DK Findout! Sharks - DK

Sharks

Author and consultant: Sarah Fowler, OBE

Editor Olivia Stanford Contents
US editor Rebecca Warren
Senior art editor Katie Knutton 4 What is a shark?
Design assistant Rhea Gaughan 6 How big?
Jacket co-ordinator Francesca Young 8 Prehistoric sharks
Jacket designer Amy Keast 10 Shark relatives
Managing editor Laura Gilbert 12 Shark detective
Managing art editor Diane Peyton Jones 14 Cow and frilled sharks
Pre-production producer Dragana Puvacic 16 Dogfish
Producer Srijana Gurung 18 Sawsharks and Bramble sharks
Art director Martin Wilson 20 Angelsharks and Bullhead

Publisher Sarah Larter sharks
Publishing director Sophie Mitchell 22 Mackerel sharks

Educational consultant Jacqueline Harris Great white shark

First American Edition, 2017
Published in the United States by DK Publishing
345 Hudson Street, New York, New York 10014

Copyright © 2017 Dorling Kindersley Limited
DK, a Division of Penguin Random House LLC

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of the copyright owner. Published in Great Britain by Dorling Kindersley
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ISBN 978-1-4654-5751-6

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SEE ALL THERE IS TO KNOW

www.dk.com

The scale boxes » Scale
throughout the book
show you how big a shark
is compared to a diver
who is 6 ft (1.8 m) tall
from head to heel.

2

24 Carpetsharks 46 Sensing electricity
26 Ground sharks 48 Where do sharks live?
28 Skeleton 50 Migration
30 Inside a shark 52 Interview with...
32 Shark eggs 54 Sharks in danger
34 Baby sharks 56 Shark facts and figures
36 Social sharks 58 Top sharks
38 Dinnertime 60 Glossary
40 Hunting 62 Index
42 Filter feeders 64 Acknowledgments
44 Senses
Prickly dogfish Great hamm erhead
Whale shark Frilled shark

Horn shark

Tail ! WOW! Eggs

A shark’s tail shape There are more All sharks produce eggs, but
tells us how well it than 500 different only 40 percent actually
can swim. Crescent- lay them! Most sharks
shaped tails belong types of shark. keep their eggs inside
to the fastest sharks. their body and give
Floppy, rounded tails thresher shark birth to live young.
make for slower, Pelagic This egg has curly
sluggish swimmers. Tig tendrils that wind
Thresher sharks use around seaweed
their long tail to or sea fans so
stun prey. it doesn’t
wash away.

Smallspotted
catshark egg

What is er shark
a shark?
Body
Sharks are fish, but unlike most other
kinds of fish they have a flexible A shark’s muscles are attached to the
skeleton made of a material called inside of its skin. Outside, the skin is
cartilage instead of bone. They have armored with tiny plates, called
gills behind their head to breathe and denticles, that streamline the body.
their strong tail powers them forward. Many sharks have patterned or
Two pectoral fins keep them stable colorful skin, such as the tiger shark.
in the water as they swim around
searching for food to eat. All sharks
are meat-eaters!

4

Blacktip reef shark Dorsal fin

Most sharks have two dorsal Head
fins on their back. These fins
help to stabilize a shark when Many of a shark’s sense
it swims. Their shape and color organs are on its head. As
can be used to identify the type well as the eyes, ears, and
of shark—it’s easy to spot a nose, it has special organs
blacktip reef shark! that detect electricity.
Hammerheads have more
ed hammerhead of these organs than any
Scallop other shark.

Australian angelshark Pectoral fins

Like flaps on an airplane wing, the pectoral 5
fins on a shark’s sides help to steer it and
prevent it from rolling over! Sharks that
live on the seabed, such as angelsharks,
also use their strong pectorals for
swimming or walking.

How big? Basking shark

Not many people realize, but big The world’s second-biggest fish
sharks are fairly unusual. Most shark can grow up to 33 ft (10 m) long.
species are less than 3 ft (1 m) long, The basking shark often swims
and the tiniest of all are under 12 in near the surface, which is where
(30 cm). Large sharks hunt big prey, it gets its name. However, it
but the most enormous sharks of isn’t warming itself in the sun,
all are filter feeders. They eat tiny but feeding on plankton there.
sea creatures called plankton.
Plankton may be small, but filter
feeders eat a lot of it!

Tiny sharks

Some adult sharks are so
small they could fit into
your hand! The biggest
pygmy shark ever seen
was 11 in (27 cm) long.
Their young are really
tiny, only 2–4 in (6–10 cm)
long. Each mom has
eight baby sharks.

! WOW! These sharks
are compared
Many adult in size to an
sharks grow less adult human
than 0.4 in (1 cm) measuring
6 ft (1.8 m) tall.
a year, taking
decades to reach

full size!

6

Whale shark

The whale shark can grow to at least
41 ft (12.6 m) long, and perhaps to
59 ft (18 m). This makes it the
largest fish in the world. It lives in
warm waters, feeding on plankton
and small fish.

Great hammerhead Great white shark

The great hammerhead is The great white shark is
the biggest hammerhead a fierce predator. At 20 ft
shark of all. It can grow (6 m) long, it is big and
up to 20 ft (6 m) long. fast enough to hunt marine
It is quite a rare shark mammals, such as seals
and usually lives alone. and dolphins. However,
Its babies are about its young eat fish until
24 in (60 cm) long. they grow up.

7

Prehistoric sharks

The oldest whole-shark fossil is about 409 million
years old—that’s almost 200 million years older than
the first dinosaurs! A shark’s soft skeleton doesn’t
fossilize easily, but their teeth, fin spines, and scales
are almost indestructible. These provide many clues
about the peculiar, prehistoric sharks below.

Cladoselache

(clay-doe-SAY-lak-ee)
There are many complete fossils of this
medium-sized shark. Some of them even
include the shark’s last meal! Cladoselache
lived in the oceans about
370 million years ago.

We only know about
Helicoprion from its
strange, spiraling
lower teeth.

Helicoprion

(he-LICK-oh-pry-on)
Modern sharks’ teeth drop out all the time, but
Helicoprion grew bigger teeth on top of its old
ones. Spiraling teeth on the lower jaw probably
cut against flat teeth on the upper jaw.
8

Megalodon

(MEGA-low-don)
The only parts of this gigantic predator that have been
found are its huge fossil teeth, so we don’t know what
it looked like. It probably grew to 66 ft (20 m) long,
almost twice as long as a Tyrannosaurus rex,
and ate small whales.

Stethacanthus These teeth
cut huge
(steh-tha-CAN-thuss) chunks from
Male Stethacanthus had some large prey.
unusual features. They had
large, spiny denticles on their We don’t know
nose and on their odd dorsal what the flat-
fin, as well as long “whips” on topped dorsal
their pectoral fins. fin was for!

Hybodus had Hybodus
knife-shaped
dorsal-fin spines. (high-BO-duss)
Hybodus had sharp teeth for
catching slippery prey, as well as
flat teeth for crunching up shellfish.
Its dorsal-fin spines provided
defense against larger predators.

9

Shark ELECTRIC RAYS
relatives
MARBLED ELECTRIC RAY
Sharks aren’t the only fish with Tct“bauohobreseneagettcridtrtveohiegeatueroglinanseesdspasrt”,ewuosofdnhwlanaoltbeploeocrbrakfwekyucidnnelhbaogdeotsclosiewdkdurcyhseort.porouoirflctfeiespst.elhhTre—eehocyectbt,rkyhiow!caedPhrryaaaeicibycrahseiallsdintoy
skeletons made of cartilage. They
have many close relatives: the CHIMAERAS
rays, including skates and sawfish,
and chimaeras. A few rays look
rather sharklike, such as the
saw-nosed sawfish, but most
appear quite different, with flat
bodies and “wings.”

STINGRAYS

SPOTTED EAGLE RAY SPOTTED RATFISH
Shfrtoaawainrvttahgyedtpereeoarefrnyestosehnafhasonsenardt.vitlTneaewhgyaaoeitrnaywssgyhtghiteeniihvplggleaflgiiitnskbslhge.iirv.Ettseahapgiiilntnloteehtlrrsaioav,tpyuemsispceaaaudryleps skliapaTninlrihsngddoeeeesrk-eeiahnnpraeoefrwarwepodaanrnetobetdatoroes,fuficbgsttthuheh5todei0nysibrottasydyuqhpoauamerravsskaareosiylnu.ffsTomicenhmhes.ei.omytShuolaiesvmesereea,

10

GUITARFISH ! WOW!

ATLANTIC GUITARFISH The giant manta ray
afagsTorbtuherrooiepatvnsarreeoerg-.yu,rsTashnbhhyaduesapyr5rhieke0uadldsivskeoepbeuteeathtcnalteiirieenlii,raasewtpnohwgohf htiuigncheluhtaeneirtgsdashaiervennfeeaiodsnsdsh. teTf.ahrhotneoemdmrdeaiag can be 30 ft (9 m)

SKATES wide from
wingtip to wingtip.

SAWFISH

THORNBACK SKATE LARGETOOTH SAWFISH
Thofewihafngaevssgstersnheinfeeiaangadtritreanuetgocrphavtseosaepeeinril,nns2awedt0hbsh.0,Taeitckhnahhiecnerhyamdyylsahaasfoy,yataefvbenrseaekdtcthafihointeneuyosb.ntfdTaedthobaherdyesyairl rUrwgoSanihsarletflarsormpaarh,etn-iuswdddtndialloailetkftetnteeureluraycnn,nofstlduaahtsrepteitrcsaiirthntllhtyarocaerupokyirrrs,tiohhboateeusreadeitctdywtene,xsoitdththshr.oeeetspsmh,escee. ailrylled
fish has hatched.
11

gArnosuwpearntihnedqivuideustailosnhsartko fbienldonogusttwoh. ich Bramble
sharks
Shark
detective Go to page 18 to bump into
these prickly, deepwater sharks.
Sharks don’t all look the same. Scientists
Prickly shark

use sharks’ physical features to divide
them into different groups. In total
Spine o
there are nine groups, or orders, of YES

shark. Answer these questions to Does it have two
small dorsal fins and
sort any type of shark into its NO thorny skin? NO
correct order.

START HERE Does it have a Does it have
small fin near spines on
Does it have more the base of its dorsal fins?
than five gill slits and its tail?
only one dorsal fin on NO
its back?
YES
NO

YESn dorsal fin

Cow and slits Bullhead
frilled sharks YES sharks

Go to page 14 to learn Seven gill Go to page 20 to learn
about the world's most more about the sharks

ancient sharks. with eyebrows.

Broadnose
sevengill shark

Port Jackson shark

12

Angelsharks Sawsharks

Go to page 20 to find Go to page 18 to discover
out about these these living fossils.
raylike sharks.
Longnose sawshark Dogfish
Japanese angelshark
Go to page 16 to discover
some of the world's biggest,

and smallest, sharks.

YES
YES

Is it flat-bodied Does it

with a mouth NO have a long NO Common
at the end of saw-shaped spiny dogfish
Ground
its head? nose? sharks rd eyelid

Is its mouth in front of YES Go to page 26 to Thi
its eyes, which have NO investigate the order
three eyelids each? with the most sharks.

NO

Is its mouth small Tiger shark
and far in front of
its eyes?

YES Mackerel
sharks
Carpetsharks
Go to page 22 to find out about
Go to page 24 to catch sight these magnificent sea creatures.
of the most colorful sharks.

Whale shark

Pelagic
thresher shark

13

This shark has Frilled shark
a long, flexible
body that This mysterious, brown, eellike shark
finishes in lives in the deep sea and is rarely seen.
a long tail. However, the frilled shark is instantly
recognizable because of its snakelike
FACT FILE head and large mouth filled with
needle-sharp teeth.
» Depth: 66–4,920 ft
Dorsal fin
(20–1,500 m) The single,
tiny dorsal fin
» Length: 7 ft (2 m) is located far
» Fun fact: Pregnant females back, next to
the shark’s tail.
produce extra eggs to feed the
long, snaky pups wriggling » Scale
inside their tummy.

Cow and Sense organs
frilled sharks running along its
side help the frilled
shark to locate prey
in the dark.

These two families of fish make up the oldest, most
primitive order of sharks. There are only two frilled shark
species and four cow shark species. They all have six or
seven gill slits instead of the usual five, and only one dorsal
fin. These sharks like cold water and most live in the deep
ocean, but sometimes they journey into cool coastal seas.

14

! WOW! Frilled gill slits
This shark gets its name from its
These are living frilly gill slits. The sixth and longest
fossils—the most pair are connected to each other
primitive sharks underneath its throat.

known.

Large, green
eyes suggest
a life spent
in the deep,
dark ocean.

Teeth
No other shark has
three-spined teeth like
these—perfect for
catching slippery squid
and deep-sea fish.

Broadnose sevengill shark Seven gill FACT FILE
slits help to
This wide-mouthed, spotty shark is the identify this » Depth: 0–165 ft (0–50 m)
only cow shark that lives permanently in shark. » Length: 10 ft (3 m)
shallow water. It is sociable and curious, » Fun fact: This shark has been seen
which makes it popular with divers by
day. At night, it hunts in packs. “spy-hopping”—poking its head
above water to see what’s going on.
» Scale

15

Dogfish

The 130 kinds of dogfish shark are scattered throughout the
world’s oceans. Some live in shallow seas or estuaries, where

rivers run into the sea. Others live in the deep ocean. This group
includes the only sharks that live under polar ice sheets, but
many more can only survive in the warm tropics.

Common The spine on the second
spiny dogfish dorsal fin is longer
than the first spine.
This widespread dogfish
used to be the most common The backbone runs all the
shark in the North Atlantic way into the upper tail.
Ocean. However, it is slow to
reproduce and there are now fewer
of them due to overfishing.

Slendertail lanternshark Huge, green FACT FILE
eyes make it
The dark patches on the tummy of this shark contain possible to see » Depth: 655–2,300 ft
organs, called photophores, that glow in the dark. in the deep,
Its lights may be for signaling to other lanternsharks. dark ocean. (200–700 m)

» Scale » Length: 18 in (46 cm)
» Fun fact: There are

more than 50 species of
lanternshark, including
the smallest shark in
the world.

Greenland shark This giant shark is FACT FILE
This shark lives in Arctic the third biggest
waters where temperatures in the world. » Depth: 0–8,860 ft
average 36oF (2oC). It looks
so dopey that it’s also called (0–2,700 m)
a sleeper shark. A type
of crustacean called a » Scale » Length: 24 ft (7.3 m)
» Fun fact: The meat of
copepod often lives on the
the Greenland shark is
poisonous to eat.

Greenland shark’s eye.

16

Each dorsal fin has a ! WOW! FACT FILE
venomous spine. The
spines have growth Pups are » Depth: 0–1,970 ft (0–600 m)
rings, like trees, and born at different » Length: 7 ft (2 m)
can be used to tell a » Fun fact: The longest spiny
dogfish’s age. lengths—the
biggest moms dogfish journey measured was
have the largest 995 miles (1,600 km).

babies.

» Scale A black eye
suggests
that this is a
shallow-water
shark.

Prickly dogfish The dorsal fins are FACT FILE
very large and look
This is one of five species of deepwater like sails. » Depth: 165–3,280 ft
“rough shark.” The name refers to
the large, sharpened denticles (50–1,000 m)
that cover their skin.
» Length: 35 in (90 cm)
» Scale » Fun fact: These sharks

aren’t good swimmers.
They rely on their oil-filled
liver to help them float.

Birdbeak dogfish The very long, flat FACT FILE
snout has lots of
The skin of this deepwater shark is armored by sense organs for » Depth: 230–4,920 ft
large, pitchfork-shaped denticles along its sides, finding prey in
and it has spines on both dorsal fins. The birdbeak the dark. (70–1,500 m)
dogfish is a type of gulper shark.
» Length: 4 ft (1.1 m)
» Scale » Fun fact: These sharks

sometimes school in large
groups, perhaps to hunt.

17

Sawsharks

These odd-looking, little sharks are unmistakable
because of their long, flat, sawlike snout. They
look similar to sawfish, but the “teeth” along a
sawshark’s snout are thinner and sharper, and
their gill slits are above their pectoral fins. There
are eight types of sawshark.

FACT FILE Longnose sawshark » Scale

» Depth: 130–2,070 ft This southern Australian
sawshark feeds in schools.
(40–630 m) Females give birth to litters of
pups every other winter. Young
» Length: 5 ft (1.5 m) sawsharks can be identified by
» Fun fact: Its long teeth the two or three small teeth
between each large one.
lie flat against its snout
until a sawshark pup
is born.

Thorny skin
The prickly shark’s thin
skin is protected by
regularly spaced denticles.
Each denticle is about
0.2 in (4 mm) across with
a sharp central spine and
scalloped edges.

18

Saw-nosed
A sawshark’s snout, called
a rostrum, detects
vibrations and electric
fields. It may be used for
hunting and defense. The
pair of long barbels smell
and feel around for food.

Bramble sharks

There are only two species of these heavily
armored, sluggish, deepwater sharks. Their
fragile skin is protected by large thornlike
scales, called denticles. When they open their
huge mouth it creates a powerful suction,
which pulls in unwary fish that stray too close.

Prickly shark FACT FILE

This shark is most common in the » Depth: 13–3,610 ft
deep ocean, but sometimes it swims
(4–1,100 m)
along underwater canyons into very » Scale
» Length: 15 ft (4.5 m)
shallow water, close to the shore. » Fun fact: This shark is
The prickly shark has been seen
alone and in small groups. curious when it meets
divers, but it’s not
dangerous.

19

Angelsharks FACT FILE

These wide, flat sharks live in cold water. » Depth: 0–425 ft (0–130 m)
Angelsharks prefer habitats with sand or » Length: 5 ft (1.5m)
mud, as they like to bury themselves to » Fun fact: Angelsharks used to
hide. They lurk in ambush, waiting for
passing crabs and fish, and then snap be called “monkfish” because,
them up with their huge mouth. from above, they look
like a hooded,
robed monk.

Australian angelshark You can tell that an
angelshark isn’t a
This shark is nocturnal, which ray because its pectoral
means it is active at night. fins aren’t attached
During the day it lies buried to its head.
in the seabed. It prefers areas
near seagrass beds and rocks.

Bullhead sharks

There are bullhead shark fossils older than the The horn shark
first dinosaurs! These ancient sharks have big has skin that feels
heads with large snouts, and crests above their rough to the
eyes. Bullhead sharks live in warm water, often touch.
sleeping by day in caves or crevices and
hunting shellfish at night.

The tail has a large notch underneath it. Bullhead sharks
have two large
dorsal fins with
spines.

» Scale

20

The bottom tail lobe is Becoming endangered
longer than the top lobe.
The common angelshark was once
The two dorsal » Scale found throughout shallow seas in
fins are farther the northeastern Atlantic. However,
back than the so many were fished that it almost
pelvic fins. became extinct, which means there
would have been none left in the world.
The Canary Islands, near Morocco, are
now the only place where you can still
see this angelshark.

Beautiful skin patterns pro
vide camouflage.

Common angelshark

The first gill slit is The mouth co FACT FILE
much larger than
the other four. ntains two kinds of t » Depth: Adults 0–36 ft (0–11 m)

This shark sometimes and young 0–490 ft (0–150 m)
walks on the seabed
using its paired fins. » Length: 3 ft (1 m)
» Fun fact: These sharks lay

corkscrew-shaped eggs that they
wedge into crevices in rocks to keep
them safe until they hatch.

eeth.

Horn shark

Horn sharks are found in different places
depending on their age. Pups live in shallow
waters and hunt by day, but they move to
deep water when older. Adults prefer rocky
areas and seaweed beds. They hunt at night.

21

Mackerel sharks Long gill slits allow
water to move fast
There are 15 species of mackerel shark, including over the gills
some of the largest, fiercest, and weirdest-looking underneath.
fish in the oceans. Despite their name, these sharks
don’t all feed on small fish. Some slurp plankton,
others hunt seals, and some scavenge on
dead whales.

Why mackerel sharks? New teeth grow
constantly to
Some sharks in this order like to eat small replace any gaps.
schooling fish, such as mackerel, which is how
they got their name.

Pelagic thresher » Scale FACT FILE

The pelagic thresher shark lives in the open The upper part » Depth: 0–1,800 ft
ocean. This timid shark has a small mouth to feed of the tail is
on small fish and sometimes squid. It is almost as long (0–550 m)
occasionally seen jumping as the body.
high out of the water » Length: 25 ft (7.6 m)
or, if it is really » Fun fact: Thresher sharks
unlucky, into
a boat! whip their tail to stun small
fish to eat.

Goblin shark » Scale FACT FILE

This may well be the oddest shark in the world. The » Depth: 885–4,270 ft
deepwater goblin shark’s shape and color suggest
that it lives close to the seabed and swims slowly. (270–1,300 m)

No other shark » » Length: 13 ft (4 m)
has a snout like » Fun fact: The goblin
this!
shark’s jaws can extend far
out to grab prey.

22

The tall first » Scale Great white shark
dorsal fin can be
seen when the This predator is very smart
shark swims at and inquisitive. It swims
the surface. constantly, migrating
thousands of miles a year
The torpedo-shaped to find prey. Youngsters eat
body is very muscular. small fish, but once grown
they hunt large marine
The symmetrical tail mammals.
fin indicates a very
fast swimmer. FACT FILE

Basking shark » Scale » Depth: 0–4,270 ft

This gigantic shark filters plankton from the (0–1,300 m)
water to eat. It feeds at the surface in cold
water but very deeply in the warm tropics. » Length: 20 ft (6 m)
» Fun fact: This shark is
Gill rakers
under the warm-blooded, so its body
gill slits sieve temperature is higher than
plankton the temperature of
from the seawater.
water.
FACT FILE
Sandtiger shark » Scale
» Depth: 0–3,940 ft
This calm, snaggly toothed shark is commonly
displayed in aquariums. Females give birth to (0–1,200 m)
one large pup every one or two years.
» Length: 33 ft (10 m)
Sandtiger » Fun fact: This shark can
sharks gulp air
to help keep filter 330,000 gallons
themselves (1.5 million liters) of
afloat. water every hour.

FACT FILE

» Depth: 0–660 ft

(0–200 m)

» Length: 10 ft (3 m)
» Fun fact: Sandtigers give

birth to the biggest pups
of any shark—about 3 ft
(1 m) long.

23

Carpetsharks The roughly equal
top-and-bottom parts of
There are more than 40 different types of the tail are a sign of a
carpetshark, including the largest fish in the long-distance swimmer.
world! All carpetsharks have two dorsal fins
and a mouth in front of their eyes. As their FACT FILE
name suggests, most have colorful patterns
and tassellike fringes, and many live on the » Depth: 0–3,280 ft
seabed—just like rugs or carpets on the
ocean floor. (0–1,000 m)

» Length: 59 ft (18 m)
» Fun fact: These huge sharks

give birth to hundreds of
pups that are about 2 ft
(0.6 m) long.

Blind shark The small eyes » Scale FACT FILE
close if this » Scale
This Australian shark has shark is taken » Depth: 0–460 ft
tiny eyes, but it isn’t out of water.
actually blind. It is (0–140 m)
nocturnal, which
means it feeds » Length: 4 ft (1.2 m)
at night and hides » Fun fact: This hardy
in holes by day.
shark lives in surf and rock
Nurse shark pools, and survives well in
aquariums.
This sociable shark sleeps in groups by day on
the seabed and hunts at night, vacuuming FACT FILE
prey quickly into its mouth.
It is often seen in aquariums. » Depth: 0–395 ft

The small mouth can (0–120 m)
suck sea snails right
out of their shells. » Length: 10 ft (3 m)
» Fun fact: Females only
24
give birth to pups every
second year. In between,
they take a rest.

Some divers hold on Whale shark
to the dorsal fin for a
ride—but that’s really This spotted giant is the largest fish
not allowed! in the sea—it can grow to longer than
a school bus. Despite its size, the whale
No one knows shark eats tiny fish, but lots of them.
what the three It travels huge distances through warm
ridges along both seas to find food, which it gulps down
of the shark’s sides with its enormous mouth.
are for.
Carpetsharks have
broad, flat heads,
with a mouth in front
of small eyes.

Huge, curved pectoral fins » Scale » Scale
provide “lift,” keeping the
whale shark near the surface. FACT FILE

Ornate wobbegong » Depth: 0–330 ft

This master of disguise is almost invisible because (0–100 m)
its patterned skin hides it as it lies asleep. At
night, the wobbegong wakes to prowl for food. » Length: 4 ft (1.1 m)
» Fun fact: “Wobbegong”
Fringes around
the mouth make is a native Australian word
it hard to see the meaning “shaggy beard.”
wobbegong’s outline.

Whitespotted bamboo shark FACT FILE

This common tropical shark is caught for food and often » Depth: 0–165 ft (0–50m)
kept in aquariums. It’s the only shark on this page that » Length: 3 ft (1 m)
lays eggs instead of giving birth. » Fun fact: This bamboo

This bamboo shark has body ridges, » Scale shark uses its muscly
like those on the whale shark. pectoral fins to crawl over
the seabed.

25

Ground sharks FACT FILE

Almost half of all shark species are ground » Depth: 0–260 ft (0–80 m)
sharks. Many live in deep water, but others are » Length: 20 ft (6 m)
common in all the world’s oceans. Most, such » Fun fact: Stingrays are the
as catsharks and houndsharks, are very small,
rare, and harmless. However, some are very great hammerhead’s favorite
large predators, although only a few are food, although they can defend
dangerous to people. themselves with sharp stings.

Great hammerhead

The great hammerhead is the
largest of the hammerhead
sharks. This species has a broad,
flat head filled with sense organs
for tracking down prey.

Blue shark FACT FILE
The world’s most common oceanic shark is the blue
shark. It cruises slowly along warm-water currents for » Depth: 0–1,150 ft
thousands of miles, hunting for squid and small fish.
Fishermen catch millions every year. (0–350 m)
The blue shark gets
» Length: 13 ft (3.8 m)
» Scale its name from its » Fun fact: Divers use bait
blue color.
to attract blue sharks for
cage diving.

Blacktip reef shark » Scale FACT FILE
This strong swimmer always hangs out on
Indo-Pacific reefs, where it is popular with » Depth: 0–65 ft (0–20 m)
divers. It is sometimes also kept in » Length: 7 ft (2 m)
aquariums. The black fin » Fun fact: Some of these
tip has a
white base. sharks have swum all the
way through the Suez
Canal, from the Red Sea
to the Mediterranean.

26

A very high, curved Only ground Huge hammer
first dorsal fin keeps sharks have a
the shark upright third, movable The broad, flattened head of a
when swimming. eyelid. Other hammerhead improves swimming
sharks can’t control and “lift,” which pushes the
close their eyes. shark up in the water. Widely
separated nostrils help the shark to
pinpoint the source of food smells.
The winghead shark has a head
width almost half the length of its
whole body!

More than 3,000
tiny sense organs
detect electrical
signals from prey.

» Scale

Pectoral fins are X-ray of a winghead shark
used for steering.

Pyjama shark The pyjama FACT FILE
The pyjama shark is a sort shark’s dorsal
of “catshark.” Named for fins are both » Depth: 0–330 ft
their stripes, these sharks close to
are only found in the its tail. (0–100 m)

waters around the tip of » Length: 3 ft (1 m)
South Africa, where they » Fun fact: These sharks
live in surf, caves, and » Scale
lay pairs of eggs, which
hatch on the seabed.

other rocky areas.

Leopard shark The lower tail » Scale FACT FILE
lobe is much
Despite its name, this shark is smaller than » Depth: 0–65 ft (0–20 m)
from the “houndshark” family. the upper one. » Length: 7 ft (2 m)
It lives in large schools, in » Fun fact: Females give
shallow water on the Pacific
coast of the USA and Mexico. birth to their pups in water
only 3 ft (1 m) deep.

27

Skeleton The eyes sit in a Shark teeth are made
cup in the skull, of hard enamel, not
called the orbit. cartilage, so they can
bite through prey.
A shark’s skeleton is not made
of bones. Instead, it is made of The tail, which contains
zigzag bands of muscle, is
light, flexible cartilage. This is more than half the length
the same material that your of this shark.

ears and nose are made of,

but stronger. There aren’t
many parts to a shark’s

skeleton, just a skull,

jaws, spine, gill arches, Jaw
and supports underneath
A shark’s jaws have to
be really strong so they
the fins. can bite hard. The jaws

aren’t fully attached to
the head, so they can
Great white reach out to bite prey.
shark skeleton
A shark’s body is supported
by the water around it, so its
skeleton can be bendier than a Gill arches
human’s. However, in very old,
large sharks, the cartilage Gill arches keep the gill slits
becomes much harder and open. The gill slits let out
more similar to bone. water that has come in
through the mouth and
passed over the gills. This
is how a shark breathes.

Movement Stiff fins push against
the water, helping the
The great white shark swims fast shark swim.
by beating just the end of its tail.
Long, thin sharks, such as this
dogfish, swim slowly, like an eel,
using most of their body length.

28

Cartilage Dorsal fin
rods and fin
rays support Shark and dolphin dorsal fins look very
the fins. similar, and they both stop sideways “rolling”
in the water. However, on the inside they are
completely different. Dolphins don’t have fin
rays to support their dorsal fin.

Dolphin dorsal fin Shark dorsal fin

Spine Vertebrae grow rings, like

The spine has about the inside of a tree trunk.
180 sections, called These can be used to tell
a shark’s age.

vertebrae, from the head
to the tip of the tail.
Human backbones are
only made up of about
30 bones. A shark’s spine
is also much bendier than
our backbone!

The large pair of pectoral ! WOW!
fins are for steering and
“lift,” pushing the shark Never pull a
up in the water. shark’s tail—it
can bend all the
way around to

bite you!

29

Inside a shark Stomach

Beneath a shark’s skin are hidden all the The J-shaped stomach
important parts it needs to survive. Its mainly stores food. The
muscles are attached to the inside of the thick shark can turn this inside
skin itself, not to the skeleton, like ours are. out, through its mouth, to
Underneath the muscles, the organs all play spit out inedible stuff that
a vital role in keeping the shark swimming. was eaten by mistake!

Brain Liver Dorsal fin

Shark brains come A shark’s liver is enormous,
in many different about 25–30 percent of its
shapes and sizes, body weight! It is full of oil,
depending upon the which is very light—lighter
senses the type of than water. This helps the
shark uses most. shark to stay afloat.
Nerves run from the
brain to all parts of
the body.

Gills Pectoral fin
(one of two)
Water comes in through the mouth and
goes out over the gills, which collect oxygen Heart
for the shark to breathe. Some sharks can’t
breathe if they stop swimming. Others can There are two main chambers in
pump water over their gills as they lie on a shark’s heart. One chamber has
the seabed. thick, strong walls, to pump blood
30 through the gills and all around
the body. The other one collects
returning blood.

Kidneys Denticles on the skin Skin
Shark skin is really thick. It is
Sharks aren’t waterproof! also covered in hard scales
Water seeps in through
their gills and skin. The called denticles. These
kidneys collect and get rid tiny interlocking teeth
of unwanted water. protect the skin and
also streamline it,
helping the shark
to swim faster.

Second
dorsal fin

Tail fin

Pelvic fin Anal fin
(one of two)
Warm-blooded

Muscles get hot when they work hard, but this heat is
quickly lost through the gills and skin. Most sharks are
cold-blooded, but some have a system that lets their
warm blood heat any cool blood returning from the gills
and skin, to keep themselves warm inside. This makes
them faster-growing and more efficient hunters.

Intestine

This is where food is digested.
A shark’s intestine is curled
into a very tight spiral, making
it look much shorter and fatter
than a mammal’s long
intestines.

Salmon sharks live in the North Pacific Ocean.

31

Shark eggs

Many sharks lay leathery eggs in nursery grounds—safe
places where shark mothers can anchor their eggs to the

seabed. The pups inside live off a yolk sac while they
grow into miniature copies of their parents—it may take
up to a year before they are ready to hatch. Many rays
and all chimaeras are also egg-layers.

Types of egg Fresh seawater Australian ghostshark egg
enters through Chimaeras, also known as
Sharks and their slits in the horns. ghostsharks, all lay eggs that
relatives lay eggs in are this shape. Adults migrate
pairs, but each species Spotted ray egg inshore to lay their eggs
has differently shaped Slimy strings and in shallow bays and
eggs. An empty, horns stop spotted ray estuary nurseries.
washed-up egg case is eggs from washing out
called a “mermaid’s of the nursery grounds Flat edges stop
purse.” It has an where they are left. the egg from
opening where the rolling around.
pup wriggled out.

Hatching An undulate ray The pup
hatches from uncurls its fins
The embryo of a its egg case. as it escapes.
growing shark, ray,
or chimaera curls up
to fit inside its egg.
Its tail pumps in fresh
seawater so it can
breathe, but it stops
if it senses danger.
When its yolk is
finished, the baby
wriggles out of its case.
32

Live birth A lemon shark pup being born

About 60 percent of sharks give birth Horn shark egg
to pups, rather than laying eggs. Some Horn sharks wedge their eggs
pups are born soon after hatching from securely under rocks and
eggs inside their mom. Others hatch into crevices. They hatch
earlier, and feed on spare eggs before 7–9 months later.
birth. A few sharks have placentas, like
mammals, which connect the mom to
the pup and provide them with food.

Tendrils wound
around seaweed
keep the eggs secure.

Smallspotted catshark egg Predators can’t
The smallspotted catshark’s easily pull this
miniature babies take about screw-shaped egg
8–9 months to hatch. Bigger out of its crevice.
moms lay bigger eggs!
! WOW!
Free at last! The empty
egg case may wash up Shark egg cases
on a beach nearby. are made from
the same material,
called keratin, as
your hair and

fingernails!

33

Baby sharks

Mother sharks never look after their young, and growing up
is a dangerous time. Big sharks often like eating little ones!
Many pups spend a few years hiding in places that big
sharks can’t reach. Others use a disguise to avoid being
spotted by hungry predators.

Lemon shark nursery ! WOW!
A mother lemon shark gives birth in the
place where she grew up safely. This Baby sharks
warm lagoon in the Bahamas provides are born with
shelter and food for lots of pups. They will teeth, ready to
spend four years living here with many
brothers, sisters, and cousins. hunt.

34

Stay away Adult zebra shark Zebra shark pup Sea snake
Adult zebra sharks These pups have black The stripes on this sea
Shark pups sometimes look have spots—they don’t and white stripes, but snake warn that it’s
very different from their look like a zebra at all! these aren’t to help venomous. Baby zebra
parents, not just in size but Only youngsters have them hide. They make sharks even swim like
also in shape and color. Pups stripes, as well as long, the pups look like sea snakes so that
are often camouflaged, thin bodies. dangerous sea snakes. predators stay clear!
which means their
appearance makes them
hard to spot. A few pups
disguise themselves as
completely different animals.

Nursery featuresSTPsahTuhhfhiepisadetlsnliyornsuowwgrosiptefmoslrayrofcaafgedrmrsoiunfaulottnnorsgdbhirtaoai,sbrvwkayeshwsteorhrearaerebrmsikitgs’psl.arfmiogsvhouiocdthone.thsoauofnet.
FTfotihdhsoeheedeylfaposgertoarthorwtenahpatuenunrdp.tismntgoanbegiagrtgo. Aveerssftihsahereyinfgusrlolligowhf oltiltlydtleer,
FSirpnccipauioeteerpnhmnersedstpmoiiassranrtunnesacuilsoohirttfnsuibteesedrsr.nayi—Tevihfnseoseghrouy. amnbevdaveebewadynriitlesehhctmaoitvmhvoeeenidrinses,addhbmiautvrhetikdaosuttahlers

35

Social sharks ! WOW!

Many sharks live in groups, called schools. Certain
Schools usually contain sharks of the same unrelated sharks
species and size, but not always. When living tend to hang out
side by side, these sharks need to be able together—they
to communicate with each other about
food and mates. might be
friends.
Types of behavior

Sharks need to cooperate when they are
hunting together, looking for a mate, or to
avoid fights. They use different signals to let
each other know what they mean.

Schooling Scalloped hammerhead sharks schooling
Sharks may swim together all the time, or only at
particular times during the day or year. Head-flicking Getting along
and swimming in spirals in these groups may let When different shark species school
other sharks know to keep out of the way. These together, they must be able to understand
behaviors may also be done to impress a mate. each other’s signals.

A great hammerhead and a nurse
shark swim together.

Glow-in-the-dark shark A swellshark glows green in moonlight.
This swellshark absorbs moonlight to make its
skin glow. Humans can’t see this light without
special cameras, but other swellsharks can.
Scientists haven’t yet decoded this secret signal.

36

Body language

tsastMchuhSstooershaasmoderabmnnekrtmeycskghasi,essluetdlohrienecm.rraraiTwbcrsanskahhothh’tteidobaoes.twyreaiwckhsplawskianobt,vwhhsibpgiioioteugrlilrweaetosavcrnotvhaehauorntnoeleoitddytduhfmcliseagaerrahnd.gkteesr,

Size display
osAhf saairzskecshdaoirsoepli,lnawychhsihlaeorgwsmes. aTwlhlheeircbohingoegusethsotafsvthewatrooksshhgaanertgkstooiusstlwaaritmgtehirne—tehbdeiggmegsei.dr dle

Splashing
tsTrhayaiilnrskglsatpaorsesacfraeereecdoeinmagcmhtooognthewtehhreearnw. Tasheyevfersorhamalrgkthrseemairtafwyohboidete. Swim-by
TAhsislogwivsewsismha-brkysisaachgaonocdewtoaysetoe icfhtehcekyokuntoawnootnheearnsohtahrke.r.
WARNING!

Circling Hunching
Sometimes mA ehaunnsc“hSetdaybaawcka,ywfritohmthmeeh!eI’alldbuitpe,iaf nyoduficnosmpoeincltoesderd!”own
feeding in a sharks circle emaicghhot tbheedr ebceifdoirneg
who gets to group. They
start first.

37

Match the prey with the shark that eats them! 3 Tuna

1 Crab Shortfin mako shark teet

Squid 2
Port Jackson shark teeth
Basking shark mouth

h

A Port Jackson B Basking C Shortfin
shark shark mako shark
Sharp teeth at the front Filter feeders use gill Needlelike teeth
grab prey, while rounded rakers to sieve out pointing backward
pads at the back grind up their tiny food from mean slippery prey
tough food. seawater. can’t escape this shark.

Dinnertime Conveyor-belt teeth

It is possible to guess what sharks prefer Sharks lose all their teeth every
to eat from the shape of their teeth— month or two, but a replacement
set moves forward right away.

particularly if they are choosy. Some

sharks catch and swallow their dinner
whole. Others have jagged teeth like

knives that cut up larger prey. A few Sandtiger sharks
have grinding teeth for smashing up replace one tooth
tough shells. every two days—that’s
more than 10,000
in a lifetime!

38

Big teeth

Big teeth are used to bite chunks out of animals that
are too large to be swallowed whole. The biggest-ever
shark teeth are from the prehistoric shark Megalodon.
These teeth are 7 in (18 cm) long.

4 Plankton Megalodon tooth !
This tooth is between LIFE SIZE!
Great white shark teeth 2 and 16 million years old.
It is a fossil from a huge
Megalodon. This shark
probably ate whales.

D Great white
shark
Jagged, pointed
teeth bite out
chunks of large
prey for this
shark to swallow.

Great white
shark tooth
The great white shark’s teeth
have serrated edges for
sawing off chunks of flesh as
the shark shakes its head
from side to side.

Answers: A2 B4 C1 D3 39

Surprise attack The eye is rolled
back to avoid being
Great white sharks suprise damaged by prey
prey by attacking from during an attack.
below. Tourist boats in
South Africa tow model
seals to encourage the
sharks to breach out of the
sea—don’t try this yourself!

Hunting ! WOW!

There are no vegetarian sharks! Many sharks
All of them are hunters, but they change tooth
catch their dinner in different shape and their
ways. Some sharks dig for favorite food as
shellfish in the sandy seabed,
while others hide and ambush they grow.
passing prey. The fastest
swimmers chase down squid
and fish, grabbing them with
razor-sharp teeth.

40

Test bite Galapagos shark
This shark is
“mouthing” a boat’s
engine to decide
whether it’s good
enough to eat.
Sharks often give
objects a test bite
to find out whether
they are edible.

Blacktip reef sharks

Cooperative
Some sharks hunt in packs, working together
to herd, confuse, and capture shoaling prey
that would escape a lone hunter.

Cookiecutter shark Australian angelshark

Quick bite Ambush
Light given out by these tiny sharks Flat sharks use their patterned skin and
may attract larger predators. If the a light covering of sand for camouflage.
predators get too close they can end They hide and wait for unwary prey to
up losing a cookie-shaped mouthful swim too close, then jump out at them.
of flesh to these little monsters.

41

Filter feeders

The world’s biggest sharks feed on the smallest animals—
plankton. Because plankton are tiny, they have to be
filtered out of seawater—teeth are useless! Filter feeders
use their gills to trap plankton, as well as for breathing.

Whale shark
This shark stops swimming to take
huge gulps of water. It closes its
mouth to push the water over its
gills, straining out the plankton
and squeezing the excess
water out of its gill slits,
before swallowing
its catch.

42

Plankton Gentle giants

Plankton includes all Divers love swimming with these huge
sorts of tiny swimming sharks because they don’t have big teeth
and floating animals, or bite, and aren’t dangerous.
including crabs and
other shellfish, miniature
eggs, and baby fish.

Basking shark with mouth open, showing
open gill slits

Basking shark
The basking shark is a “ram feeder”—it never
stops swimming and lets water pass over its gills
continuously. It collects minute plankton at the
surface and in deep water.

! WOW! Photographtshoefymlievgeainmvoeurtyhdseheaprkwsaatreer.rare because
Megamouth shark
Filter feeders This deepwater plankton eater has never been
have tiny teeth seen feeding, but probably gulps mouthfuls of
water, like the whale shark.
because they
don’t chew 43
their food!

Human senses Hearing
Our ears collect sound,
A human’s five senses are which travels to internal
sight, hearing, smell, taste, sense organs that detect
and touch. Our sense organs vibrations—and gravity.
detect signals such as light,
noise, and pressure, and then Sight
send messages to the brain, A lens inside our eyes
which tells the body how focuses light onto special
to react. cells that detect light
and color.

Smell
The inside of the nose is
full of tiny cells that can
detect thousands of
different smells!

Senses Taste
Taste buds on
Animals need senses to find top of our tongue
out about the world. They are detect salty, sweet,
essential for locating food and bitter, sour, and
avoiding danger. Signals are savory tastes.
detected by sense organs. Most
sense organs are on the head, Touch
but one covers the whole The skin is our biggest
body—it’s the skin! Sharks have sense organ. It detects
the same five main senses as us, pressure, or touch, and
but some are higher-powered temperature.
than ours. They also have an
amazing sixth sense—they can
detect electricity.

44

! WOW!

Taste
Sharks have taste cells
inside their mouth Some sharks
and on their could smell
barbels—if they a scrap of food
have them.

in an Olympic
swimming
Electroreception Smell pool.
This extra sense Sharks have
detects tiny electric
fields from living a fantastic
animals and the
Earth’s magnetic sense of smell.
field. It helps sharks
to find food and They don’t use
navigate through
huge oceans. their nostrils for

Shark senses anything else!

Five of a shark’s senses Sight
are like ours, but they The eyes of sharks living
have a special sixth sense in shallow, clear water
called electroreception. are very like ours.
Sharks can also sense Deepwater sharks need
touch without being in huge eyes to capture the
contact with an object,
using special receptors tiniest glimmer of light.
down the side of their body.
Hearing
It’s almost impossible to
see the tiny openings
leading to a shark’s ears.
On the inside, they are
very like ours.

Lateral line
The lateral line can be found
running along the sides of sharks
and other fish. Tiny organs inside
it detect pressure changes in the
water—a remote sense of touch.

This helps them find moving prey.

45

Sensing Hunting rays
electricity
Sharks use their eyes, nose,
and electric sense organs
to find prey. Scent is a
long-distance clue and
sight is useful closer up,
but electroreception is
Sharks have an amazing super-sense, important when prey is
called electroreception. They use special only inches away—even
cells, known as ampullae, scattered under when it’s hidden
from view.

their head and around their mouth to

detect electricity. All animals produce tiny

amounts of electricity, and electroreception
can pick this up. Electroreception is also
useful to help a shark find its way on long
journeys, as it can identify the direction ! WOW!

of the Earth’s magnetic field. Deepwater sharks

chew underwater
phone cables
Torpedo ray because the wires
produce electric
Torpedo rays generate electricity in special
cells. They store it in “battery” organs and fields!
then release it as electric shocks to stun prey
or for defense. A common torpedo ray can

produce 200 volts. Ancient Greek doctors

used electric rays to shock patients for pain

relief, but don’t try this at home!

Common torpedo ray Electric field
All animals‘ muscles produce
46 tiny pulses of electricity that
form electric fields. Electricity
travels well through salty
water, so sharks can pick
it up to find hidden fish.

Optic nerves Electrical sensors
These nerves carry signals The ampullae are tiny pores
from the eyes to the brain, filled with jelly. Electricity
so sharks can see their travels through them to tell
surroundings. Eyes that are the shark where prey is.
far apart give hammerheads Ampullae around the mouth
an almost 360o view. can detect one-billionth of
a volt—wristwatch batteries
Brain are only 3 volts!
Hammerheads have
larger brains than other ly visible on the undersi
sharks because their de of a shark’s head.
sense organs produce
so much information.

Pores are clear

Smell organs Hidden stingray
Information about scent Rays often hide underneath a
is sent from the smell layer of sand. A hammerhead can’t
organs in the nose to the see directly beneath its head, but
brain. A hammerhead’s electroreception tells the shark
nostrils are almost as exactly where its dinner is!
widely spaced as its eyes.
This helps it to pinpoint 47
the source of a smell.

Where do Freshwater
sharks live?
It is rare for sharks to live in freshwater.
Sharks live almost everywhere The only ones that do live in warm, tropical
under water. They are found in rivers. A few species can adjust to changing
the open ocean, shallow and salt levels, and travel back and forth between
deep seas, and even some rivers. freshwater and the sea.
However, most kinds of shark
choose to live in one particular Coast
part of the ocean. You may even
need to watch out on land—the Many small, harmless sharks spend their
epaulette shark can sometimes entire lives in the shallow water near the
be found walking on the shore. Some may live unseen just a few feet
shoreline! away from beachgoers.

The walking shark Coral reef

The epaulette shark of New Guinea and Australia Coral reefs provide habitats filled with food
is able to survive out of water for short periods in otherwise empty tropical seas. Sharks use
of time. It scuttles between rock pools on its the reefs as homes, or may visit occasionally
muscular fins. However, the shore can be to hunt for food.
dangerous and it has two large eyespots near
its pectoral fins to scare predators away. Open ocean

Epaulette shark Oceans are home to long-distance travelers.
Some sharks commute daily from the surface
48 to a depth of 1,640 ft (500 m) and travel
thousands of miles a year.

Seafloor

The sharks that live on this rich feeding
ground don’t need to travel far to eat. The
seafloor is home to many types of shark that
never move far away from the sandy bottom.

Deep sea

Very little light reaches this cold, barren
habitat. It is home to sharks that can glow
in the dark and others with huge, green eyes
that can see the slightest glimmer of light.