off flesh and blood, at times
FAMILIES 4 hundred million years ago, jawless fishes were abundant enough to kill their host. Most freshwater species are
and diverse, but today there are only two small living nonparasitic and eat small invertebrates.

SPECIES About 121 groups: hagfish and lampreys. These are

superficially similar, with an elongated body,

smooth, slimy skin, and of course, no proper jaws, but the exact

relationship to each other is still under debate. Hagfishes are

found only in the ocean, in deep temperate and cold waters.

Lampreys are found both in cool coastal water and in fresh

water, mostly in the northern hemisphere.

Anatomy while lampreys have 7. While the adult form and migrate out to
lampreys have moderately good sea. In contrast, hagfish have no
Jawless fish do not have biting vision, and use it to home in on larval stage and the young hatch
jaws, something that every other their victims, hagfish have only from eggs laid on the sea bed.
vertebrate animal does. Instead, vestigial eyes but an excellent
FISHES lampreys have a round, suckerlike sense of smell for detecting dorsal fin spinal cord
mouth armed with concentric rows carrion and small invertebrates.
of rasping teeth made of keratin, BODY SECTION notochord gill opening round,
while hagfish have a slitlike mouth Reproduction fleshy mouth
with teeth on their tongue. The The bodies of lampreys are
simple skeleton of a jawless fish is Most lampreys live and breed in fresh supported by a notochord that
made entirely of flexible cartilage, water but marine species only enter lies below the spinal cord.
including a soft cranium instead fresh water when it is time to spawn. They also have rudimentary
of a hard skull, and a simple They swim up rivers to clean gravelly vertebrae made of cartilage.
tubelike notochord instead of areas, where spawning pairs excavate
articulating vertebrae. Lampreys shallow nests, lay their eggs and then
may have a few rudimentary die. The eggs hatch into ammocoetes
vertebrae but hagfish do not and larvae that drift downriver to muddy
so cannot be called vertebrates at areas where they excavate and live
all. This has led to hagfish being in burrows. They feed by filtering
grouped with invertebrates in the microscopic organisms from the
past. The gills of hagfish open water and by sucking in detritus. After
through 1 to 16 circular pores, 6-8 years they gradually change into

Myxine glutinosa Despite having a simple cartilaginous Petromyzon marinus SUCKERS
skull, hagfish lack an intact vertebral
Hagfish column. They have been classified Sea lamprey Sea lampreys have oral discs called
with the lampreys (see p.472) as “suckers” in place of their mouths.
Location North Atlantic, Length Up to 16 in “jawless fish,” but are now considered Location North Atlantic, Length Up to 4 ft The sucker, which is wider than the
Mediterranean (40 cm) not to be closely related. The bodies Mediterranean, North (1.2 m) fishes’s body, has a fringed edge and
Weight Up to 27 oz of hagfish ooze defensive slime, America, Europe Weight Up to 51⁄2 lb contains many small teeth arranged
(750 g) especially when captured. They can (2.5 kg) in concentric rows, with larger teeth
Sex Male/Female knot their body to free the slime and Sex Male/Female surrounding the mouth opening.
Status Least concern to assist feeding. A knot formed near Status Least concern
the tail works its way up to the head, EEL-LIKE BODY
forcing the mouth away with a lump The adult sea lamprey is a parasite Both the adult and the larvae of the sea lamprey
of its preys flesh. that attacks a wide range of saltwater have eel-like bodies, which are rounded near
fish, including salmon, trout, herring, the head but flattened at the tail.
fin near tail mackerel, and some sharks. Clinging
to prey by its sucker teeth, it rasps
ATLANTIC HAGFISH flesh and gains blood using its rough-
This species of hagfish lives surfaced tongue. It migrates from the
in the North Atlantic and sea to breed in freshwater, but is
Mediterranean where landlocked in the North American
it buries itself in mud Great Lakes. The opening of
and feeds on dead the Welland Ship Canal in
and dying fish. 1929 allowed lampreys
throughout the Great
eellike body Lakes, and they had a
devastating effect on
populations of lake trout and
other fishes. Since then, the sea lamprey
population has been controlled.

CARTILAGINOUS FISHES 473

Cartilaginous fishes

PHYLUM Chordata Although often described as primitive, Feeding
CLASS Chondrichthyes cartilaginous fishes include some of the
largest and most successful of all marine All cartilaginous fishes are
ORDERS 14 predators. They are divided into 3 groups: carnivorous; however, plankton
FAMILIES 54 feeders also take in microscopic
plants. The greater part of the diet of
SPECIES ABOUT 1,200 sharks; skates and rays; and a group of most species consists of live prey,
including other fishes, invertebrates,
deep-sea fishes called chimeras. All and occasionally marine mammals.
Most species also feed on the remains
possess a skeleton made of cartilage (rather than bone), of dead animals, although only a few
species rely solely on carrion. Several
specialized teeth that are replaced throughout their lifetime, of the largest sharks and rays are filter
feeders. The teeth of these species
and skin covered with small, dense, toothlike scales. Most have been reduced in size, and stiff
projections in the gill arches have
cartilaginous fishes are marine, but some sharks, skates, developed into sievelike organs for FILTER FEEDING
straining small animals out of water.
and rays enter freshwater, and certain tropical species live Whale sharks drift slowly through water,
catching plankton, small fishes, and squid.
exclusively in freshwater. They live in warm tropical waters.

Anatomy FISHES

All the fishes in this group have an internal skeleton made of tough,
flexible cartilage. This may be strengthened by mineral deposits,
and some species have hard, bonelike dorsal spines. However, the
skeleton of a cartilaginous fish is much more flexible than that of a
bony fish (see p.486), which has a much higher mineral content.
On land, a cartilage skeleton would not be rigid enough to support
the weight of a large animal, but in water—which has a much higher
density than air—cartilage provides an effective skeleton for animals
that are up to 33 ft (10 m) long. Most cartilaginous fishes have skin
covered by thousands of interlocking scales, called placoid scales
or dermal denticles (see p.468). These have a similar composition
to teeth and give the skin a sandpaper-like texture. Some rays have

additional large, thornlike scales, while chimeras
lack scales of any sort. Unlike bony fishes,
cartilaginous fishes do not have a gas-filled
swim bladder.

serrated flat, TEETH
edge interlocking
teeth Cartilaginous
jawbone fishes have teeth
that are shaped
CUTTING to suit their diet.
Serrated teeth are used for
accessory sharp cutting, while pointed teeth
cusp point are used to hold prey.
Many rays have flat teeth
teeth GRIPPING GRINDING for grinding food. As teeth are SWIMMING AND BUOYANCY
arranged lost, they are replaced by new Cartilaginous fishes, such as the hammer-
in rows ones growing behind them. head shark, have an oil-rich liver that adds
to their buoyancy. However, most are still
GILL OPENINGS nostril negatively buoyant and must keep
Most sharks and rays have 5 pairs of gill mouth swimming to avoid sinking.
openings (a few have 6–7) while chimeras
have only one. When water enters the mouth, gills covered Reproduction LIVE BIRTH
the gill slits are closed. As the by flaps Young lemon
water passes out of the open of skin In all cartilaginous fishes, fertilization sharks are
gill slits, the mouth is held closed. occurs internally. The male passes sperm nourished
ELECTRICAL SIGNALS into the female’s cloaca via a modified via a yolk sac
Senses The ampullae of Lorenzini pelvic fin. The young are produced by placenta and are
(seen here on the snout of an one of 3 processes. The females of some born tail-first .
Cartilaginous fishes have acute senses that oceanic whitetip shark) are deep species release leathery egg cases.
can be used to locate prey, even if it is a pores connected to electro- In other species, the young hatch from EGG CASE
long way off or buried by sediment. All receptive nerve endings. the egg inside the female’s body and This egg case contains the
species have a system of pores, called the are then released alive. In the remaining embryo of a small-spotted
ampullae of Lorenzini, which they use to species, the young develop inside catshark. It is anchored
detect the weak electrical signals emitted by a placenta-like structure, from which to seaweed by tendrils
other animals. Most also have an effective they have a direct nutritional connection on the outside.
lateral-line system (see p.469) that responds with the female. In all cases, there is
to very small vibrations, as well as acute no larval stage; instead, the young are
vision and a sense of smell that can detect born as miniature versions of the adults.
odors in even the weakest solutions.

474 CARTILAGINOUS FISHES

Sharks

PHYLUM Chordata Sharks are formidable hunters with few usually have 5 gill slits on either side CONSERVATION
CLASS Chondrichthyes natural predators when fully grown. Classic of their head; a few species have 6
sharks have a streamlined body, powerful or 7 pairs. Over the last few decades, rising
SUBCLASS Elasmobranchi jaws with several rows of sharp teeth, and human populations and falling stocks
(part) Food and feeding of many food fishes have led to an
increase in the popularity of sharks
ORDERS 9 acute senses, especially smell. They range Sharks use various tactics to catch as a food source for humans.
FAMILIES 34 in size from the whale shark (the largest of prey. Predatory sharks rely on short, Compounding this pressure are
SPECIES About 510 all fishes) to squaloid sharks less than 12 in high-speed pursuits through open the growth in the popularity of shark
(30 cm) long. Sharks are most abundant in water, or on ambush and surprise. fishing as a sport and a rise in
Other species simply search an area demand for shark fins in Asian cuisine.
warm temperate and tropical waters, their habitats ranging from for sedentary or slow-moving prey, Millions of sharks are caught annually,
or excavate burrowing animals. Some of which blue shark and piked dogfish
coastal areas to open oceans and deep basins. Some even sharks are scavengers, using an acute (Squalus acanthias) are two of the
sense of smell to locate carcasses most heavily exploited. Conservation
venture into tropical rivers. (they can detect a scent in a solution measures include restricting the
as weak as one part per million). number of fins that can be landed
Anatomy in rows, are replaced throughout The 3 largest species of sharks are unattached, and protection of certain
its lifetime. The shape of the teeth filter feeders, and at least one species and pupping grounds.
Most open-water sharks have a varies according to diet (see p.473), species, the cookie-cutter shark,
torpedo-shaped body that allows although some species have 2 or is an ectoparasite on other sharks, Baby sharks are born or hatch as
them to cut easily through water, more types of teeth. large fishes, and marine mammals. miniature adults, even armed with
although bottom-dwelling species fully functional teeth, and are ready
are more varied and some have a Sharks do not have a swim bladder, Reproduction to hunt. Sharks grow slowly to
flattened body, similar to that of but their large, oil-filled liver adds to adulthood, often taking a decade
rays. Unlike bony fishes, sharks have their buoyancy and helps prevent Coastal bays, lagoons, reefs, and or longer to reach maturity. During
rigid fins that cannot be flexed or them from sinking. Many open-ocean atolls are the favored areas for this time, many young sharks fall
folded, yet their fins are nonetheless sharks need to swim constantly to female sharks to lay eggs or give prey to larger predators.
efficient for steering, propeling, and force water over their gills, but other birth (pupping). These areas provide
stabilizing the body during swimming. species can pump water across a calm, food-rich environment for
A shark’s teeth, which are arranged their gills while motionless. Sharks young sharks to grow and develop.

FISHES

HUNTING

Sharks of the open oceans (such as the blue shark,
shown here) typically have a streamlined body and
a powerful tail fin that propels them quickly through
the water. The mainstays of their diet are squid and
fishes. When hunting, they often circle their prey several
times before attacking from below.

SHARKS 475

Chlamydoselachus anguineus This unusual, deep-water species looks Hexanchus griseus This reclusive, primarily deep-water shark
more like an eel than a shark, with 6 has a broad head and cylindrical body. It
Frilled shark frilled gill slits, a single small dorsal fin, Bluntnose six-gill has 6 gill slits—unlike most other sharks,
and a much larger anal fin. It feeds on shark which have 5—and sharp, comblike
Length 61⁄2 ft soft-bodied animals, such as squid teeth. The bluntnose six-gill feeds on
(Up to 2 m) and fish. Similar to Length 18 ft (5.5 m) rays, squid, bony fishes, and even seals.
Weight Not recorded some long-extinct Weight 1,320 lb It also forages opportunistically for
Breeding Viviparous species, it (600 kg) or more slow-moving animals on the seabed by
Status Near threatened has no close Breeding Viviparous positioning its body, head-down, at an
living relatives. Status Near threatened angle of 45 – 60 degrees to the bottom.
Location E. Atlantic, S.W. With its open mouth directly above the
Indian Ocean, W. and Location Tropical and prey, it probably sucks in its food.
E. Pacific temperate waters
worldwide

teeth with single dorsal fin 6 gill slits
3 sharp near tail
points

powerful
tail

Echinorhinus brucus The most interesting feature of this Squalus acanthias Also known as the spurdog, this small,
shark is the thorny denticles that bottom-dwelling shark lives in coastal
Bramble shark cover its body. These have star-shaped Piked dogfish waters, usually where the temperature
bases and sharp tips, resembling is at or below 59° F (15° C). A slow-
Location N.E. Atlantic, Length Up to 10 ft bramble thorns. Large and slow-moving, Length 31⁄4 ft (1 m), moving fish, it gets its name from the
W. Pacific, Mediterranean, (3.1 m) the bramble shark spends most of its max 51⁄4 ft (1.6 m) spines on the front of its dorsal fins,
Indian Ocean Weight Over 490 lb life foraging on or near the seabed. It Weight 20 lb which can inflict painful wounds. It eats
(220 kg) feeds on other sharks, ratfishes, bony (Over 9 kg) crustaceans, invertebrates, and bony
Breeding Viviparous fishes, cephalopods, and the egg cases Breeding Viviparous fish, and often forms large, single-sex
Status Data deficient of sharks, skates, and rays. It may use its Status Vulnerable schools. Piked dogfishes give birth
large pharynx and small mouth to create
a vacuum effect to suck in prey. Location Worldwide after a gestation period of
outside the tropics nearly 2 years—a long time
dorsal fins
near tail for any shark. FISHES

Oxynotus centrina a compressed, triangular trunk and

Angular roughshark furrowed “lips” with lancelike teeth in

the upper jaw. There is a large spiracle

behind the eye. The expanded body

Length Up to 5 ft cavity and large, oily liver enable it
(1.5 m)
Weight Not recorded to maintain buoyancy, allowing it
Breeding Viviparous
Status Vulnerable to hover above the ocean floor in

search of polychete worms and other

invertebrates. It is one of 5 species in

Location E. Atlantic, sail-like the roughshark Etmopterus spinax
Mediterranean dorsal fins family.
Velvet belly
lantern shark FIRST MEAL

This shark has unusually Length 18 in (45 cm),
high, sail-like dorsal fins maximum 231⁄2 in
with spiny tips. It also has (60 cm)
Weight Not recorded
Squaliolus laticaudus One of the world’s smallest sharks, this Location E. Atlantic Breeding Viviparous
species only has a spine in front of the Status Least concern
Spined pygmy first dorsal fin. It has well-developed
shark light-producing organs (photophores) Like many sharks, young lantern
on its belly and sides, but hardly any on sharks are born with an attached
Length Up to 10 in the back, giving this shark a luminescent This small, shoal-forming shark is one yolk sac. This provides them with
(25 cm) underside. The arrangement of these of more than 30 similar species. It feeds food during their first few days at sea.
Weight Not recorded photophores is thought to eliminate on invertebrates and small fishes. Tiny
Breeding Viviparous shadows, making it harder for predators luminescent organs on its skin produce SPINED FINS
Status Least concern (such as swordfishes) to see it from light, which help attract potential prey or The velvet belly lantern shark has a sharp spine
below. The first known spined pygmy other velvet belly lantern sharks, frighten at the front of each dorsal fin; its second dorsal
Location North Atlantic, sharks were caught in 1908 off Japan, predators, and disrupt shadows, making fin and fin spine are larger than the first.
W. South Atlantic, W. but no further specimens were seen it less conspicuous.
Indian Ocean, W. Pacific until the 1960s. spine

476 CARTILAGINOUS FISHES

Pristiophorus japonicus Heterodontus portusjacksoni Like the horn shark (see below), this shark INSHORE MATING
belongs to a family of 8 species that have
Japanese sawshark Port Jackson shark bulky heads, powerful jaws, and crushing
teeth. Its mouth points downward,
Length Up to 5 ft Length Up to 51⁄2 ft enabling it to feed on starfish, sea urchins,
(1.5 m) (1.7 m) and other seabed animals. The Port
Weight Not recorded Weight Not recorded Jackson shark lives in inshore waters,
Breeding Viviparous Breeding Oviparous and lays large, spiral-shaped egg cases.
Status Data deficient Status Least concern

Location W. North Pacific Location Australia HOME-LOVING
(including Tasmania), This shark maintains a home range and will
New Zealand return to the same area if displaced, though
some migrate to Tasmania in summer.
The Japanese sawshark’s body is During the breeding season,
flattened from top to bottom and has 2 tapering body Port Jackson sharks come close
dorsal fins. It has gills on the sides of its inshore, where they mate and lay
head, rather than underneath, as in rays. eggs. Females sometimes wedge
It has a pair of barbels on a saw-shaped the eggs in rocky crevices.
snout, but it should not be confused with
the superficially similar smalltooth sawfish Chiloscyllium plagiosum Its small size and attractive help it to forage for food; the
(see p.485), which is a ray. Taste sensors appearance have made this shark mouth is located well in front
on the barbels and snout are used to Whitespotted particularly popular with marine of the eyes. The whitespotted
probe the seabed for small fishes or bambooshark aquarists. It has a slender body, bambooshark uses its thickened
invertebrates. Its exceedingly sharp teeth with white spots over a dark pectoral and pelvic fins to clamber
are presumably used for destroying prey Length Up to 37 in background and darker transverse onto rocks.
as well as for defence. Young Japanese (95 cm) bands. Short barbels on its mouth
sawsharks are born with large teeth, but Weight Not recorded white spots
these remain folded while the young are Breeding Oviparous thickened fins
inside the mother to avoid injuring her. Status Near threatened

Location Indo-Pacific,
N. Australia

FISHES

Orectolobus maculatus PERFECT DISGUISE Hemiscyllium galei by dark “saddles” along its back that are
dappled with white spots. There are
Spotted wobbegong Walking shark also prominent dark spots running along
each side of the body. Little is known
Length 6 ft (1.8 m), Length 22 in about its habits, but it has been observed
max 10 ft (3.2 m) (57 cm) at night—at depths of 61⁄2 – 13 ft (2 – 4 m)—
Weight Not recorded Weight Not recorded “walking” along the reef bottom using its
Breeding Viviparous Breeding Probably pectoral and pelvic fins. Like related
Status Least concern oviparous species, it probably hunts for bottom-living
Status Not evaluated fishes and invertebrates, and spends
Location S. Australia Location New Guinea the day resting under rocks or corals.

A large, slow-moving shark with a The spotted wobbegong’s mottled This spectacularly patterned shark
flattened body, the spotted wobbegong coloring and flattened, textured body belongs to a family of sluggish tropical
lives in shallow water close to the shore. provide perfect camouflage on the inshore “bamboo sharks.” It was recently
Instead of actively hunting for food, it seabed. Lured by the weedlike flaps discovered on shallow reefs of Geelvink
rests on the bottom, and ambushes of skin around its snout, lobsters, Bay in Indonesian Papua and is marked
animals that come within striking range. crabs, and octopus may swim right
When the tide falls, it may haul itself up to this shark’s waiting mouth. Stegostoma fasciatum located just behind the snout, points
from one rock pool to another, partly downward, enabling it to feed on
exposing itself to the air. Although SPOTTED AND PATTERNED Zebra shark mollusks that live on the seabed.
generally unaggressive, spotted The spotted wobbegong is elaborately During inactive periods, this shark
wobbegongs can inflict serious patterned, with light, O-shaped spots and Length 91⁄4 ft (2.8 m), rests on the seabed, propped
injuries if accidentally stepped on. dark saddles on an olive background. max 11 ft (3.5 m) up on its erect pectoral fins, facing
Weight Over 66 lb the prevailing current. It is the only
dark saddle (30 kg) species in its family.
Breeding Oviparous
Location Indo-Pacific Status Vulnerable

Beige with brown spots, the zebra
shark has an unusually flexible
body that allows it to hunt out
shrimps, crabs, and small bony
fishes from tight crevices in the
coral reefs where it lives. Its mouth,

SHARKS 477

Rhincodon typus where plankton is abundant, but they SUCTION FEEDING
otherwise lead solitary lives. Little is
Whale shark known about their breeding behavior, In order to feed, the whale shark
or about their movements across the creates a suction effect by lifting its
Location Tropical and Length 39 ft (12 m), world’s tropical seas. head, opening its mouth wide, and
temperate waters max 66 ft (20 m) using powerful throat and gill muscles
worldwide Weight Over 131⁄4 tons GENTLE GIANT to suck in dense patches of plankton.
(12 tonnes) The largest of all fishes, the whale shark is a The water that pours in is filtered for
Breeding Viviparous slow-moving plankton-feeder. Its blue-green plankton, fishes, and squid by screens
Status Vulnerable skin is mottled with white spots whose variable on the shark’s internal gill slits. This
pattern can be used to tell individuals apart. method allows for a large intake of prey.

The whale shark is by far the largest
fish in the world. However, despite
its fearsome appearance, it is quite
harmless to humans, and lives almost
entirely on plankton, filtering its food
with its gills. Its mouth is at the end
of its snout—an unusual position for
a shark—and although its jaws can
be over 31⁄4 ft (1 m) across, they are
armed with the tiniest of teeth. Whale
sharks usually feed by cruising slowly
near the surface, where they show
little alarm at being approached. They
have also been reported to feed in a
vertical position, using their mouths
like giant buckets to trap food. They
sometimes gather in large numbers

Ginglymostoma cirratum the day, the nurse shark spends Mitsukurina owstoni small eyes, and it uses its large FISHES
its time resting on the seabed, in snout to detect the electrical field
Nurse shark rocky crevices, or in caves, where it Goblin shark of its prey. The jaws can be shot
may be found in groups of several forward to catch unsuspecting fish.
Location E. Pacific, Length 93⁄4 ft (3 m), dozen individuals, sometimes lying on Length 11 ft The goblin shark is the only living
W. and E. Atlantic max 14 ft (4.3 m) top of one another. An inhabitant of (3.3 m) member of its family, and it has
Weight Over 330 lb shallow, inshore areas, it can “walk” Weight Over 350 lb been referred to as a “living fossil”
(150 kg) along the seabed using its pectoral (160 kg) due to the fact that it has changed
Breeding Viviparous fins as limbs. The nurse shark is not Breeding Viviparous relatively little in millions of years.
Status Data deficient generally a threat to people but, if Location North Atlantic, Status Least concern It has been found in the Pacific,
provoked, will hold onto its victim E. South Atlantic, S. Indian Indian, and Atlantic oceans, and
with a bulldoglike tenacity. Ocean, W. and E. Pacific is usually found at depths greater
than 330 ft (100 m), though depths of
Formally described in 1898, the goblin 4,300 ft (1,300 m) have been reported.
shark is pink with a wide, flattened
The nurse shark has a very tough skin, snout. It is a deep-water shark with soft fins flabby body
and a pair of barbels below
the mouth for sensing long snout
the invertebrates on
which it feeds. The
small mouth and
large pharynx form a
powerful suction
mechanism, which enables this shark
to draw in prey at high speed. During

Carcharias taurus large mouth It is a large, cumbersome-looking
fish, with a large mouth. The
Sand tiger shark sand tiger shark swallows air
at the surface and retains it in
Location W. and Length Up to 10 ft the stomach to regulate buoyancy.
E. Atlantic, S. Indian (3.2 m) max 13 ft (4 m) A slow, strong swimmer, it feeds
Ocean, W. Pacific Weight Over 330 lb upon a variety of bony fishes, as
(150 kg) well as on squid, crabs, and lobsters.
Breeding Viviparous Groups of sand tigers have been
Status Vulnerable observed working cooperatively
to surround schools of prey. The
Light brown or beige in color with embryos of the sand tiger shark
darker brown blotches distributed are known to be cannibalistic.
randomly over its body and fins, the After hatching inside the mother,
sand tiger shark also has a distinctive, they feed on extra eggs produced
“snaggle-toothed” appearance. by the mother and then on their
smaller sibling embryos. Only
one embryo survives from each
of the 2 uteri.

FISHES 478

SHARKS 479

Carcharodon carcharias will feed on any large creature that it
can catch. It attacks with great ferocity
White shark initially, then may retreat while the injured
prey weakens, after which the shark
Location Temperate and Length 20 ft (6 m), returns to eat in safety. Females, which
tropical waters worldwide; max 26 ft (8 m) are larger than males, give birth to 4 – 14
occasionally in cold waters Weight 21/4 tons live young, 4 ft (1.2 m) or more long. While
(2 tonnes) or more in the uterus, the young are nourished by
Breeding Viviparous eating unfertilized eggs. Although this
Status Vulnerable species is protected in some parts of the
world, it is a popular sport fish, and its
numbers are dropping rapidly.

Also known as the white pointer and triangular gray to black
the great white shark, dorsal fin upper body

this species is blamed crescent-shaped
for more attacks on tail fin
humans than any other

shark—but research

shows that most

human victims

are quickly

released. A powerful swimmer, the

white shark cruises through the water, sickle-shaped pale
either at the surface or just off the pectoral fins underside
bottom, covering long distances very

quickly. It also excels at short, fast SWIMMING POWER
chases, and may leap spectacularly The white shark powers through the water
out of the water. Like other with sideways beats of its tail. Its fixed pectoral
members of its family, it can fins prevent it from nose-diving, and its large

maintain its muscles at an dorsal fin aids stability.

unusually high temperature,

helping it to swim and hunt AWESOME WEAPONS FISHES
more efficiently, especially

in cold water. Although

usually solitary, it may

sometimes be seen in

pairs or small groups

feeding at a carcass,

with larger individuals

eating first. The sharks

may also swim in a

variety of patterns in

order to establish their

dominance hierarchy.

The primary prey of Armed with its large, triangular,

adults is seals, sea lions, coarsely serrated teeth, the white

dolphins, and large shark is superbly equipped for

fishes, including other ripping into the flesh of its unfortunate

sharks—but this species prey. In some situations, this shark

has been known to swim along with

its teeth bared, which may serve to

warn off competitors for food, or rival

sharks intruding on its personal space.

THE GREAT “MAN-EATER”
This very large, formidable-looking shark
is greatly feared as a man-eater, partly due
to the media fascination that followed the
release of the film Jaws. However, according
to the International Shark Attack File, there
have been fewer than 100 confirmed human
deaths due to unprovoked white shark attacks
since records began.

480 CARTILAGINOUS FISHES

Isurus oxyrinchus Also called the blue pointer, mackerel Cetorhinus maximus PLANKTON TRAPPER
shark, or snapper shark, this is possibly
Shortfin mako the world’s fastest shark. The tail is Basking shark To feed, this filter-feeder must move
adapted for speed, with well-defined continuously through the ocean with
Location Tropical Length Up to 13 ft keels on either side of the base— Location Cool to warm Length 33 ft (10 m), its mouth agape, a technique known
waters worldwide (4 m) a common feature in fast-swimming temperate waters worldwide max 49 ft (15 m) as ram-feeding. As the water is
Weight 1,260 lb (570 kg) fishes. This shark has large, unserrated, Weight 65⁄8 tons expelled through the enlarged
or more daggerlike teeth that enable it to stab (6 tonnes) or more gill slits, mucus-laden gill rakers
Breeding Viviparous and grip slippery, fast-moving prey such Breeding Viviparous trap the plankton—which the shark
Status Vulnerable as mackerel, tuna, bonito, and squids. Status Vulnerable quickly swallows.
It can jump several times its length out
of the water when pursuing WATER OUTLETS
prey, or when hooked. This species has very large gill slits that
nearly encircle its head. The gill slits are
keeled The basking shark is the world’s important for breathing and feeding.
tail second largest fish, after the whale
shark (see p.477), and like it, is a extend its jaws unusually far forward to
pointed white harmless, migratory plankton-feeder. snatch at prey, such as medium-sized
snout underside It often feeds at or near the surface, bony fishes, squids, or shrimps. The
its huge first dorsal fin and tail fin crocodile shark is thought to migrate
Megachasma pelagios FEEDING AIDS projecting above the surface. Although vertically, following its prey toward the
primarily solitary, groups of up to 100 surface at night and then sinking again
Megamouth shark may gather to feed in areas where at dawn, its large eyes enabling it to see
plankton blooms are dense. in dimly lit conditions. Like the sand
tiger shark, this species may be an
Location W. and E. Length Up to 18 ft intra-uterine cannibal, with embryos
Atlantic, S. Indian Ocean, (5.5 m) eating each other before the survivors
W. and E. Pacific Weight Up to 1,740 lb are born. However, this is not known for
(790 kg) certain, though they do eat other eggs
Breeding Unconfirmed and only 2 pups are produced from
Status Data deficient each uterus. Pups are about 16 in
(40 cm) long at birth and may be born
FISHES The megamouth is one of the world’s Distinctive coloring in and around
least-known large sharks. It was this shark’s huge mouth may at any time of the year.
discovered in 1976 when one specimen be aids to feeding. A luminescent
became trapped by a ship’s underwater stripe on the margin of the upper
equipment off the Hawaiian islands. jaw and a silvery roof to the
Around 60 specimens have been seen mouth—visible as the shark swims
since. This shark is characterized by along with jaws open—may serve
an extraordinarily large mouth, which to attract prey.
facilitates filter feeding. One of only
3 plankton-eating sharks, the has few enemies, sperm whales (see Pseudocarcharias kamoharai
megamouth shark is believed to follow p.260) being one of the few predators
the movement of plankton, rising from big enough to tackle this huge fish. Crocodile shark
deep water to the surface at night and However, the megamouth is harmless
returning to the depths during the to humans.
day. Its great size means it
Length 31⁄2 ft (1.1 m)
or more
Weight Not recorded
Breeding Viviparous
Status Near threatened

Location Open tropical
waters worldwide

COLOR CONTRASTS This small, cylindrical shark is an
The megamouth’s back is oceanic species. It has a pronounced
uniformly gray to blue- snout and large teeth, and is able to
black in color, while the
underside of the body is whitish.
A white stripe runs along the
margin of the upper jaw.

Alopias vulpinus rest of the body. long upper
The shark uses this lobe of tail
Thresher shark extended lobe to herd fishes
together into tight schools, and shark uses its tail to defend itself
Location Temperate and Length Up to 18 ft then stuns them with powerful swipes against marine predators as well. abrupt,
tropical waters worldwide (5.5 m) of the tail. A number of threshers The thresher shark is one of 3 pointed snout
Weight 990 lb may cooperatively encircle schools similar species, and is brown with
(450 kg) or more of fishes such as herring and small a white underside. It is generally
Breeding Viviparous tuna, corraling them with their tails confined to deeper waters, but
Status Vulnerable before the final attack. The thresher the young and some adults may be
has also been known to use the found in shallower regions around
tail as a means of defense against pointed
humans. Large individuals boated pectoral fins
by fishermen may slap furiously
The thresher shark is uniquely with their tails. It is likely that this coasts. It may, at times, congregate
shaped, the upper lobe of its tail in schools made up entirely of either
fin being almost as long as the males or females.

SHARKS 481

Mustelus mustelus or gray-brown above and lighter below, Triakis semifasciata
with few or no markings. This shark’s flat,
Smooth-hound slab-shaped teeth are designed for Leopard shark
crushing mollusks, crabs, lobsters, and
Location E. Atlantic, Length Up to 51⁄4 ft other invertebrates, as well as bony fishes. Location E. North Length Up to 61⁄2 ft distinctive black markings
Mediterranean (1.6 m) It often feeds in schools. Active after dark, Pacific (2 m)
Weight 29 lb (13 kg) the smooth-hound generally swims near Weight Up to 71 lb background. Its powerful jaws and
or more the sea bed in coastal waters, including (32 kg) small, sharp teeth help it to capture
Breeding Viviparous the intertidal zone. One of nearly 30 Breeding Viviparous a wide variety of prey, including
Status Vulnerable similar species worldwide, this shark is Status Least concern burrowing invertebrates that it pulls
commercially fished around Europe, the out by quickly grasping any exposed
Mediterranean, and West Africa. parts; the shark is thought to feed both by
day and by night. There are 4 more similar
slender short head species but the leopard shark’s markings
body are distinctive.

The shiny and The leopard shark is distinguished by a
relatively smooth skin of pattern of conspicuous black markings on
the smooth-hound is gray its sides and fins, over a light brown

Cephaloscyllium ventriosum Scyliorhinus canicula relatively smooth skin

Swellshark Small-spotted
catshark
Length Up to 31⁄4 ft
(1 m) Length Up to 31⁄4 ft slender numerous dark gill
Weight Not recorded (1 m) body spots aid camouflage slits
Breeding Oviparous Weight 61⁄2 lb (3 kg)
Status Least concern or more
Breeding Oviparous
Location E. North and Status Least concern covered with many dark spots and fewer bony fishes, close to the seabed. Females
South Pacific light or white ones. The colors and deposit egg capsules on beds of algae;
patterns vary greatly, and help conceal these are often washed up on the shore
Location E. North Atlantic, this shark from predatory fishes. Normally and are commonly known as mermaid’s
Mediterranean solitary, when it does form schools, males purses. They are rectangular, with tendrils
and females are rarely found together. at each corner that anchor them to the
When threatened, the swellshark Also called the lesser spotted dogfish, This shark is active by both day and night, seaweed. In Europe, the small-spotted FISHES
may expand itself by taking in water this is the commonest European shark. It hunting by scent and electrical sense for catshark is commercially fished for its oily
or air. In addition to making it appear is small and slender, with a smooth skin worms, mollusks, crustaceans, and small liver as well as for food.
more imposing to potential predators,
this defensive technique allows the Carcharhinus leucas small, rounded large first stubby, rounded
shark to wedge itself tightly into crevices second dorsal fin dorsal fin snout
for safety. This large member of the Bull shark
catshark family has a variable pattern
of small spots and dark brown markings. Length Up to 11 ft freshwater whaler, or Swan River large, angular large
Highly nocturnal, it usually lies (3.4 m) whaler, has 2 spineless dorsal fins and pectoral fins gill slits
motionless in crevices by day, and Weight 510 lb (230 kg) a streamlined shape. It is one of the few
swims slowly through algae beds or or more sharks that often swims up rivers—it
near the seabed at night, presumably Breeding Viviparous has been found more than 1,870 miles
preying on diurnal fishes that are less Status Near threatened (3,000 km) from the sea in the Amazon.
alert at night. The swellshark is one Its diet is unusually wide-ranging and
of about 8 similar species. includes bony fishes, invertebrates,
mammals, and other sharks, including
Location Tropical and
subtropical waters
worldwide

Like all members of the extensive young bull sharks. One of the world’s
requiem shark family, the bull shark, most dangerous sharks, the bull
also known as the river whaler, shark has been involved in numerous
provoked and unprovoked attacks
on humans.

Galeocerdo cuvier A known man-eater and one of the indicate that it may also cross large EATING HABITS
world’s most dangerous sharks, expanses of open ocean. It makes
Tiger shark the tiger shark has distinctive teeth forays from the tropics to higher A primarily nocturnal hunter,
shaped like a cockerel’s comb, and latitudes during the warmer months. the tiger shark has the most
Location Tropical and Length 18 – 25 ft a head that is disproportionately The tiger shark gives birth to fully indiscriminate diet among sharks:
warm temperate waters (5.5 – 7.5 m) large for its slender, streamlined body. developed young; females may it employs quick bursts of speed
worldwide Weight 1,990 lb This shark generally prefers coastal secrete uterine “milk” to provide to catch live prey, such as fishes
(900 kg) or more waters, often moving inshore to feed additional nutrition for the embryos. and a variety of marine reptiles,
Breeding Viviparous at night, and sometimes exploring Although not highly valued for its flesh, invertebrates, and mammals. It
Status Near threatened the very shallow waters of bays and it is often harvested in commercial also scavenges on carrion, and
estuaries. Recent studies, however, shark fisheries. may even feed on garbage.

tigerlike large upper tail
stripes lobe for speed

large head white underside STRIPED YOUNG
The juveniles and the young adults of this
species are conspicuously marked with vertical,
tigerlike stripes. These may fade or be absent
in adults.

482 CARTILAGINOUS FISHES

Carcharhinus melanopterus Indo-Pacific region. This shark usually Triaenodon obesus CONSERVATION
occurs in shallow water, and the dorsal
Blacktip reef shark and upper tail fin may project above the Whitetip reef shark Despite their reputation for being
surface of the water. People wading dangerous, sharks have more to
Location Tropical Length Up to 61⁄2 ft and swimming are frequently bitten, Location Tropical Length 51⁄4 ft (1.6 m), fear from humans than humans do
Indo-Pacific (2 m) but though curious of divers, it is more Indo-Pacific max 7 ft (2.1 m) from sharks. Many of the world’s
Weight Over 99 lb circumspect with them. The blacktip Weight Over 40 lb inshore species—including the
(45 kg) reef shark has a streamlined body, (18 kg) whitetip reef shark—have been
Breeding Viviparous which makes it an active and powerful Breeding Viviparous heavily overfished in recent years,
Status Near threatened swimmer. As its name suggests, the Status Near threatened and are rapidly declining as a result.
tips of the fins are black. Sharks are often fished for their fins
alone, the rest of the animal being
The blacktip reef shark is black-tipped fins While most sharks must swim thrown away.
a familiar species continuously, mouth agape, to force
of shark in capable of a powerful bite and may oxygenated water across their gills, the WHITE MARKERS
the tropical attack humans if provoked. Yellowish to whitetip reef shark, or blunthead, can This slender shark has distinctive white
light brown in color, this fish has large pump water across its gills and can tips on its dorsal fin and upper tail lobe.
Negaprion brevirostris fins and an abrupt snout. The lemon therefore rest on the ocean floor. It
shark is adapted to survive in brackish relies heavily on sound and smell for
Lemon shark waters and areas of low oxygen. It feeds catching prey—often associating the
mainly on bony fishes, guitarfishes, and sound of boat engines with the
Location E. Pacific, Length Up to 11 ft stingrays, but may also eat crustaceans opportunity to steal fishes, it doggedly
W. and E. Atlantic (3.4 m) and molluscs. Adults are most active at pursues speared fishes and may
Weight Over 410 lb night; the juveniles by day. bite fishermen. Nevertheless,
(185 kg) it is generally nonaggressive.
Breeding Viviparous
Status Near threatened white-tipped
dorsal fin

FISHES The lemon, or sharptooth, shark adapts
well to captivity and hence is one of the
most-studied members of the requiem
shark family. Normally unagressive, it is

Prionace glauca It migrates seasonally following complex Squatina dumeril lightning speed at unwary prey,
consisting chiefly of crustaceans and
Blue shark inshore and transoceanic routes. Blue Sand devil other fishes. One of about 14 similar
species, the sand devil (or angelshark)
sharks are usually wary of divers but Length Up to 5 ft is commercially fished for its flesh,
(1.5 m) skin, and oil.
have been known to attack humans. Weight Over 60 lb
(27 kg)
Length 12 ft (3.8 m) They sometimes circle potential prey Breeding Viviparous winglike flattened
or more Status Data deficient pectoral fins body
Weight Over 440 lb before attacking, and large numbers may
(200 kg)
Breeding Viviparous gather around a whale or porpoise
Status Near threatened
carcass in a feeding frenzy, biting at Location W. North Atlantic

chunks of floating debris. They may

Location Tropical and also be seen following trawlers, and
temperate waters
worldwide feeding on the

trapped fishes. cobalt-blue body This flattened fish is often found partially
buried in sand on the sea floor,
Although possibly the widest winglike pectoral fins its nondescript coloration
ranging shark, this species is serving as camouflage.
threatened by overfishing. Mainly a sit-and-wait predator, it

uses its protrusible mouth to strike with

Sphyrna zygaena Found in inshore and several species do so around UNIQUE ANATOMY
offshore waters, it is often seamounts. These aggregations
Smooth hammerhead seen at the surface, with its large may be for feeding or breeding. As The hammerheads’ strange
dorsal fin slicing through the water. hammerheads are top predators, it is head anatomy provides several
Location Tropical, Length Up to 13 ft Like all hammerheads, it is generally highly unlikely that these groups form
subtropical, and temperate (4 m) shy but is potentially dangerous. It for protection from other predators. advantages, including all-round
waters worldwide Weight Up to 880 lb feeds on a wide variety of fishes, vision, and space for more
(400 kg) including other sharks. Unlike most IDENTIFYING FEATURES electrical receptors with which it
Breeding Viviparous other sharks, hammerheads Species of hammerhead sharks can be difficult can track prey. Some species use
Status Vulnerable often form schools, and to tell apart. In the smooth hammerhead there the “hammer” to pin down stingrays
are no indentations along the front of the head. while they feed on them.
narrow
head flaps long upper
tail lobe

The smooth hammerhead is one
of 8 species of hammerhead sharks,
instantly identifiable by their bizarre
heads, which have eyes at the end
of winglike extensions, or “hammers”.

RAYS 483

Rays

PHYLUM Chordata Broad bodies and winglike fins distinguish Reproduction CHIMERAS
CLASS Chondrichthyes rays from other cartilaginous fishes. Their
flattened shape is generally an adaptation for Like sharks, all rays mate and Ratfishes, rabbitfishes, and their
SUBCLASS Elasmobranchi life on the seabed, although several species, fertilization is internal. A large group relatives—collectively known as
(part) including mantas and eagle rays, swim in open of rays, particularly those commonly chimeras—make up a small group of
water. Rays are found throughout the world but called skates, release large, leathery cartilaginous fishes that are distinct
ORDERS 4 are particularly diverse in the tropics, while a egg capsules containing one or more from sharks, skates, and rays.
FAMILIES 17 group of egg-laying rays, called skates, are developing offspring. All other rays They form the class Holocephali,
SPECIES About 650 give birth to live young. The eggs containing 52 species. Their soft,
hatch inside the female’s body and scaleless bodies are usually long and
widespread in temperate waters. Most rays live the young live off their yolk sacs until narrow, and they have a bulky head
large enough to be released. In some with large, iridescent eyes. Found in
along coasts, but some range far into deep-sea basins. Although species, the embryos are further the waters of the Indian, Atlantic, and
nourished by a fluid manufactured Pacific, they live at depths up to
some rays range between fresh- and saltwater estuaries, there are by the mother and produced by the 26,400 ft (8,000 m).
membranes of the uterus.
others that live exclusively in freshwater.

Anatomy invertebrates, although prey varies
considerably between species.
Rays have flat bodies; a long, thin tail; These fishes have teeth that are
and large pectoral fins, which are used designed to grasp, rasp, or crush
for propulsion. Larger species flap food, and interlock in a pattern
these fins like wings. Unlike sharks, they known as pavement dentition.
generally have a much smaller liver in A few species, such as mantas,
proportion to their body, as most live are filter feeders that strain small
on the sea bed and have no need for a fishes, invertebrates, and
buoyancy device. Most species are plankton with their
coloured to blend into the seabed, but sievelike gill rakers.
they may also partially bury themselves
in the sediment. As their mouth is on FISHES
the underside, they breathe through
openings called spiracles—one behind SCHOOLING
each eye. Water enters the spiracles
and leaves through the gill openings. Most rays lead sedentary lives or move slowly
In addition to a covering of tiny placoid along sea or riverbeds. However, some, such
scales, many rays have large prickles or as these bat rays, inhabit open waters,
thornlike scales for protection and to propelling themselves with their large pectoral
provide grip while mating. While most fins. They form schools that may contain
rays are harmless, stingrays have a several hundred individuals.
venomous barbed spine on the tail
that can inflict a painful wound.

Feeding

All species of rays are carnivorous,
and most are predators on small,
bottom-dwelling fishes and

Raja undulata Raja clavata Dipturus batis of many skates. The female lays around
10 egg cases in pairs every year. These
Undulate skate Thornback skate Blue skate are very large and up to 8 in (20 cm) long,
with a dark, thick, flexible shell and
Location E. Atlantic, Length Up to 31⁄4 ft Location E. Atlantic, Length Up to 35 in Location E. Atlantic, Length Up to 81⁄4 ft a pair of tendril-like thorns on either
Mediterranean (1 m) Mediterranean (90 cm) Mediterranean (2.5 m) side. Unlike most other skates, the
Weight 61⁄2 – 83⁄4 lb Weight 41⁄2 – 83⁄4 lb Weight 110 – 220 lb blue skate is active by day and night.
(3 – 4 kg) (2 – 4 kg) (50 – 100 kg)
Breeding Oviparous Breeding Oviparous Breeding Oviparous It feeds on seabed animals,
Status Endangered Status Near threatened Status Critically especially fishes, worms,
endangered and crustaceans.

wavy dark lines The thornback skate occurs in marbled Also known as the common skate,
edged with shades of brownish gray with a very this species is anything but
white spots varied pattern of lighter spots and common and is severely depleted
blotches; its underside is white. Both throughout its range. While brown
Found on mud or sexes have big spines on their back— and spotted, it has a distinct
sand at depths of 650 ft hence the common name of this bluish gray tinge to its paler
(200 m), the undulate skate relies on its species. As with most rays, it lies underside, hence the name. It
intricately patterned, reddish or brown camouflaged on the has a pointed snout and a
skin to hide from predators. During ocean floor.
the breeding season, females lay up concave front edge to the
to 15 eggs, each in a tough capsule large, wide wings, which is typical
up to 31⁄2 in (9 cm) long. spines

single row of spines
along body and tail

484 CARTILAGINOUS FISHES

Manta birostris be a distinct species named the reef FUNNELING FOOD
manta ray (Manta alfredi). During the
Giant manta ray breeding season, the male chases the Giant manta rays have large,
female, swimming beneath her so that flaplike cephalic lobes, and they
Length Up to 23 ft their undersides face each other, and use these to funnel prey into their
(7 m) mouths. The water passes out
inserts one of his claspers. The through the ray’s gills, but
Weight Up to 2 tons female usually gives birth to one the prey is trapped on transverse
(1.8 tonnes) spongy plates that bridge the gaps
or 2 young per year, each between the gill bars. Mantas eat
Breeding Viviparous about 4ft (1.2m) wide. small, schooling fishes, as well
as smaller planktonic animals.
Location Tropical and Status Vulnerable

sometimes warm temperate
waters worldwide

Measuring up to 23ft (7m) across, the triangular flaplike
manta—also known as the devil ray— pectoral fins cephalic lobes
is the world’s largest ray, swimming “wingspan” UNDERWATER FLIGHT
through the open ocean like a large over 21 ft The manta has large, triangular
bird on slowly flapping wings. However, (6.5 m) pectoral fins with pointed tips, and
despite its sinister look, it is a harmless a short tail without a fin or sting. In
plankton-eater, filtering food with its gills. normal circumstances, its fins beat up
Its mouth, unlike those of other rays, is and down about once every 4 or 5
positioned in front of its body, allowing seconds, but the manta can accelerate
it to feed continuously as it moves along. rapidly, sometimes somersaulting out
Normally a leisurely swimmer, it can of the water and crashing back onto
suddenly accelerate if threatened, and the surface with a massive impact.
can even leap out of the water, possibly
to avoid predators. Mantas are usually
solitary, although they sometimes swim
in small, loosely organized schools. They
prefer warm waters, and are mostly found
in the tropics. In 2009, the smaller coastal
mantas often seen by divers were found to

FISHES Rhinobatos productus those of a typical ray, but the rest or mud. It feeds at night on small Urolophus halleri
of its body is cylindrical, like that of a bottom-dwelling fish, clams,
Shovelnose guitarfish shark. Found in the warmer areas of crustaceans, and worms, which it Round ray
the eastern Pacific Ocean, it tends to uncovers from the seabed. The female
Length Up to 5 ft move inshore in the summer months. produces 5 – 25 young, which are about Length 20 – 231⁄2 in
(1.5 m) The shovelnose guitarfish is generally 6 in (15 cm) long at birth. (50 – 60 cm)
Weight 33 – 40 lb solitary but sometimes gathers in large Weight 41⁄2 – 83⁄4 lb
(15 – 18 kg) numbers for breeding. Found in shallow cylindrical, sharklike body (2 – 4 kg)
Breeding Viviparous water around beaches, bays, estuaries, Breeding Viviparous
Location E. Pacific Status Near threatened and reefs, it lies partially buried in sand Location E. North Pacific Status Least concern

Named for its unusual shape, the triangular Unlike typical stingrays, the round ray
shovelnose guitarfish has a broad tail fin and its relatives, sometimes known as
head with a clear, cartilaginous stingarees, have an almost circular
area on either side of the snout. rounded pectoral fins body. The body is very flattened, and
Its pectoral fins are wide, like the tail is relatively short, with a rounded
fin at its tip. During warm seasons, large
Taeniura lymma mishandled. Although mainly diurnal, it is LYING IN WAIT numbers sometimes move into shallow
sometimes active at night. It moves into beaches where they may sting bathers
Blue-spotted shallow areas with the advancing tide to Blue-spotted stingrays normally who are unfortunate enough to step on
stingray feed on small fishes and invertebrates, actively forage for food, but they them. As with other stingrays, the sting
especially crustaceans and worms. It is rest with their bodies largely hidden of this can be intensely painful.
Length Up to 61⁄2 ft often found in sandy areas next to reefs, by mud or sand, with just their eyes
(2 m) and rests in reef caves and crevices projecting above the surface. In sting partway
Weight Up to 66 lb when not feeding. The female gives shallow water, hidden rays are along tail
(30 kg) birth to 3 – 7 young and, like the South easily stepped on.
Breeding Viviparous American freshwater stingray (see tail fin
Status Near threatened opposite), she nourishes her young by stripes
Location Indo-Pacific secreting uterine “milk.” The colorful on tail
appearance of the blue-spotted stingray
One of the most handsome members of has made it a popular fish in the
the stingray family, this species has blue aquarium trade and a favorite subject
spots scattered over its body. In addition, of underwater photographers.
it has blue stripes along the side of its tail
and a lighter underside. Like all stingrays, round small pelvic
this fish has a toxic spine located at body fins
the base of its tail and is capable of
inflicting a nasty sting if stepped on or blue spots
on body

RAYS 485

Myliobatis aquila with a massive, crushing toothplate. Potamotrygon motoro an entire family of stingrays that evolved
in freshwater from a marine ancestor.
Common eagle ray Like its numerous relatives, which South American The short tail of the South American
freshwater stingray freshwater stingray has no fin, and its
are found in oceans all over the small pelvic fins are tucked under its
pectoral fins. This stingray has few
world, it feeds on the seabed, but predators, except some larger fishes
and caiman, and feeds on small fishes
Length 81⁄4 ft (2.5 m) is equally at home in open water. and invertebrates.
or more
Weight 44 – 66 lb The common eagle ray feeds brownish color with
(20 – 30 kg) dark spots aids
Breeding Viviparous on on a wide variety of small Length Up to 31⁄4 ft camouflage
Status Data deficient (1 m)
animals, and it excavates these Weight 61⁄2 – 11 lb finless tail
(3 – 5 kg)
from the sediment by flapping Breeding Viviparous rounded
Status Data deficient pectoral fins
Location E. Atlantic, its fins, or by blowing jets
Mediterranean, pectoral fins. Although such shocks
S.W. Indian Ocean of water to clear away are not known to be fatal to humans,
contact with this ray can be dangerous.
mud and sand. A good Location South America Active during the day and in the evening,
the marbled electric ray generally lies on
swimmer, the common the ocean floor, well camouflaged against
the sediment. Females give birth to
eagle ray can leap clear 5 – 35 young every year; larger females
produce more young.
The common eagle ray has tapered of the water’s surface
pectoral fins, a blunt snout, and an
exceptionally long tail armed with a to escape attack from This round-bodied ray is the
venomous spine. The body of this fish most common and widespread
varies in color from grayish brown predators. Female freshwater stingray in South
to bronze or blackish, and its mouth, America. It is a member of
positioned on its underside, is equipped common eagle

rays give birth to

3 – 7 live young venomous
each year. spine

bill-like snout flattened body Torpedo marmorata

Marbled electric ray

pointed Length Up to 31⁄4 in
pectoral fins (1 m)
Weight 22 – 29 lb
Location E. Atlantic, (10 – 13 kg)
Mediterranean Breeding Viviparous
Status Data deficient

Many cartilaginous fishes use weak brownish FISHES
electrical signals to detect prey, but gray color
this ray can generate shocks, powerful acts as
enough to kill other fishes, from specially camouflage
modified gill muscles at the base of its
equipped with large, crushing teeth,
Pristis pectinata slits are located on the underside of Hydrolagus colliei and scaleless, slippery skin. Males
the head. While typically found in the have a retractable, clublike appendage
Smalltooth sawfish shallow, sandy, and muddy water of Spotted ratfish between their eyes, which is used to
beaches and bays, the smalltooth grip with during mating. Adults are
Location W. and E. Length 20 ft (6 m) sawfish may occasionally be found Length Up to 37 in usually dark brown or grayish, with
Atlantic, Indo-Pacific or more at the mouth of rivers and freshwater (95 cm) green, yellow, or bluish hues, and
Weight 550 – 660 lb streams. It feeds by patrolling the Weight 41⁄2 – 13 lb they have silvery white spots along
(250 – 300 kg) seabed and sucking up small organisms, (2 – 6 kg) their sides. Spotted ratfishes are slow
Breeding Viviparous sometimes using the saw to probe the Breeding Oviparous swimmers, and rely on a venomous
Status Critically bottom or excavate buried prey. It also Status Least concern dorsal spine as their main defense
endangered slashes into schools of fishes with its against attack. They patrol the ocean
sawlike snout, feeding on dead or floor in search of prey, feeding on
maimed fishes that fall to the bottom. The Location E. North Pacific invertebrates and seabed fishes.
female gives birth to 15 – 20 young, which Females usually lay 2 – 5 eggs a
Also known as the wide sawfish, this are born with a protective membrane over Ratfishes are found in deep water year; each one is contained in a long,
long-bodied fish has a remarkable their saws, an adaptation that protects in most parts of the world, but the spindle-shaped case. Ratfish liver
snout, which is about one-quarter of the female while giving birth. At first, the spotted ratfish is one of only 2 species contains an oil that was once used
its body length and has 24 – 32 pairs young live in nursery areas, which are that live on the Pacific coast of North as a machine and gun lubricant, but
of pointed teeth on either side. Although usually found in shallow water where America. Like other ratfishes, it has is today of little commercial value.
it is equipped with this sawlike snout, there is plenty of vegetation. Loss of a disproportionately large head,
it is not generally aggressive and is these areas due to coastal development and a downward-facing mouth that is
dangerous only if mishandled by divers. has contributed to their decline. One of
The smalltooth sawfish has a flattened 6 similar species, the smalltooth sawfish
head with small eyes, which have is subject to overfishing in many areas
spiracles situated above and slightly because its flesh is edible and the saw is
posterior to them. The mouth and gill sold as a souvenir.

spiracle above triangular
the laterally dorsal fins
situated eye

snout 30 percent stout pectoral fins
of body length

486 BONY FISHES

Bony fishes

PHYLUM Chordata Bony fishes form overwhelmingly the largest and Senses
most varied group of fishes, accounting for more than
CLASS Osteichthyes 9 out of 10 species. Of the 8 classes of fishes, they Most bony fishes have keen senses of vision and hearing. Both of
evolved most recently and are usually regarded as the
ORDERS 67 most advanced. They exhibit an astonishing variety these senses are used in communication and social interaction.
of size, color, and shape. All bony fishes have a light
FAMILIES 481 but strong internal skeleton, made entirely or partly They are also thought to contribute to bony fishes’ well-developed
of bone, which supports flexible fins that enable the
SPECIES About 31,000 fish to control its movements with precision. Most ability to school. The eyes are generally set on the sides of the head,
also have a gas-filled swim bladder that allows them
CLASSIFICATION NOTE to adjust their buoyancy within narrow limits. Bony lateral-line pore giving each fish a wide field of
fishes are found in almost all aquatic habitats, view. Rods and cones in the
Bony fishes account for more including marshes, lakes, rivers, coasts, reefs,
species than any other class of and deep oceans. Many have adapted to extreme retina give them good color
vertebrates. They are split into conditions, and species of bony fishes occur in
2 subclasses: fleshy-finned high-altitude lakes, polar coasts, hot springs, vision, and many species have
fishes (Sarcopterygii) have fins high-salinity ponds, acidic streams,
that look like flippers, joined to and low-oxygen swamps. bright coloration, which helps
the body by fleshy lobes; ray-
finned fishes (Actinopterygii) them attract mates and
have fins supported by bony
fin rays. Ray-finned fishes are defend territory. Sound is an
by far the larger group and
are divided into 9 superorders. LATERAL LINE effective means of underwater
Classification of bony fishes
is in a state of constant The lateral-line system, which is used communication. Some species
change as new species are
discovered and zoologists to detect movement vibrations, is highly of bony fishes can produce
learn more about the
relationships between them. developed in bony fishes. This is thought sounds, either using their swim

to be another reason why they can move bladder or by rubbing parts of

effectively in large schools. their body together.

FISHES Anatomy

The skeleton of a bony fish consists of 3 main units: the skull,
backbone, and fin skeleton (see below). The gills of bony fishes
are paired and located behind the head and below the cranium.
Unlike in other groups of fishes, the gill openings are covered by a
bony flap, called the operculum, and the lower gill chamber contains
bony supports, called branchiostegal rays. These 2 structures enable
the fish to take water into its mouth and then pump it over its gills: the
branchiostegal rays help open the mouth and regulate intake, while
the operculum acts as a seal over the gills to control the outflow.
In this way, a bony fish can respire while stationary. Most bony fishes
have light, flexible, cycloid or ctenoid scales (see p.468), usually covered
by a thin layer of skin that secretes mucus. The mucus repels parasites
and disease-causing organisms; in some species, it also prevents
moisture loss. Other bony fishes have large, protective scales or no
scales at all (although their skin still produces mucus).

neural spine of vertebra streamlined
skull
fin ray
symmetrical tail SKELETON SWIMMING

SCHOOLING A bony fish’s skull encases the brain and supports the jaws Bony fishes, such as these French grunts,
can maneuver precisely. Each fin ray is
and gill arches. Teeth may be found in the jaws, in the throat, controlled by a separate set of muscles
so that it can move independently of
on the roof of the mouth, or on the tongue. The backbone, the others. The symmetrical tail typical
of bony fishes is an efficient tool for
rib consisting of articulated vertebrae that are linked to the propelling the fish through water.
bony fin vertebral
base column ribs in the abdomen, provides support for the body. Each

fin consists of a bony base embedded in the body, from which

operculum rodlike structures extend to form the outer fin.

1 2 3 4 5

ATTRACTING PREDATORS STAYING TOGETHER CLOSING RANKS USING THE LIGHT ON THE ATTACK
A marlin has isolated a shoal of As the marlin swims toward the While the marlin circles below them, The marlin keeps the shoal near The marlin repeatedly attacks. If the fish
yellowtail horse mackerel between shoal, the mackerel repeatedly the mackerel pack themselves even the surface and picks off fish are forced to split, they will try to rejoin
itself and the surface. change direction, staying together. more closely together. from below. the largest group.

BONY FISHES 487

Buoyancy gas dorsal aorta swim Reproduction
gland bladder
Most bony fishes control their buoyancy using In most bony fishes, fertilization occurs outside the body but in
an outgrowth of the intestine known as the rete intestine ovale a few species it is internal. Marine fishes that live in open water
swim bladder. The volume of gas in the mirable usually produce eggs that float as part of the plankton, often in
swim bladder is affected by water pressure large numbers because only a small number will survive. Coastal
(depth), but the fish can maintain correct SWIM BLADDER marine and freshwater fishes tend to produce fewer eggs, which
buoyancy by adding and subtracting gas. Apart from some primitive species, most bony are laid in the sediment, in nests, or attached to plants. A few
The swim bladder of a freshwater fish has a fishes adjust their buoyancy by moving gas species care for their eggs or even their young. This usually
greater capacity than that of a marine fish, between the bloodstream and the swim bladder. takes the form of protecting them from predators. Bony fishes
because freshwater is less dense than sea water include some hermaphroditic species, which have both male
and does not give as much support to the fish’s Gas enters the bladder through the gas gland, and female reproductive organs. Others change sex during
body. Having a swim bladder means that bony which is supplied with blood by a network the course of their adult life, either from male to female or vice
fishes (unlike cartilaginous fishes) do not need of capillaries called the rete mirable. versa. These alternative strategies are all designed to maximize
to use their fins for buoyancy control and, so have Using another structure, known
been free to modify them for many other uses. as the ovale, gas is removed reproductive output using
from the bladder minimum energy.
and reabsorbed
into the blood.

PARENTAL CARE

The male yellowhead jawfish incubates its
eggs by storing them inside its mouth.
Some other bony fishes (including
some cichlids) use their mouth
to protect their young
from predators.

LARVAE FISHES

Most bony fishes hatch from eggs
and begin life as larvae. These

larvae of the European eel are in
the process of metamorphosis,
during which they are
referred to as glass eels.

Schooling STAYING TOGETHER

Many bony fishes swim in large groups that often contain tens of thousands of Schooling fishes pack tightly together, each one typically keeping a distance to its
individuals. When the fishes are grouped together but behave independently, the group nearest neighbor of no more than one body length. A silvery coloration (seen
is referred to as an aggregate. In a school, however, the movement of the fishes is much in these sweepers) helps the fishes see each other’s movements because a small
more harmonized, to the extent that the school resembles a single organism. Only bony change in direction produces a large change in the amount of light reflected.
fishes can swim in this coordinated way. Each fish usually follows a course parallel to its
neighbors, maintaining its position using its vision, hearing, and lateral-line system.
Fishes in a school are safer than solitary ones, because there are more individuals to
look out for danger and it is difficult for a predator to pick out a single fish from a large
mass (see left). It is also easier for fishes in a group to find mates and locate food.

488 BONY FISHES

Fleshy-finned fishes AIR-BREATHING FISHES

PHYLUM Chordata Fleshy-finned fishes have enlarged fleshy fin bases that consist of Larval South American lungfish have gills, while the
CLASS Osteichthyes muscles connected to an internal skeleton. Some species use these fins adults have 2 lungs and can only breathe air. When
to “walk” on the seabed as well as for swimming. Fleshy-finned fish in its breeding burrow, the male provides extra oxygen
SUBCLASS Sarcopterygii are divided into 2 groups (orders), the lungfish and the coelacanths. for its young by releasing it into the water from feathery
structures on its threadlike pelvic fins.

ORDERS 2 Lungfish are thought to be the closest living relatives of the

FAMILIES 4 4-legged animals. Somewhere in the ancestry of fleshy-

SPECIES 48 finned fish and tetrapods, fleshy fins developed into

limbs capable of movement on land. The eellike

lungfish have one or two primitive lungs as well as gills and so can

breathe air if necessary They can live in oxygen-poor swamps and

even survive out of water. One species, the West African lungfish, can

reside in a mud cocoon at the bottom of a dry lake, awaiting the next

wet season to replenish the water. The other group, the coelacanths,

were thought to be extinct since the time of the dinosaurs until

discovered in 1938; they live in deep areas of the Indian Ocean.

Latimeria chalumnae out over 65 million years ago. It is found Neoceratodus forsteri through its gills, when oxygen levels in
at depths of 500 – 2,300 ft (150 – 700 m) the water fall, it gulps air at the surface,
Coelacanth along rocky slopes with submarine Australian lungfish breathing through its lung. Unlike
caverns, swept by strong oceanic African and South American lungfishes,
Location W. Indian Ocean Length 5 – 6 ft currents. It has large, thick, heavy Location E. Australia Length Up to 6 ft this species has paddle-shaped, paired
(1.5 – 1.8 m) scaling with iridescent white flecks, (1.8 m) fins. Its dorsal and anal fins are
Weight 145 – 220 lb muscular paired fins, and an unusual Weight Up to 99 lb continuous with its tail fin. The
(65 – 98 kg) tail with an additional central lobe. (45 kg) Australian lungfish becomes less active
Sex Male/Female The pectoral fins of the coelacanth Sex Male/Female during dry conditions, and can survive
Status Critically endangered are highly mobile, and it uses these Status Not evaluated for months if kept moist by a covering
to maneuver into crevices to reach of damp leaves or mud. It feeds on
FISHES First seen by scientists in 1938, the fishes and other prey. Populations are Unlike other lungfishes, which often frogs, crabs, insect larvae, mollusks,
coelacanth is a classic example of a poorly documented and estimates are live in pools that sometimes dry up, and small fishes, crushing its prey
“living fossil,” because it belongs to a difficult, but susceptibility to capture the Australian lungfish is found in between its strong toothplates.
group that was thought to have died by humans and a restricted habitat permanent bodies of water associated
range have made the coelacanth an with dense vegetation, such as large, broad,
endangered species. deep pools, reservoirs, and slow- heavy body
flowing rivers. A large, freshwater fish
with a heavy body, it has a specialized paddle-
swim bladder that functions as a single shaped,
lung. Although it normally breathes paired fins

long, tapering tail

Latimeria menadoensis it is physically very similar to the Protopterus annectens season, this fish burrows into mud,
coelacanth of southern Africa (see forming a mucus-filled cocoon. It lives
Indonesian above), it almost certainly has a West African lungfish in a variety of freshwater habitats, and
coelacanth comparable way of life. Molecular is carnivorous, capturing its prey by
analysis has shown that the 2 species stealth rather than by rapid pursuit.
Length Up to 51⁄4 ft probably diverged from each other Length 6 – 61⁄2 ft
Location Pacific (1.6 m) between 4.7 and 6.3 million years ago. Location W. to C. Africa (1.8 – 2 m)
(Celebes Sea) Weight 145 – 220 lb Since then, they have been kept apart Weight Up to 37 lb
(65 – 98 kg) by the geology of the seabed, and by (17 kg)
Sex Male/Female currents that confine them to their own Sex Male/Female
Status Vulnerable particular parts of the world. Like its Status Least concern
African counterpart, the Indonesian
The Indonesian coelacanth was coelacanth appears to be a solitary fish The West African lungfish has long,
discovered in the late 1990s, and as in open water, but it has also been found threadlike, paired fins, and is the largest
yet, relatively little is known about its in groups in caves. So far, population of the 4 lungfishes found in Africa. Like
behavior or ecology. However, since estimates are not available, but it is likely the other 3 species, it breathes through
to be endangered. The chief threat to a pair of lungs. At the onset of the dry
this coelacanth’s survival is fishing, which
can have a severe effect on a species
that is geographically highly isolated.

PRIMITIVE RAY-FINNED FISHES 489

Primitive ray-finned fishes

PHYLUM Chordata Among the least advanced of all bony fishes, rows of large, thickened scales (bony studded with sharp teeth, resembling
CLASS Osteichthyes primitive ray-finned fishes have an unusual scutes) protect an otherwise scaleless the snout of a crocodile. Gars are
skeleton composed partly of bone and partly body. Paddlefishes have a long, covered by smooth, thickened ganoid
SUBCLASS Actinopterygii of cartilage. There are 4 groups (orders): paddle-shaped rostrum, which may scales (see p.468).
act as a sensory organ or improve the
ORDERS Polypteriformes, sturgeons and paddlefishes, gars, bichirs, flow of water to the mouth during Bichirs have a long, slender body
Acipenseriformes, and the bowfin (a single species that is placed feeding. These filter-feeding fishes use protected by thick scales. Most
Lepisosteiformes, in a separate order). Primitive ray-finned their gaping mouth and large gill species (sometimes referred to as
Amiiformes chambers to strain small aquatic the true bichirs) have a row of small
organisms from the water. finlets on their back and a pectoral
FAMILIES 5 fishes are among the largest of all freshwater fin divided into fleshy lobes.
SPECIES 49 species, with sturgeons reaching lengths Gars are cylindrical and highly
of 26 ft (8 m). Unique to the Northern predatory fishes that catch prey The bowfin is much smaller than
through ambush or bursts of speed. other primitive ray-finned fishes. A
Hemisphere, most species live in freshwater, although some The elongated rostrum and jaws are predatory fish, it has a blunt head
and small teeth.
are able to live alternately in fresh and saltwater.

Anatomy PADDLEFISHES FISHES

In most primitive ray-finned There are two species of paddlefishes, both found in large river
fishes, the skull and some fin systems with an ample supply of plankton. The American
supports are made of bone, while paddlefish (shown here) lives in the Mississippi river system;
the body and tail are supported by it feeds at night and spends the daylight hours resting at the
a cartilage notochord with some bottom of deep pools. The other species lives in the Yangtze River.
rudimentary vertebrae. The tail is
asymmetrical, with the end of the
notochord extending into an upper lobe
that is longer than the lower one. Gars,
some bichirs, and the bowfin have a
swim bladder lined with blood vessels
that can be used as a lung when levels
of oxygen in the water are low.

Sturgeons are large, bottom-feeding
fishes with a flattened snout, a
protrusible mouth, and sensitive
barbels for locating food. Several

Acipenser sturio Heavily overfished for its flesh and eggs— Polypterus ornatipinnus Lepisosteus osseus
caviar is made of the unshed eggs of
European sturgeon females—the European sturgeon is now Ornate bichir Longnose gar
extremely rare. It used to swim up many
Location Previous known Length Up to 11 ft European rivers to breed, but spawning in Location W. to C. Africa Length 16 in Location C. to E. North Length 4 – 6 ft
range North Atlantic, (3.5 m) the wild is now restricted to the Garonne (40 cm) or more America (1.2 – 1.8 m)
Mediterranean, Europe Weight Up to 690 lb River in France. It is greenish brown and, Weight Up to 18 oz Weight Up to 33 lb
(315 kg) like other sturgeons, has a downward- (500 g) (15 kg)
Sex Male/Female facing mouth. Estimates suggest fewer Sex Male/Female Sex Male/Female
Status Critically endangered than 750 wild fish are left, but this species Status Least concern Status Least concern
is now farmed for stocking into rivers.
flattened 5 rows of bony Bichirs are cigar-shaped fishes with
head scutes along body triangular finlets arranged in a row
down the rear half of their
Polyodon spathula One of the few freshwater fishes that backs. They have armorlike diamond-
feed by straining plankton from water, scales and tubular nostrils, shaped scales
American paddlefish the American paddlefish is often and can breathe atmospheric air since
described as a living plankton net. their swim bladder functions much like The longnose gar is one of a group of
Length 4 – 6 ft It sweeps through the water with its a primitive lung. The ornate bichir—one primitive North American fishes that
(1.2 – 1.8 m) lower jaw dropped and the sides of of 14 species in the bichir family—is have long jaws with sharp teeth. Its
Habit Up to 53 lb the head inflated to form a funnel-like beige, covered by black, netlike body is long, and its propulsive fins are
(24 kg) opening, filtering large amounts of markings. It is a slow swimmer that set far back—much like those of pikes
Sex Male/Female water and extracting plankton with its stalks its prey, such as small fishes, (see p.502). It is primarily a freshwater
Status Vulnerable gills. The underside of its distinctive amphibians, and crustaceans, quickly fish, but in the southern part of its
paddle-shaped snout is covered with sucking them in when in range. range, adults are frequently found in
electrosensitive pores. This fish has been brackish water. The longnose gar hangs
Location C. to S.E. North heavily exploited for its flesh and eggs. motionless in the water, hidden by
America vegetation, and waits for prey to come
bluish gray, scaleless skin within striking distance. Then, with a
sudden thrust, it takes the prey
cross-wise in its mouth, often holding it
for several minutes. Its predatory habits
make it unpopular among fishermen
since it can become entangled in nets
and cause a good deal of damage.

490 BONY FISHES

Bony-tongued fishes

PHYLUM Chordata The bony-tongued fishes are named after fish and the knifefish, can produce and and the freshwater butterflyfish, the
CLASS Osteichthyes the tooth-studded tongue and palate detect electrical signals, which they use swim bladder has a lunglike lining
found in most species. These relatively for navigation and communication. In so that it can be used as a temporary
SUBCLASS Actinopterygii large fishes—up to 9 3⁄4ft (3 m) long—live some species, such as the arapaima lung in oxygen-poor water.
ORDER Osteoglossiformes mainly in freshwater in the tropics. This

FAMILIES 5 group contains such varied forms as the

SPECIES 244 large Amazonian arapaima, the peculiar

elephantnose fish (which has an

extended, downward-curving mouth), the eellike

knifefish, and the delicate and ornate freshwater

butterflyfish. Most are carnivores, feeding

chiefly on invertebrates, but a few species

eat detritus and plant material.

FISHES Anatomy ELECTRIC ELEPHANTNOSE

Although some species also have Elephantnose fishes navigate using
teeth in their jaws, all bony-tongued electrical signals. An electrical field
fishes have many small, sharp teeth is created around the fish’s body by
on both their tongue and the roof of modified muscles, and disturbances
their mouth, which are used to exert in this field are detected by
the main biting motion when seizing receptor cells.
prey. Most species in this group have
a relatively elongated body with
prominent eyes and large, hard
scales, often with fine ornamentation,
although some have reduced scales.
The dorsal and anal fins are usually
placed far back on the body and are
often very long. Some fishes in this
group, particularly the elephantnose

Chitala chitala Pantodon buchholzi Arapaima gigas One of the largest purely freshwater
fishes in the world, the arapaima has
Clown knifefish Freshwater Arapaima a streamlined, gray to dark greenish
butterflyfish yellow body with long dorsal and anal
Length Up to 34 in Length 81⁄4 ft (2.5 m), fins set back close to its tail, a common
(87 cm) Length 4 – 5 in max 15 ft (4.5 m) feature among fishes that make sudden
Weight Not recorded (10 – 13 cm) Weight Up to 440 lb lunges to catch their prey. Apparently
Sex Male/Female Weight Up to 18 oz (200 kg) unable to fulfil its respiratory requirements
Status Near threatened (500 g) Sex Male/Female with its gills alone, it takes in air from
Sex Male/Female Location N. South America Status Data deficient the surface of the water.
Location S. Asia Status Least concern

Location C. Africa light gray-green powerful,
juvenile rounded tail fin
coloration
tiny, featherlike dorsal fin

This fish is a surface-feeding Gnathosomus petersii radar to detect obstacles, food, and
insect-eater, able to leap 31⁄4 ft
With a body flattened from side to side, Elephantnose fish mates. The highly mobile, fingerlike
adult clown knifefishes are conspicuously (1 m) or more out of water to
hump-backed, whereas the young are catch its prey or escape appendage on its chin is used for
relatively slender. The unusually small from predators. In addition
dorsal fin is featherlike, giving rise to probing the muddy bottom in search
this fish’s other common name, to hanging motionless at the
the featherback. This fish surface, it is often seen standing Length Up to 9 in of food. The elephantnose has an
swims equally well forward or for long periods in shallow water, (23 cm)
backward, with an undulating using its pelvic fin rays as stilts. It Weight Up to 21⁄4 lb unusually large brain that, in relation to
motion of its large anal fin—the has a large, lunglike swim bladder, (1 kg)
main propulsive organ. It has a believed to function as an additional Sex Male/Female body mass, is equalled only by that of
swim bladder modified to form air-breathing organ. Status Least concern
an accessory breathing organ, humans. Perhaps for this reason, it has
and frequently rises to the surface dark bands
to obtain air. It is often seen at on all fins a remakable ability to learn, and its
the surface, splashing as it rolls
over, exposing its silvery flanks. pelvic fins with Location W. to C. Africa playful behavior makes it a popular
elongated rays
aquarium fish. constricted
tail base

Commonly found in still, murky, elongated,
muddy waters of rivers, compressed body
lakes, and swamps, this fish
possesses a weak electrical
system that functions as a kind of

TARPONS AND EELS 491

Tarpons and eels

PHYLUM Chordata This group consists of 3 main lines: eels, head that tapers into a tubular body water, after which the adults die. The
CLASS Osteichthyes tarpons, and halosaurs. Although they look and elongated tail. They are covered leptocephalus larvae are carried
and behave differently as adults, they all in small scales and have reduced fins, passively toward coastal waters by
SUBCLASS Actinopterygii start life as a transparent larva (known as a some of which have sharp spines. ocean currents. After about 1 – 3
years, they develop fins, scales, and
SUPERORDER Elopomorpha leptocephalus larva). These leaflike larvae may Breeding and migration pigmentation before beginning their
journey upriver to the areas where
ORDERS 4 drift in ocean currents for several years before The breeding cycles of some eels they grow as adults.
involve remarkable migrations. Most
FAMILIES 24 reaching adulthood. Most eels are marine, but marine eels spawn near where they Hunting and feeding
live, but freshwater eels and some
SPECIES About 1,000 a few live mainly in freshwater and return to marine species have separate Tarpons, halosaurs, and eels are all
spawning grounds, usually far out to predators. The fast-swimming tarpons
the sea to breed. Tarpons are largely confined sea. For example, North American use speed to catch other fishes. Eels
and European eels, both of which live are more likely to ambush their prey,
to coastal areas of the tropics, while halosaurs occur in the deep in freshwater lakes and rivers, travel using rocks or reef crevices for cover.
over 4,000 miles (6,400km) to different Many eels have long, sharp teeth for
sea worldwide, down to depths of at least 6,000ft (1,800m). parts of the Sargasso Sea in the seizing prey; others have thickened
western Atlantic. It is thought that teeth for crushing shells. Some species
Anatomy scaleless, but some species have during this journey, which takes 4 – 7 search the bottom for buried prey or
fine scales embedded in their skin. months, they do not eat. Instead, they scavenge on dead animals. Deep-sea
Eels are elongated and snakelike. The Tarpons look more like large herring survive by consuming stored fat and gulper eels have gigantic mouths and
spinal column consists of more than than eels. Their bodies are deeper muscle tissue. They may also absorb distensible stomachs, and can eat
100 vertebrae, which makes the body and less elongated, with large, reflective nutrients through the lining of their prey much larger than themselves.
very flexible. Long dorsal and anal fins scales, and well-developed and mouth. Spawning occurs in deep Halosaurs feed on invertebrates.
may extend most of the length of the differentiated fins. Halosaurs, however,
body, and the pectoral and tail fins are are more eellike in shape, with a large
often very small or lost entirely. There
are no pelvic fins. Most eels are

FISHES

HUNTING

Eels catch prey in different ways but many ambush prey
rather than chase it, as tarpons do. Moray eels (shown
here) often hide in crevices, from which they launch
surprise attacks when suitable prey is within reach.
However, they also emerge at night and actively hunt their
prey. The wide mouth is armed with sharp teeth, making
it difficult for prey to escape once it has been caught.

492 BONY FISHES

Elops saurus Also known as the ten-pounder, this Albula vulpes a sport fish than as food. Like tarpon,
sleek, blue-gray fish is covered with it can survive in low-oxygen water by
Ladyfish fine scales. It attacks small fishes in Bonefish gulping air. It feeds on a rising tide,
schools, and is well known for its habit working its way to the muddy bottom
Length Up to 31⁄4 ft of skipping along the surface and for Location Atlantic Length 31⁄4 ft with its head down and tail up, blowing
(1 m) leaping when hooked. Adult ladyfishes (Up to 1 m) jets of water to uncover its prey—usually
Weight 31 lb move out from the coast into open Weight 20 lb clams, crabs, and shrimps. Its large
(14 kg) water to spawn in schools; exact (9 kg) size affords it some protection
Sex Male/Female locations are not known, but they Sex Male/Female from predators.
Status Least concern are believed to spawn up to 100 miles Status Near threatened
Location W. Atlantic, Gulf (160 km) offshore. The transparent,
of Mexico, Central eel-like larvae eventually drift or faint vertical conical,
America, Caribbean migrate back to inshore waters. stripes on adults scaleless
head
deeply
blue-grey body forked tail Found in shallow, coastal marine
habitats, typically over mud flats
and mangrove lagoons, the
bonefish is more important as

Anguilla anguilla OUT OF WATER

European eel

Megalops atlanticus found in coastal waters and estuaries, Location E. North Atlantic, Length Up to 31⁄4 ft
and sometimes also in freshwater, and Mediterranean, Europe (1 m)
Tarpon feeds almost exclusively on schooling Weight 10 lb (4.5 kg),
fishes such as sardines, anchovies, max 29 lb (13 kg)
and mullets. Its lunglike swim bladder Sex Male/Female
enables it to overcome the occasional Status Critically endangered
shortages of oxygen that occur in
Location W. and Length 1⁄4 – 81⁄4 ft estuaries and similar kinds of habitat, This eel has a remarkable life history. European eels can survive out
E. Atlantic (41.3 – 2.5 m) by breathing air at the surface. It is Adults are believed to spawn in the area of water for several hours in damp,
Weight 350 lb a popular sport fish, and makes of the Sargasso Sea, the larvae being cool conditions. Adults usually
(160 kg) spectacular leaps when hooked. transported over a period of 21⁄2 years travel overland on rainy nights,
Sex Male/Female Between late April and August, adult to European coastal waters by ocean when the darkness gives them
Status Vulnerable tarpons move into open water to spawn. currents. There, they metamorphose some protection from attack.
The transparent, eellike larvae may be into cylindrical, unpigmented “glass
FISHES transported for a year or more, ultimately eels” before entering rivers in their lance-shaped—changes that are
ending up in estuarine nursery grounds, millions, as silvery, pigmented juveniles adaptations to the ocean’s depths.
A large and powerful fish, with a deep but also frequently occur in pools or called “elvers.” The freshwater stage Once an extremely common fish, the
body and an upturned mouth that lakes disconnected from the sea. is a feeding and growing phase; as European eel has declined dramatically
extends far beyond the eyes, the tarpon the eel matures sexually, it descends in recent decades. Pollution, dams, and
looks like an unusually large herring. It is unusually toward the sea. Mature “silver eels” overfishing are serious threats, together
large eyes undertake their spawning migration with climate change.
long ray at rear usually from late summer to winter and
end of dorsal fin mainly on dark, moonless, stormy ADULT COLORATION single
nights. At this stage, the eyes enlarge, In its freshwater stage, this fish fin
the snout becomes more narrow and has a yellowish or even golden
pointed, and the pectoral fins more underside. As it approaches
sexual maturity, it becomes
cylindrical body silvery below and almost
black above (as shown here).

deeply forked
tail fin

Gymnomuraena zebra showing. They have no pectoral or pelvic size. An aggressive fish, it is known
fins. There are 200 species, and many, to defend its territory strongly against
Zebra moray including the zebra moray, are brightly intruders. Some morays, although
colored. This snakelike fish has a long, not necessarily this species, are
Location Pacific, Gulf of Length Up to 5 ft cylindrical, highly muscular body, and noted for the presence of toxins blunt snout
California, Indian Ocean (1.5 m) a large mouth with blunt and pebblelike on their skin.
Weight 22 lb teeth, adapted for crushing prey. It usually black or brown
(10 kg) adopts a lie-and-wait feeding technique, highly vertical bands
Sex Male/Female and typically lurks in rock or coral muscular body paddlelike tail
Status Not evaluated crevices, lunging outward to catch its
prey. However, it may occasionally leave
its hole at night in search of prey. The scaleless skin
zebra moray feeds on large and heavily
Morays are thick-bodied and often armored prey, particularly crabs and
powerful eels that typically lurk in clefts in other crustaceans, found around reefs.
rocks or coral with only their heads There is evidence that it can eat larger
crabs than other morays of comparable

TARPONS AND EELS 493

Avocettina infans have numerous teeth. It probably feeds Conger conger IN HIDING
exclusively on small crustaceans. Young
Avocet snipe eel male and female avocet snipe eels look Conger eel Like most of its relatives, the
very similar, but as the males approach conger eel hides during the day in
Location Tropical, Length Up to 30 in sexual maturity, they undergo a marked Location E. North Atlantic, Length 83⁄4 ft crevices, emerging at night to chase
subtropical, and temperate (75 cm) transformation. Their jaws become Mediterranean (2.7 m) and ambush prey. Small conger eels
waters worldwide Weight 1 lb drastically shortened, and all their teeth Weight 145 lb are sometimes found in tide pools
(0.5 kg) are lost. At this stage, males and females (65 kg) on rocky shores, as well as in rocky
Sex Male/Female look so different that at one time they Sex Male/Female offshore habitats, while large ones
Status Least concern were classed in separate families. Little Status Least concern often inhabit wrecks of sunken ships.
known, it is usually only captured by
specially designed, deep-sea fishing gear inshore for 1 – 2 years before growing into
during scientific research expeditions. juvenile eels; they reach sexual maturity
at 5 – 15 years.
A deep-sea eel with a brown or slender, fragile, large eyes This dark gray, thick-bodied fish is one of SNAKELIKE FISH
black body, the avocet snipe body nearly 200 species in the conger family. The conger eel, with its snakelike form and
eel belongs to a family of As with most eels, it has no scales. With long snout, can slip into small crevices in
about 9 species. Its jaws whiplike open jaws its large size and well-equipped jaws search of its prey.
cannot be fully closed and tail providing protection from most predators,
it hunts at night for fishes, crustaceans,
Myrichthys colubrinus There are over 300 species of snake and cephalopods. The conger eel is
eels worldwide and they occur in a wide considered an excellent food fish and is
Banded snake eel range of colors and shapes. They are frequently caught by anglers. It can be
mostly less than 31⁄4 ft (1 m) long, and found on rocky and sandy bottoms, at
Length Up to 371⁄4 in burrow in shallow, sandy and muddy depths of up to 1,640 ft (500 m). While
(95 cm) bottoms of lagoons, sandy flats, and juveniles live inshore, adults move
Weight 61⁄2 lb reefs. This species has a hardened, offshore as they grow and mature. The
(3 kg) sharply pointed tail, modified for female conger eel lays between 3 and
Sex Male/Female burrowing tail-first into the sand. 8 million eggs, which hatch to produce
Status Not evaluated Primarily active at night, it feeds on transparent, eellike larvae. These drift
sand-dwelling fishes and crustaceans,
Location Indian Ocean, and seems to detect its prey by smell.
W. Pacific
25 – 32 black
hard, rings on body FISHES
pointed tail

Heteroconger hassi This eel lives in large colonies, with Aldrovandia affinis This relatively rare fish is found hovering
over the bottom in water between
Spotted garden eel the lower half of its body buried in the Halosaur 2,300 and 6,600 ft (700 – 2,000 m) deep.
This species is usually only captured by
sandy seabed. The upper half of its Length Up to 22 in specially designed, deep-sea fishing gear
(55 cm) during scientific research expeditions.
body projects into the water, creating Weight 13 lb Little is known about the halosaur
(6 kg) but its well-developed nasal organs,
Length Up to 14 in “gardens” that sway gracefully with the Sex Male/Female particularly among the males, seems to
(36 cm) Status Least concern indicate that sense of smell is a means
Weight 41⁄2 lb current. When a colony is approached of communication between the sexes.
(2 kg)
Sex Male/Female by a diver, the eels nearest the diver
Status Not evaluated
slowly sink, each into its individual Location Tropical,
subtropical, and temperate
burrow, to hide from the intruder, in waters worldwide

Location Red Sea, perfect gradation from one end of the
Indian Ocean, W. Pacific
“garden” to the other. The
large, anal fin extends
spotted garden eel feeds smooth scales to tip of tail

dark by picking up small well-developed nose
spots organisms, such as tiny
tail used as anchor behind planktonic invertebrates
in burrow head or larval fishes, one by one,

from the water flowing by.

Saccopharynx ampullaceus pelican eel’s). It also has a luminescent Eurypharynx pelecanoides enormous jaws equipped with tiny
organ at the tip of its tail which, if teeth. Its huge gape and expandable
Gulper eel dangled in front of its mouth, may be Pelican eel stomach enable it to swallow and
used to entice prey. It is thought that this digest fishes almost as large as itself.
Location North Atlantic Length Up to 51⁄4 ft fish swims slowly, with its enormous Location Tropical and Length 231⁄2 – 39 in Due to its odd shape and fragile build,
(1.6 m) jaws swung open so that its prey literally subtropical waters (60 – 100 cm) the pelican eel is almost certainly a
Weight 21⁄4 lb swims into its mouth. A little-studied fish, worldwide Weight 21⁄4 lb poor swimmer and may not pursue
(1 kg) the gulper eel belongs to a rare family, (1 kg) other fishes. Instead, it probably relies
Sex Male/Female known from fewer than 100 specimens. Sex Male/Female heavily on the luminescent organ at
Status Least concern Status Not evaluated the tip of the tail to attract prey.
distensible
stomach large jaws

The gulper eel is a relative of This deep-sea fish is one of body tapers to
the pelican eel (see right), with the most unusual of eels, with thin filament
a similar small head and large a thin, tapering body, but
jaws (although smaller than the

494 BONY FISHES

Herrings and relatives

PHYLUM Chordata These small, streamlined fishes are widespread and
CLASS Osteichthyes abundant. Often forming vast schools, they are an
important part of marine food chains and are vital
SUBCLASS Actinopterygii to many coastal economies. The herring family
SUPERORDER Clupeomorpha includes sprats, shads, and pilchards; it

ORDERS 1 (Clupeiformes) also includes sardines, although this

FAMILIES 5 term is often used to refer to the

SPECIES 405 young or adults of other species.

Herrings and anchovies occur

from the tropics to temperate zones, mostly in

coastal marine waters with some in freshwater

streams and lakes.

FISHES Anatomy Feeding

Members of the herring family Almost all herrings
are similar to one another in overall and their relatives
appearance. They have streamlined feed on planktonic
bodies that are flattened from side organisms (mainly
to side, with large scales and crustaceans and their
well-developed fins without any larvae), which they filter
supporting spines. Most are silver out of the water by
with green or blue hues on the back, opening their large
becoming progressively lighter on mouths to expose
their undersides. Anchovies are their gill rakers.
generally longer and thinner than Following the daily
herrings, and have a large mouth with vertical movements
a prominent snout. In both anchovies made by plankton, they
and herrings, the swim bladder is usually feed near the surface
linked to the ear apparatus, which is at night and move to lower
thought to enhance their hearing. At depths during the day.
one time, herrings and their relatives Their feeding habits often
were considered to be related to vary seasonally; herrings
tarpons and eels because of similarities and some other species
between their larvae, but now the cease to feed during the
consensus is that they are sufficiently breeding season. Most
different to form a group of their own. members of this group
feed in dense groups of tens
CONSERVATION of thousands of fishes, thus
attracting predators, including
Herrings have a long history other fishes (such as salmon
of human exploitation. Easy and tuna), seabirds, and
to catch and to preserve, they marine mammals. By
are an important source of food contributing to the diet of
and oil. During the days of sail, so many other species,
catches were relatively stable, herrings and anchovies
but the herring harvest soared form a key element in many
in the first half of the 20th century, marine ecosystems.
with the introduction of powered
fishing vessels. In the 1970s, SCHOOLING
the Atlantic herring population Herring schools are at their largest during
crashed. Some stocks are now the breeding season, which usually falls
sustainable and well-managed, in the warmer months of the year. Each
but others are not. female releases up to 60,000 eggs,
which form a sticky mat on the seabed.

Clupea harengus For centuries, the sleek, silver-scaled techniques, but are now recovering its wide range, the species is divided
herring has been one of the most slowly because of active management. into many local races, which differ from
Atlantic herring important commercially fished species Like most of its relatives, the Atlantic each other in habits and in size. Each
in the North Atlantic. Its numbers herring is a plankton-feeder, and lives in race uses a number of traditional
Length Up to 16 in declined precipitously during the 20th spawning grounds. Young herrings,
(40 cm) century, due to improved fishing large, highly mobile schools. It comes which initially resemble tiny eels, hatch
Weight Up to 25 oz to the surface at night, but spends on the seabed, but soon swim upward
(700 g) dorsal fin in the day in deeper water. Across to feed close to the surface. They are
Sex Male/Female center of body eaten in vast numbers by other fishes,
Status Least concern
Location North Atlantic, and only a tiny proportion of them
North Sea, Baltic Sea survive to become adults.

strongly forked tail heavy lower jaw

HERRINGS AND RELATIVES 495

Sardinops sagax caeruleus Alosa sapidissima distinctive in that it enters rivers to showing. Adults return to the ocean
spawn. Beginning at the age of 4 or 5, after spawning, and the young shad
California pilchard American shad American shad migrate to rivers every hatched out in the river migrate to the
year to spawn. Spawning occurs near oceans in autumn. The numbers of
Location E. North Pacific Length 10 – 14 in Location W. North Length 20 – 231⁄2 in the shore, after sunset, usually in late American shad have suffered because
(25 – 36 cm) Atlantic, E. North America. (50 – 60 cm) summer. Males arrive first, followed by of dam construction and water pollution.
Weight 17 oz Introduced to E. and Weight 41⁄2 lb the females, and pairs swim erratically The Pacific populations of this fish have
(475 g) W. Pacific (2 kg) near the surface with their dorsal fins been introduced.
Sex Male/Female Sex Male/Female
Status Not evaluated Status Least concern dorsal fin in toothless jaws
center of body

This medium-sized silvery fish can With its streamlined silvery body, the
be recognized by its distinctive black American shad looks like many other
spots, arranged in rows along its body. fishes in the herring order but it is
In California, it is canned and marketed
as the sardine, and is also extensively Engraulis ringens CONSERVATION Engraulis mordax
used to produce oil and fish meal.
At one time, schools consisting of an Peruvian anchoveta Despite its small size, the Peruvian Californian anchovy
estimated 10 million individuals were anchoveta is one of the world’s
found. During the 1930s, over half Length Up to 8 in most commercially valuable fishes, Length Up to 10 in
a million tons a year were caught, (20 cm) with many millions of tons caught (25 cm)
but stocks dwindled during the 1950s, Weight 7⁄8 oz each year. However, its population Weight 13⁄4 – 21⁄8 oz
and collapsed completely around 1967. (25 g) is prone to sudden crashes, (50 – 60 g)
Today, the numbers of California Sex Male/Female triggered both by El Niño—a Sex Male/Female
pilchard are recovering, but stocks Status Least concern periodic temperature rise in the Status Least concern
are still far from their original levels. East Pacific—and by overfishing.
There have been major crashes in
Location E. South Pacific most recent decades, with severe Location E. North Pacific
repercussions for local people and
Denticeps clupeoides Like its close relative the Californian marine wildlife. This small but abundant fish is important
anchovy (see right), this small, silvery fish commercially and a vital link in the
Denticle herring feeds on plankton, and forms enormous marine chain, providing food for other
schools where upwelling currents create fishes and fish-eating birds. Slender,
Length 31⁄4 in a good supply of food. Following the with a distinctly pointed snout, it swims FISHES
(8 cm) plankton as they migrate, they descend with its mouth open, filtering plankton
Weight Not recorded to depths of about 165 ft (50 m) during from the water with its gill rakers. The
Sex Male/Female the day and rise to the surface at night. Californian anchovy is one of about
Status Vulnerable Peruvian anchovetas also school in huge 150 species in the anchovy family, many
numbers for safety. This fish spawns of which are poorly known and difficult
Location W. Africa largely from winter to early spring. to tell apart. Anchovies are found in all
the oceans of the world.
This small, silver-colored fish is the SLIM FISH
most primitive member of the herring This slender fish, with a pointed snout and
group, being virtually indistinguishable deeply forked tail, has a marked resemblance
from fossil forms. Modified scales along to the Californian anchovy. It swims with an
the underside form backward-pointing open mouth, filter feeding with the help
serrations, and toothlike denticles cover of its fine gill rakers.
the head. It also has a large anal fin.
Unlike most herrings, it lives in
fast-flowing, freshwater. It is also
the only herring to have a complete
lateral line (see p.486) running along
its sides. This fish is omnivorous.

Pristigaster cayana underside has a line of modified Chirocentrus dorab There are two species of wolf-herring,
scales—or scutes—which have sharp, placed in their own family. It has an
Amazon hatchet backward-facing points. Amazon Dorab wolf-herring elongated, bright blue body and
herring hatchet herrings tend to remain in numerous teeth, with 2 fanglike canines
schools for safety and are omnivorous, Length 31⁄4 ft protruding outward from its upper jaw.
Length 53⁄4 in filtering plankton from the water Location Indo-Pacific (1 m) Unlike most herrings, it actively hunts
(14.5 cm) through their gill rakers. They inhabit Weight 14 oz other fishes. Little is known about the
Weight Not recorded the Amazon river basin as far west (400 g) behavior of this species, but the fact
Sex Male/Female as Peru and Colombia. They are also Sex Male/Female that it is a large carnivore strongly
Status Not evaluated believed to enter the slightly saline Status Not evaluated suggests that it hunts alone or in small
waters of the river mouth, but this is groups, rather than in large schools.
Location N. South not well documented. Along with the closely related whitefin
America wolf-herring, it is extensively fished in
some parts of the world.

bright blue
upper body

This thin, freshwater fish abruptly
has a distinctive profile, tapering body
with a deeply curving
belly. Like many members
of the herring family, its

496 BONY FISHES

Catfishes and relatives

PHYLUM Chordata Catfishes and their relatives account for in several groups the scales have of this group that do not have
CLASS Osteichthyes three-quarters of all species of freshwater developed into a dense armor. Nearly a Weberian apparatus. Instead,
fishes. Although they are a varied group, all species have sharp or serrated vibrations are transmitted from the
SUBCLASS Actinopterygii almost all species have a bony internal pectoral and dorsal spines, some of swim bladder to the inner ear by
SUPERORDER Ostariophysi structure, known as the Weberian apparatus, which can release venom. a modified set of ribs.
which is used in sound reception and
ORDERS 5 contributes to their acute hearing. They Characins and cyprinids look similar Feeding
FAMILIES 85 are divided into 5 groups: milkfishes and to one another, although most
SPECIES About 10,500 characins are small and often brightly This group includes voracious
colored, while cyprinids are generally predators, scavengers, herbivores,
relatives, cyprinids (the most widespread dull-colored and can reach lengths and filter feeders. Catfishes are
of up to 6 1⁄2 ft (2 m). Another generally predators or scavengers,
of which are carp and minnows), characins (including tetras, distinguishing factor is the living close to the bottom in murky
arrangement of the teeth: characins water, although a few species are
tigerfishes, and piranhas), neotropical knifefish, and catfishes have teeth in their jaws, often with a herbivores. Most characins are
replacement row directly behind the schooling fishes that eat plants or prey
themselves. Although mostly confined to freshwater, some functional teeth, whereas cyprinids on invertebrates or fishes: piranhas
have toothless jaws but usually have are notorious meat-eaters. Most
species are found in brackish water or the sea. teeth in the pharynx. Characins, unlike species of cyprinids have downward-
cyprinids, also have a small fin (called turned, often suckerlike mouths, with
Anatomy whiskerlike sensory barbels; an adipose fin) between the dorsal fin one or more pairs of sensory barbels
these are used for touch and and tail, which is not supported by on either side. They usually feed on
Catfishes and their relatives vary taste, and they compensate detritus or on small invertebrates
greatly in size and shape. Most are for poor eyesight. Most rays and stores fat. and plants in the sediment; few are
small fishes, less than 4 in (10 cm) species have smooth, Milkfishes and their predatory. Milkfishes are filter feeders
long, although some species reach scaleless skin but relatives (which include but some of their relatives feed on
16 ft (5 m). The Weberian apparatus the beaked salmon) are small animals.
that unites most members of this the only members
group consists of modified vertebrae
FISHES that act as a set of levers to transmit
sound waves received by the swim
bladder to the inner ear. This feature
gives catfishes and their relatives an
acute sense of hearing, and many
species use sound to communicate
with each other.

Catfishes typically have
a flattened head with
a wide mouth that is
usually surrounded by

NIGHT HUNTER

Most catfishes are active at night and feed alone. The
barbels around the mouth are covered with taste buds,
which help them find food. This long-whiskered
(or pimelodid) catfish is found in tropical rivers in
South America. The larger members of this group
feed on fishes and other animals, including monkeys
that fall into the water.

CATFISHES AND RELATIVES 497

Chanos chanos Large and fast-moving, the milkfish Rhodeus amarus Brachydanio rerio
has a streamlined silvery body and an
Milkfish unusually large, deeply forked tail. It Bitterling Zebrafish
can tolerate a wide range of salinity
Length Up to 6 ft but spends most of its life in the sea, Length Up to 41⁄4 in Length Up to 21⁄4 in
(1.8 m) swimming up to 19 miles (30 km) (11 cm) (6 cm)
offshore to spawn. The larvae and Weight Not recorded Weight Not recorded
Weight Up to 31 lb juveniles develop in warm, coastal Sex Male/Female Sex Male/Female
(14 kg) wetlands, in brackish and freshwater Status Least concern Status Least concern
environments. Milkfish larvae are
Sex Male/Female collected and cultured in ponds for food
in Southeast Asia and the west Pacific;
Location E. Pacific, Status Not evaluated adults are also prized as food fish. Location C. and E. Europe Location S. Asia

North and South America, is well camouflaged, and its eyes are
Indo-Pacific, Asia, Australia protected from abrasion by a thin
covering of skin. It has silvery flanks,
and the tips of its anal and tail fins are This fish lives mostly in overgrown elongated 4 dark, lateral
tinged with orange or pink. Its dorsal waterways with minimal water body stripes
fin is set far back on the body. The flow. The females are silvery, but
Gonorhynchus gonorhynchus beaked sandfish is found on during the breeding season the Also known as the zebra danio, this
sandy shores across the males become an iridescent highly active, freshwater fish has a
Beaked sandfish Southern Hemisphere, at silvery blue. Bitterlings have an slender, silvery yellow body, with
depths of up to 660 ft (200 m). unusual way of reproducing: using a characteristic pattern of 4 horizontal
Length Up to 231⁄2 in It feeds on invertebrates that a long egg-tube, or ovipositor, the stripes running from its head to the
(60 cm) live on the seabed, and its female lays her eggs in the mantle cavity tip of its tail. This tiny fish feeds on
Weight Not recorded small, downward-pointing mouth lacks freshwater invertebrates, including
Sex Male/Female teeth and is surrounded by small of a freshwater mussel, over which worms, insect larvae, and crustaceans.
Status Not evaluated sensory flaps, or papillae, that help the male sheds his sperm. The The female is slightly larger than the
it find food. This fish is also called a young grow in this “living nursery,” male, and breeds by scattering her
beaked salmon but this is misleading without harming their host. eggs in open water, or on the bottom
because it is not a true salmon. of ponds and pools. Zebrafishes are
deep body widely used as a model organism in
ORNAMENTAL CARP small developmental biology. Several varieties
head of this popular aquarium fish have been
Selective breeding has created created by breeders.
Location S.E. Atlantic, different varieties of common carp FISHES
Indian Ocean, Pacific over the centuries. Mirror carp have
Ocean large scales, while leather carp
have no scales at all. Leather carp
This fish is adapted for life on the are raised for food; the multicolored Myxocyprinus asiaticus is triangular in cross section, with
seabed, where it spends most of variety shown here is kept as an a pointed back, or hump, and a flat
the daytime hiding in sand or mud, ornamental fish. Chinese sucker underside. It faces upstream to feed,
emerging at night to feed. Its upperside so that the current pushes it against the
TOOTHLESS JAWS riverbed—an adaptation that prevents
Cyprinus carpio The jaws of the common carp Length Up to 231⁄2 in it from being swept away.
have no teeth. It grinds food with (60 cm)
Common carp Weight Not recorded dark
the pharyngeal teeth at the Sex Male/Female bands
back of the throat. Status Not evaluated

Length Up to 4 ft Location China silver to orange
(1.2 m) coloration
Weight Up to 82 lb
Location W. Europe to (37 kg) This slow-moving, hump-
S.E. Asia Sex Male/Female backed fish is one of the few
Status Vulnerable Asian species in the sucker
family. It has protrusible, fleshy
lips, which it uses to collect small
animals from the riverbed mud. Its body

Originally from Europe and Asia, this Chromobotia macracanthus loaches—including this one—can
deep-bodied, freshwater fish has been defend themselves by raising a sharp
raised in semicaptivity for centuries, Clown loach spine in front of each eye. They use
and introduced to rivers, lakes, and these spines against potential
ponds in many parts of the world. Length Up to 12 in predators, and sometimes against
It uses its protrusible mouth to grub (30 cm) each other. The clown loach spawns
through the bottom sediment for Weight Up to 17 oz in fast-flowing rivers,
plant and animal food. (470 g) at the onset of the
Sex Male/Female rainy season.
protrusible Status Not evaluated
mouth

Location S.E. Asia

A popular aquarium fish, the clown mustachelike 3 broad, wedge-
loach is a bottom feeder, feeling for barbels shaped black bands
aquatic invertebrates with the 4 pairs
of barbels that hang down like a
mustache from its mouth. Many

498 BONY FISHES

Gyrinocheilus aymonieri Found on solid surfaces at the bottom Copella arnoldi Hydrocynus vittatus
of flowing water, this slender fish has
Siamese algae-eater a modified mouth and lips that it uses Splash tetra Tigerfish
to attach itself to rocks and plants,
Length 11 in scraping plant material from them. Length 12⁄4 in Length 31⁄4 ft
(28 cm) It is golden green above and silvery (4 cm) (1 m)
Weight Not recorded below, and has a large dorsal fin with Weight Not recorded Weight 40 lb
Sex Male/Female 9 branched fin rays. The Siamese Sex Male/Female (Up to 18 kg)
Status Least concern algae-eater is commercially exploited Status Not evaluated Sex Male/Female
for food and the aquarium trade. Status Least concern
Location S.E. Asia Location N. South Location Africa
dark spots or stripe America
along sides

dark blotch on This African fish is a fierce, freshwater
female
smaller, lighter predator, and a well-known gamefish,
fins of female
prized for its habit of fighting back when

hooked. It has a sleek silvery

body, marked with dark

horizontal stripes, a deeply

forked tail edged with black, and

Anostomus anostomus body, from the snout to the tail fin. The Also called the jumping characin, this large, fanglike teeth. Tigerfishes move in
slender head has an upturned snout, finger-sized fish has a slender, creamy
Striped headstander and all fins have reddish bases. This yellow body, with a black stripe on the schools while feeding, and swallow their
fish gets its name from its habit of head and through the eye. It belongs
swimming head-down, at an oblique to a group of freshwater species, the prey whole, head first. They can eat
angle to the beds of rivers and streams. lebiasinids (pencilfish), often kept in
It swims in small schools (containing aquariums. This particular species gets fishes up to half their length. Apart from
up to 40 individuals), often remaining its name from its distinctive reproductive
Length 61⁄2 in motionless among vegetation. Its behavior. The female lays her eggs on humans, the African fish eagle is their
(16 cm) upturned mouth enables it to feed the underside of overhanging leaves,
Weight Not recorded from leaves and stems. so that when the water level drops, they only significant enemy. The giant
Sex Male/Female are safe from most predators. The male
Status Not evaluated then splashes them with water to keep tigerfish (Hydrocynus goliath), a relative
them alive and the young fishes
of this species and also from Africa, is
drop back into the water
after they have hatched. one of the largest characins, growing up
Splash tetras feed on worms,
Location N. South to 6 ft (1.8 m) dark spot on
America insect larvae, and crustaceans. long. top of second
large eyes dorsal fin
reddish base
3 dark stripes of fins
along body

FISHES This slender, torpedo-shaped pelvic fin directly
fish is golden yellow, with below dorsal
3 broad, black horizontal
bands running along the

Astyanax mexicanus Found in springs, creeks, and small using its pressure-sensing lateral in color and eye development, the
rivers, the Mexican tetra typically has line and its keen sense of smell. 2 forms of Mexican tetra are similar at
Mexican tetra a silvery body with red and yellow fins. Despite the differences a genetic level, and can interbreed.
This fish is of interest to biologists
Length 43⁄4 in because a variant of the species is reduced pigmentation
(12 cm) found in caves. The
Weight Not recorded subterranean form, called
Sex Male/Female blind cave characin
Status Least concern (pictured right), looks
very different, with its
Location S. Central USA to reduced pigmentation
Mexico and nonfunctioning eyes
covered by skin. Like other
cave-dwelling fishes, it finds food by

Pygocentrus nattereri than themselves, such as insects, kill animals as large as capybaras and SLICING TEETH
aquatic invertebrates, or other fishes, horses, and have also resulted in some
Red piranha and will also feed on seeds and human deaths. During the breeding Red piranhas have small but
fruit. However, given an opportunity, season, female red piranhas lay up to sharp, triangular teeth set
Location N., C., and Length Up to 20 in these extremely aggressive, voracious 1,000 relatively large eggs, and attach in powerful jaws. The teeth
E. South America (50 cm) predators can kill much larger prey by them to the roots of trees trailing in the interlock when the fish’s
Weight Up to 83⁄4 lb hunting as a group, feeding in a frenzied water. Both parents, particularly the mouth is closed, enabling
(3.9 kg) rush reminiscent of the behavior of male, guard the eggs until they hatch, it to slice off chunks of flesh.
Sex Male/Female some sharks. These mass attacks can which takes about 9 – 10 days. The blunt snout and
Status Not evaluated underslung lower jaw also
RED BELLY thick fins help it to attack, allowing
The red piranha is it to bite with unusual force.
usually silvery, with numerous
silvery red-flecked body spots
eyes, and a head
Notorious for its predatory, pack- that is dark gray
feeding behavior, the red piranha above and
is extremely variable in appearance, orange-red
displaying a wide diversity of color below. In large
and shape in different parts of its range. individuals, the
Red piranhas typically feed at dawn and underside is often
dusk, lurking and then dashing at their intensely red—giving
prey. They generally eat animals smaller this fish its name.