Hippopotamus

The hippopotamus (Hippopotamus amphibius) is a large, semi-aquatic mammal that lives in rivers, lakes, and other bodies of water in sub-Saharan Africa. It is one of the heaviest land animals, with a barrel-shaped body, short legs, and a large head with a broad mouth.

The name 'hippopotamus' derives from ancient Greek and means 'river horse'. However, the hippopotamus is not closely related to horses; genetic studies have shown that its closest living relatives are cetaceans such as whales and dolphins.

Body structure

The hippopotamus has smooth, nearly hairless skin, typically dark brown or grey in colour. The skin secretes a reddish fluid that protects against sunburn and bacteria—which some people have interpreted as 'blood sweat', though it is not blood. The lower canine teeth are large and prominent, and can grow to considerable lengths.

Behaviour and ecology

During the day, the hippopotamus stays in water to avoid direct sunlight and keep its skin moist. At night it leaves the water to graze on grass. It lives in groups, each typically led by a dominant male that defends a section of river.

The hippopotamus is highly aggressive when its territory is invaded, especially if a nursing mother and young are present. Conflict between humans and hippopotamuses therefore occurs in areas where settlements and water sources overlap.

Conservation status

Hippopotamus populations have declined in parts of Africa, primarily due to poaching for teeth and meat and habitat loss from land-use changes that reduce water availability and grazing areas. Conservation authorities rate the species as vulnerable.