hippopotamus

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Large herbivorous, short-legged, even-toed hoofed mammal. The common hippopotamus (Hippopotamus amphibius) is found in Africa. It weighs up to 3,200 kg/7,040 lb, stands about 1.6 m/5.25 ft tall, and has a brown or slate-grey skin. It is an endangered species. (Family Hippopotamidae.)

Hippos are social animals and live in groups. Because they dehydrate rapidly (at least twice as quickly as humans), they must stay close to water. When underwater, adults need to breath every 2–5 minutes and calves every 30 seconds. When out of water, their skin exudes an oily red fluid that protects them against the Sun's ultraviolet rays. The hippopotamus spends the day wallowing in rivers or waterholes, only emerging at night to graze. It can eat up to 25–40 kg/55–88 lb of grass each night. The pygmy hippopotamus (Choeropsis liberiensis) lives in West Africa.

There are about 157,000 hippos in Africa (1993 estimate), but they are under threat from hunters because of the value of their meat, hides, and large canine teeth (up to 0.5 m/1.6 ft long), which are used as a substitute for ivory.