homework encyclopedia

96 Nature

Animals

Animals are grouped into two main types – vertebrates

with an inner skeleton, including a backbone, and

invertebrates, without a backbone. As many as ten

million species (different kinds) of animals – all with

their own modes of. BEHAVIOUR – live on Earth.

1 CHAMELEON

A chameleon is

camouflaged to blend

in with its surroundings

and moves around slowly

to avoid detection by its

predators and prey. To feed,

the chameleon shoots out its

tongue at a lightning-fast

speed to hit insects before

they have time to react.

WHICH FEATURES DO ALL ANIMALS HAVE IN COMMON?

All animals have bodies made up of many different cells

and eat other organisms to survive. Unlike plants or

fungi, which are rooted in one place, animals

move about to find food, escape from enemies,

and find a mate. Almost all animals

breathe oxygen, either from the air

or from water.

WHAT IS THE WORLD’S

FASTEST ANIMAL?

The world’s fastest animal

is the peregrine falcon,

which can exceed 200 km/h

(124 mph) when diving through the

air after prey. The fastest-powered flight is that of

the spine-tailed swift. It travels at up to 170 km/h

(106 mph). The quickest animal in water is the

sailfish, which can swim at up to 109 km/h (68 mph).

HOW BIG DO ANIMALS GROW?

Some animals grow to enormous sizes. The world’s

biggest animal, the blue whale, may reach 28 m (92 ft)

long and weigh almost 150 tonnes (147 tons). On the

other hand, some animals are too small to be seen with

the naked eye. The world’s tiniest animals are creatures

called mesozoans. They consist of fewer than 50 cells

and measure just 0.5 mm (^1 ⁄ 50 in) in length.

WHAT ARE WARM-BLOODED ANIMALS?

Warm-blooded animals are those that generate their

own body heat from food. Birds and mammals are

warm-blooded. All other animals, including fish,

reptiles, amphibians, and insects, are cold-blooded.

Their body temperatures rise and fall with the

temperature of their surroundings. These animals

are less active in cold weather but require less food.

1 COLD SHOWER

The Asian elephant is the world’s

second-largest land animal (the

African elephant is the largest). Like

all mammals, it is warm-blooded.

Due to their size, elephants can

have trouble keeping cool. One

solution is to seek water. Elephants

also flap their ears to cool the

blood flowing through them.

4 WORKING TOGETHER

Leaf-cutter ants live in colonies

of closely related individuals, all

hatched from eggs laid by a single

queen. Most become worker ants.

Long legs

increase stride

and speed

Muscles

drive the

animal forward

after prey

CHEETAHS 3

The cheetah is the world’s

fastest land animal,

capable of speeds of

up to 96 km/h

(60 mph) in short

bursts. It hunts by

ambush, creeping as

close as it can to its

prey before rushing

in for the kill.

animals