Hippo entering the Zambezi River.

The hippopotamus, or hippo, is a large, mostly herbivorous mammal in sub-Saharan Africa, and one of only two extant species in the family Hippopotamidae. The name comes from the ancient Greek for "river horse". After the elephant and rhinoceros, the hippopotamus is the third-largest type of land mammal and the heaviest extant artiodactyl.