Common Hippopotamus

The common hippopotamus (Hippopotamus amphibius) has a barrel-shaped torso, short legs, a broad head, long snout, and enlarged canines and incisors that are especially prominent in males. The eyes, ears, and nostrils at the top of its head allow the hippo to breath and monitor its environment while most of its body is underwater. The hippos’ smooth, almost hairless hide is brown to grey-purple with pink underparts, and is populated with glands that secrete a reddish, antiseptic fluid that also protects the skin from drying and sunburn.

Though “hippopotamus” is ancient Greek for “river horse,” the animal was once thought to have a common ancestry with pigs. More recent studies indicate that its closest living relatives are whales and dolphins.

The hippo is third largest land mammal after elephants and white rhinos. Males, which grow throughout their lifetimes, can measure 3.5 metres from head to base of tail and weigh more than 2000 kilogrammes. Females are smaller.

Distribution of hippopotamus

The hippopotamus was once broadly distributed in Africa, from Egypt to the Cape, wherever there was permanent water and nearby grasslands. The hippos’ current range is limited to sub-Saharan regions, with the largest populations in East Africa. Hippos are most common in protected areas. They have been eliminated or are rapidly disappearing over the bulk of their historic range.

True to their amphibious nature, hippos spend most of the daylight hours resting in shallow water or muddy wallows, where they are highly gregarious and vocal. At dusk and night, the hippopotamus is a solitary grazer. Walking slowly and silently on land, a hippo can crop 60 kilogrammes of grass in a single night entirely by grabbing and pulling mouthfuls of grass with its lips. Its formidable canines and incisors are used exclusively for display and fighting.

Hippo herds typically number ten to fifteen animals and include females, their young offspring, a dominant male, and sometimes a few non-breeding males. However, some herds can be much larger, as with the more than 150 animals that gather at Serengeti’s Retina Hippo Pool, a deep pool of water formed at the convergence of the Seronera and Orangi rivers.

Hippos are famous for their aggression. Bulls occupy narrow strips of land and nearby shore, tolerating submissive males, but defending against would-be competitors for mates. Conflicts are frequent, with the advantage usually going to the heavier bull. Though young hippos might be prey for lions or crocodiles, the major hazards for an adult are humans and other hippos.

Female hippos give birth to a single calf, usually underwater. Births are spaced about two years apart, with one female and up to four offspring serving as a stable social unit within the larger herd. Males mature within five to about seven years, and females within seven to fifteen. Hippos can live up to 50 years in captivity, but considerably fewer years in the wild.

The hippo population in Serengeti Park is stable. However, outside of protected areas such as Serengeti, hippos are threatened by habitat fragmentation, loss of access to grazing land or water, hunting for meat, and poaching for their ivory canines. These problems are particularly severe in areas beset by civil conflict. In many regions, the hippos’ reputation for raiding farm crops and unprovoked attacks on humans leads to illicit as well as legally sanctioned killing.