The hippopotamus (Hippopotamus amphibius), from the Greek word 'ιπποπόταμος (hipopotamos, hipos meaning "horse" and potamos meaning "river"), is a large, mostly herbivorous African mammal. It is one of two extant (recently three or four extinct) species from family Hippopotamidae This family also includes the pygmy (dwarf) hippopotamus (Choeropsis liberiensi).
Although the number of hippos is estimated at 125,000 to 148,000 individuals, they are still threatened by hunting and loss of natural habitat.
Taxonomy and Origin
Hippopotamus is the type genus of the Hippopotamidae family. The pygmy hippopotamus does not belong to the same genus of this family as the hippopotamus, but either Choeropsis or Hexaprotodon. Hippopotamidae are sometimes called hippopotamids. Sometimes the subfamily Hippopotaminae is used. Further, some taxonomists group hippopotamuses and anthracotheres into the superfamily Anthracotheroidea. Hippopotamidae are classified together with other even-toed ungulates in the order Artiodactyla. Other artiodactyls include camels, cattle, deer and pigs, although hippos are not closely related to those groups.
Five subspecies of hippopotamus have been described based on morphological differences in their skulls and geographical differences:
The Great Northern Hippopotamus or Nile Hippopotamus, H. a. amphibius - (nominal subspecies) whose habitat extended from Egypt, where they are now extinct, south along the Nile to Tanzania and Mozambique
East African hippopotamus H. a. kiboko - in Kenya in the African Great Lakes region and in Somalia in the Horn of Africa. They have wider nostrils and hollow interorbital regions
Cape hippopotamus or South African hippopotamus, H. a. capensis - from Zambia to South Africa. They have the most flattened skull among the subspecies.
West African hippopotamus or Chadian hippopotamus, H. a. tschadensis - throughout West Africa to, as the name suggests, Chad. They have a slightly shorter and wider face, with prominent orbits.
Angolan hippopotamus H. a. constrictus - in Angola, southern Democratic Republic of Congo and Namibia. They are noted for their deeper preorbital constriction Proposed subspecies have never been widely used or confirmed by field biologists; the morphological differences described were small enough to have resulted from simple variation in unrepresentative samples. Genetic analyzes tested the existence of three of these hypotheses