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.