DK - WOW! The Visual Encyclopedia of Everything

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FISH

Fish were the first vertebrates, and the ancestors of all amphibians, reptiles, mammals, and birds. They are perfectly adapted for life in water, which supports their bodies and provides them with vital oxygen. There are two main fish groups: those with bony skeletons, and the sharks and rays, which have skeletons of flexible cartilage.^11

ECHINODERMS

Sea urchins, starfish, feather stars,

and sea cucumbers are echinoderms, meaning “spiny skinned”. Their bodies tend to be wheel-shaped, with a central mouth. Feather stars trap food that floats through their feathery arms, but most search for food on the seabed.

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REPTILES

Although cold-blooded like amphibians, reptiles such as snakes and lizards have waterproof, scaly skins that allow them to live in dry places such as deserts. Most are active hunters, and some snakes have powerful venom, which they use to kill their prey and for defence, if threatened.

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MOLLUSCS

Most molluscs are soft-bodied animals that

live in water and have protective shells. They include mussels, clams,

and whelks. The only molluscs able to live on land are the snails and slugs. Octopuses and

squids are also molluscs, but they are highly evolved, with well-developed

brains and eyes.

Sticky pads on the frog’s toes give good grip^8

CRUSTACEANS

Like insects, crustaceans have hard external skeletons with several segments, and strong jointed legs. All are aquatic, apart from woodlice. They include tough-shelled

animals like crabs and lobsters, as well

as more delicate shrimps and water fleas. 9

MIRIAPODS

Named for their many legs, miriapods

have long bodies divided into segments. Centipedes have a single pair of legs on

each segment, while millipedes have two

pairs. Some millipedes have more than

90 segments, and more than 180 pairs of

legs. Millipedes eat mainly dead material,

but centipedes are speedy hunters.

Suckers on each arm help the octopus move around and grab prey

A millipede’s legs are moved by a wave-like action of the body

The powerful claws of this lobster can seize and crush prey

Lion’s paw has soft pads for running and sharp, retractable claws

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Like other reptiles, snakes have scaly skin

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