Once numerous in all African rivers and streams with deep water, the hippopotamus is now largely restricted to parks and wildlife refuges. This huge animal averages between 1.1 and 2 t (1.2 to 2.2 tn.) and can weigh as much as 4.5 t (5 tn.).
The body of a hippopotamus is so sparsely covered by hair that it appears naked. In its skin are pores which exude droplets of moisture that contain red pigment; as light is reflected through these droplets they appear red. This extrude is a natural sunscreen, and helps to keep the skin moist when out of the water.
The hippopotamus is perfectly at home in the water, mating and giving birth there. Due to its specific gravity, it can submerge itself completely and walk on the bottom of the river. It comes up on land for about five hours every night to feed on grasses and crops. The hippopotamus is most dangerous when it feels cut off from the relative safety of its watery environment.