The hippopotamus is a large semiaquatic mammal native to sub-Saharan Africa.
Hippos inhabit rivers, lakes, and mangrove swamps. Territorial bulls each preside over a stretch of water and a group of five to thirty cows and calves. Mating and birth both occur in the water. During the day, hippos remain cool by staying in water or mud, emerging at dusk to graze on grasses.
Hippos are among the most dangerous animals in the world due to their aggressive and unpredictable nature.