It is National Water Week and we are featuring a wonderful water mammal for MAD MAMMAL MONDAY! – the Hippopotamus Hippopotamus amphibius. The hippopotamus, or hippo for short, from the ancient Greek for "river horse" (?πποπ?ταμος), is a large, mostly herbivorous mammal in sub-Saharan Africa. It is one of only two extant species in the family Hippopotamidae (the other is the Pygmy Hippopotamus). After the elephant and rhinoceros, the hippopotamus is the third largest species of land mammal and the heaviest extant artiodactyl. Despite their physical resemblance to pigs and other terrestrial even-toed ungulates, their closest living relatives are the cetaceans (whales, porpoises, etc) from which they diverged about 55 million years ago. The common ancestor of whales and hippos split from other even-toed ungulates around 60 million years ago. The earliest known hippopotamus fossils, belonging to the genus Kenyapotamus in Africa, date to around 16 million years ago.
The hippopotamus is semi-aquatic, inhabiting rivers, lakes and mangrove swamps, where territorial bulls preside over a stretch of river and groups of 5 to 30 females and young. 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.
Hippos are recognizable by their barrel-shaped torso, enormous mouth and teeth, nearly hairless body, stubby legs and tremendous size. They are the third largest species of land mammal by weight (between 1½ and 3 tonnes); the only heavier species on average are the white and Indian rhinoceroses, typically 1½ to 3½ tonnes, and the elephants, typically weighing 3 to 9 tonnes. The hippopotamus is one of the largest quadrupeds and, despite its stocky shape and short legs, it can easily outrun a human. Hippos have been clocked at 30 km/h over short distances. The hippopotamus is one of the most aggressive creatures in the world and is regarded as one of the most dangerous animals in Africa. Nevertheless, they are still threatened by habitat loss and poaching for their meat and ivory canine teeth.
You can help us to map this amazing mammal's 21st century distribution by submitting your photos, along with the location details, to the MammalMAP Virtual Museum at vmus.adu.org.za. The photo featured here is from our MammalMAP Virtual Museum database, where it is Record 3185
Reference: Novak, R. M. 1999. Walker's Mammals of the World. 6th edition. Johns Hopkins University Press, Baltimore.