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Hippopotamus, Africa south of the Sahara, up to 4 m (14 ft) long, 1.5 m (5 ft) high at the shoulderHippopotamuses are large African semi-aquatic mammals: they live both in the water and on land. They are ungulates, mammals that have hooves instead of claws. The hippo is classified as an even-toed ungulate, along with pigs, deer, camels and others, although their closest living relatives are now thought to be whales and dolphins. Hippos live in groups of up to 30 individuals in grassland rivers and lakes. They feed on grasses on land at night. The hippo's smaller, more solitary, relative, the pygmy hippopotamus, lives in forests and swamps.


A hippo standing on the lake bottom with just the top of its head above water.Hippo grazing on landThe skin of a hippopotamus dries out quickly in the hot African sunshine, so hippos spend around 16 hours a day lazing in cool water or mud. Their eyes, ears and nostrils are high on their heads, so that they can submerge almost their entire bodies. Hippos stir up the bottom mud, providing nutrients for other swamp life. They even mate and give birth in the water. 

The name hippopotamus comes from the ancient Greek words hippos, meaning "horse" and potamos, meaning "river". So its complete name means "river horse".

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