Science Series Level 4 Level 4 S y ste m s S y ste m s The Powerful Weapon Of The Jellyfish
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Systems Level 4 6 Animal Body Interesting Information The jellyfish is a planktonic aquatic animal belonging to the class of Scyphozoa with about 200 species. The term ‘jellyfish’ is also commonly used for free-swimming aquatic invertebrates with transparent bell-shaped bodies and stinging tentacles around the edge, such as salps or comb jellies. Sally, let’s swim further out from the beach! Both of you have to come ashore right now! Vincent, what’s wrong with the sea? Oh no! The jellyfish has appeared on the surface of the ocean. Hey, Sean! I think we should just stay near to the beach. Eh? What’s this beautiful creature? Sean and Sally are spending their summer holiday on Phi Phi Islands in Thailand ... Hup Lick Publishing (M) Sdn Bhd All Rights Reserved
Systems Level 4 7 Interesting Information Jellyfish can be found in cold and warm, deep and shallow waters along coastlines. They can be found in oceans all over the world. They appear to be drifting and pulsing along on the ocean currents. Guys, there are jellyfish in the sea. Please come ashore to avoid being stung. Help! Help! Stay calm. I’m coming to rescue you now. He must be sent to the hospital at once. He must have been stung by the jellyfish. Ouch! I feel thousands of very tiny stingers on my arms and a sharp, burning pain. Hup Lick Publishing (M) Sdn Bhd All Rights Reserved
Systems Level 4 8 Interesting Information Although they are called jellyfish they are not fish because they are gelatinous and boneless invertebrates. They have a smooth bag-like bell-shaped body and tentacles with thousands of tiny stinging cells but do not have a brain and a heart. Jellyfish absorb oxygen from water through their membranes. The beautiful creature that I saw just now must be the jellyfish. Vincent, why do jellyfish sting? We’re fortunate because Vincent stopped us just now. He’s really an experienced lifeguard who knows everything about beach safety. The jellyfish normally use their stingers to act as a defence mechanism or to paralyse their prey. There are thousands of tiny stinging cells called cnidoblasts in each of their tentacles. The cnidoblasts are lined with nematocysts containing stinging threads. Trigger Stinging thread An undischarged capsule of cnidoblast Hup Lick Publishing (M) Sdn Bhd All Rights Reserved
Systems Level 4 9 Interesting Information The venom of a jellyfish is a complex mixture of proteins and polypeptide compounds that contain antigenic and toxic effects. Common symptoms of jellyfish stings include burning and stinging pain, purplish hives on the skin, muscle pain or even difficulty in breathing. When a jellyfish encounters its prey, the pressure inside the nematocyst will cause the stinging thread to inject venom into its prey. A discharged capsule of cnidoblast Nematocyst Discharged thread The venom is a neurotoxin that paralyses the jellyfish’s prey. Larger jellyfish have larger cnidoblasts that can penetrate deeper into the skin of the prey. Stinging thread Nematocyst Skin Generally, the venom can kill small aquatic animals but it also poses a danger to swimmers and fishermen as it can be fatal. The jellyfish is such a deadly Hup Lick Publishing (M) Sdn Bhd creature! All Rights Reserved
Systems Level 4 10 Interesting Information The flame jellyfish, scientifically known as Rhopilema esculentum, is a jellyfish species native to the warm waters of the Pacific Ocean. It is a popular seafood amongst the Chinese, Japanese and Koreans. I must put a sign on the beach to warn others to be careful of the jellyfish. Eh? Is the fisherman collecting the jellyfish that are washed up onto the beach? Eating jellyfish is nothing unusual to us! Come with me, I’ll prepare you a jellyfish meal. About 25 to 30 species of jellyfish in the world are edible, including the flame jellyfish that the fisherman is collecting. I want these flame jellyfish for lunch. Don’t jellyfish contain deadly toxin? STINGERS Hup Lick Publishing (M) Sdn Bhd All Rights Reserved
Systems Level 4 11 Interesting Information It was estimated that 150 million people worldwide are being stung by jellyfish annually, with hundreds of fatal cases. If you are stung by a jellyfish, rinse the sting site with vinegar or take a hot shower to relieve the pain. Go to the hospital immediately if you have breathing difficulties or have been stung in the eye or mouth areas. The jellyfish are stripped of their tentacles and the mucous membranes are scraped off. It’s safe to eat them now. Let’s tuck in! I didn’t know that jellyfish can be eaten raw and has a crispy texture. Mmm ... This jellyfish dish is tasty. Thanks for the treat! Bye! It’s the bell and the structures around the mouth holding the stinging cells of the jellyfish that give the crunchy texture. Bell-shaped body Oral arms Tentacles Hup Lick Publishing (M) Sdn Bhd All Rights Reserved
Systems Level 4 12 Jellyfish are the oldest living organisms on Earth and they have been around even before the dinosaurs. Scientists discovered a jellyfish fossil that was thought to be more than 500 million years old. Dinosaurs roamed the Earth from about 250 million to 66 million years ago. Most jellyfish species are hermaphrodites, which means they have both male and female sex organs in the same body. Therefore jellyfish do not reproduce inside their bodies as most animals do. They undergo external fertilisation where ovules and sperms will be released outside the body to be fertilised. In 1991, about 2,000 moon jellyfish were brought into the Space Shuttle Columbia to test their reaction to microgravity. The jellyfish multiplied to a population of 60,000 while in space. However the offspring produced in space had difficulties dealing with Earth’s gravity. Fascinating Facts About Jellyfish Photo Source: Aaron Sappenfield/University of California, Riverside Hup Lick Publishing (M) Sdn Bhd All Rights Reserved
Systems Level 4 13 Science Education Extension: Enter and key in “Jellyfish predate dinosaurs. How have they survived so long? - David Gruber” (reprint YouTube) A jellyfish species known as the Turritopsis dohrnii is the only known immortal creature on Earth. They do reproduce, but they do not die because they can transform themselves back into their polyp state by retracting their tentacles and shrinking their bodies. They can keep repeating the cycle unless they get eaten by fish or contract a disease. About 85% to 98% of a jellyfish consists of water. They will almost disappear when the water content evaporates as they are washed up on the beach. Human activities that lead to global warming and pollution are causing many animal populations to decrease at an unprecedented scale. However, the jellyfish population is booming despite human activities as they can thrive in warmer water with less oxygen. Hup Lick Publishing (M) Sdn Bhd All Rights Reserved
A system is an entity composed of interlinked parts that collectively perform one or more functions. T h i s i n c l u d e s b o t h n a t u r a l systems, such as the digestive and respiratory systems that manage biological processes, and humanengineered systems, like electrical grids that power our cities and decimal systems that underpin our mathematics. Understanding these systems provides insights into their mechanics and how each component influences and interacts with others to fulfill specific functions. Science Series Level 4 Level 4 S y ste m s S y ste m s All Rights Reserved Printed by: Percetakan Tatt Sdn. Bhd. (270731-D) Lot 17485, Jalan 2, Taman Selayang Baru, Batu 8 Jalan Ipoh, 68100 Batu Caves, Selangor. Tel : 03-6136 6686 Faks : 03-6136 8676 WM: RM16.00 EM: RM17.00 Publisher: HUP LICK PUBLISHING (M) SDN. BHD. (106567-K) 40, Jalan Metro Perdana Barat 12, Sri Edaran Industrial Park, Off Jalan Kepong, 52100 Kuala Lumpur. Tel: 03-6258 9471 Fax: 03-6258 7795 English translation rights granted to YOUNG SCIENTISTS PTE. LTD. ISBN 978-629-488-101-3