There are bigger mammals, too, such as hippos, rhinos, elephants and giraffes - not to mention the many birds, including ostriches. Mammals of the plain Impala spend most of their life grazing, but can leap and run very fast to escape lions. Giraffes ' long necks enable them to reach leaves high up in trees. Zebras' stripey markings make them much harder for predators to spot. Lions find plenty of prey among the grass-eaters.
Many mammals live in the sea.
Seals, walruses and sea cows have fur and blubber, a thick layer of fat, to keep them warm. Whales, dolphins and porpoises have only blubber. Whales, dolphins and porpoises are together known as cetaceans. Many are among the most intelligent and gentle of all creatures. They can stay under water for some time, but cannot breathe there and must come up for air every now and then.