The hippopotamus (Hippopotamus amphibius), or hippo, from the ancient Greek for "river horse", is a large, mostly herbivorous mammal in sub-Saharan Africa, and one of only two extant species in the family Hippopotamidae (the other is the Pygmy Hippopotamus.) The hippopotamus is the third largest land animal (after the elephant and the white rhinoceros).
During the day they remain cool by staying in the water or mud; reproduction and childbirth both occur in water. They emerge at dusk to graze on grass. While hippopotamuses rest near each other in the water, grazing is a solitary activity and hippos are not territorial on land.