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HABITATSENVIRONMENT FOR PLANTS AND ANIMALS

Creaturesof the Deep

Copyright © 2010 Top That! Publishing plcTide Mill Way, Woodbridge, Suffolk, IP12 1AP, UK

www.topthatpublishing.comTop That! is a trademark of Top That! Publishing plc

All rights reserved

The Ocean and theWorldPages 4–5

Living in the OceanPages 6–8

The Sunlight ZonePages 9–11

The Twilight ZonePages12–13

The Midnight ZonePages 14–15

The Sea FloorPages 16–17

Into the AbyssPages 18–20

Living in ParadisePages 21–23

Ocean of IcePages 24–25

The Big BitePages 26–28

Our Best Friends?Pages 32–33

CONTENTS

2

Royalty of the DeepPages 29–31

Ocean GlidersPages 34–35

Spineless GeniusPages36–38

Cold-Blooded KillersPages 39–41

Handle with CarePages 48–49

Science and the SeaPages 50–52

Bringing Up BabyPages 45–47

CONTENTS

The Big OnesPages 42–44

Fishy FactsPages 59–61

3

The ResourcefulOceanPages 53–55

Endangered SpeciesPages 56–58

Had you been around 400 million years ago, youcould have swam with armoured fish and crab-likecreatures called trilobites. When dinosaurs ruled Earth,230 million years ago, marine reptiles calledplesiosaurs swam in the oceans. The 20 m (65 ft)shark, calledmegalodon,ate whalesfor breakfast20 millionyears ago!

4

Life evolved in the ocean three billion years before itdid on land. The first ocean was full of tiny chemicalparticles. Billions of years ago, these particles formedliving cells. The first life forms were bacteria and algaethat ‘ate’ poisonous gases – like hydrogen sulphideand carbon dioxide – and ‘pooed’ oxygen. These bacteria and algae made the world inhabitable forother creatures.

Earth was just another big rock flying through space 4.5 billion years ago. As the outer layer of our planet cooled to form a solid crust, water wasreleased into the atmosphere. A giant ocean formed – and life began.

THE OCEAN AND THE WORLD

What creatures lived in the primeval oceans

How did the first ocean create life

Earth’s earliest life forms

A trilobite andan armoured fish

The megalodon shark grew up to 20 m (65 ft) long –that’s as long as 6 cars!

5

Until 250 million years ago, Earth’s surface was asingle landmass called Pangaea. Pangaea wassurrounded on all sides by an enormous ocean calledPanthalassa. Pangaea was torn apart by volcanicactivity and eventually became today’s continents. As this happened, Panthalassa also split into oceans.

When were today’s oceans formed

Oceans are incredibly important for life on Earthbecause they provide most of the oxygen we breathe.Ocean currents keep the planet’s temperature constantby absorbing the sun’s warmth and moving it aroundthe globe. Evaporation from the oceans helps to makerain – giving plants and animals water to drink.Scientists estimate that 230,000 forms of marine lifeare currently known, but there could be thousandsmore yet to be discovered.

Why are oceans important for life

There are five oceans: the Pacific, the Atlantic, theIndian, the Arctic and the Southern. Together theycover just over 70% of Earth’s surface in salt water.Sea water is salty because of minerals, like calciumcarbonate, dissolved in it. Calcium carbonate is foundin animals and in rocks and sand.

What are today’s oceans called

The single landmass, Pangaea, split into thecontinents we know today

6

The oceans are full of sea creatures of all different shapes and sizes.What’s life like under water and how do living things survive down there?

What do sea creatures eat

Marine animals depend on each other for food.This can be demonstrated with a food chain. It workslike this: predators eat other fish; these fish eat tinycreatures called plankton; and plankton eat bacteria.The smallest plankton feed on sunlight and produce theoxygen that keeps all other sea creatures alive.

LIVING IN THE OCEAN

Sea creatures need oxygen, just like us. Luckily forthem, water has oxygen dissolved in it. Most fishbreathe through openings called ‘gills’ on their heads.Sea water flows into the gills and over blood vessels.Oxygen ‘molecules’ move from the water into theblood – and are carried around the fish’s body.

How do sea creatures breathe

Sea creatures need oxygen,just like us

7

Phytoplanktonare eaten bysmall creaturescalled zooplanktonwhich, in turn, areeaten by tiny animalssuch as crabs,jellyfish, corals and worms

Thesecreatures, in

turn, becomefood for fish. Big

fish eat smallerfish. At the top of

the food chain arefishermen, large

predatory fish such assharks, together with

mammals such as sealions, as well

as some species of seabirds

Phytoplanktongain much

of their energyfrom the sun

Over thousands of generations, sea creatures havedeveloped clever ways to protect themselves – andattack their ‘prey’. Many animals use disguise or‘camouflage’ to hide from their potential predators,which enables them to blend into their surroundings.Others do the opposite: their bright colours arewarnings to predators. Some use poison to attack prey or defend themselves.

How do marine animals protectthemselves

Why are fish that funny shape

Fish have no legs or arms and have a curvy or‘streamlined’ shape. This makes it easier for them tomove through water. As you may know from swimming, water is heavy – it weighs down or exerts‘pressure’ on you. Marine animals have a large bodysurface to withstand this pressure. Fish use their fins forswimming and, in some species, for gliding or crawling. They also help a fish move forward, turn and keep in an upright position.

A fish’s streamlined body

FACT BYTES

The oceans provide 99% of the space availablefor life on Earth!

Camouflaged sea creatures

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