There may be 30 million different kinds altogether, ranging from microscopic parasites that live in people's blood to whales more than 30m long.
Animals are creatures that are born, grow up and die.
They move about, eat and breed and can sense the world around them in a variety of ways - by sight, hearing, touch, smell and taste. Animal habitats Animals live in an enormous range of places. Each place or habitat has its own special combination of animals. The seas are teeming with animal life, from tiny sea anemones that cling to seashore rocks to worms that live in the black ocean depths where daylight never penetrates. Rivers, streams and lakes have their own animal life too, including many fish and insects.