The word hippopotamus comes from two Greek words meaning river horse. Its scientific name is hippopotamus amphibious. Like some other ungulates, the hippo is an artiodactyl, with four-toed feet. Hippos found in the sub-Saharan Africa region have a really big head and mouth and a very thick, greyish skin supported on short legs.

Hippos spend most of their time wallowing in muddy pools and even rivers. Most of their body is submerged, with only the nostrils, eyes and ears out to pick up signs of danger. Although they appear calm, male hippos fight over territories and ward off potential enemies by baring their canines. Towards dusk, hippos leave the water to graze for grass, their chief diet, walking for hours at a stretch through the night. A rhino can eat as much as 68 kg in a single night.