The pygmy hippopotamus is a medium-sized herbivorous mammal inhabiting the humid forests and swamps of West Africa. The pygmy hippopotamus is very rare and is severely threatened by hunting and habitat loss.

Pygmy hippopotamuses inhabit Cote d'Ivoire and Liberia in western Africa, with small populations in neighboring Guinea and Sierra Leone. The pygmy hippopotamus prefers swampland and dense, lowland tropical forests. They spend most of their time foraging for food and resting on land.

The pygmy hippopotamus is closely related to the common hippopotamus, but is better adapted to dense forest environments. Pygmies are much smaller in size – weighing just a fifth of their cousin's weight. The pygmy hippopotamus has a sleeker body and narrower mouth and spends much less time in the water than the common hippopotamus. While the pygmy hippopotamus is semi-aquatic, they have fewer webbed toes to aid them in moving effectively on land. Their eyes are on the sides of their head, instead of on the top, to see better in the forest.

The pygmy hippopotamus has smaller canines, or tusks, than the common hippo. Their bodies are long and barrel-shaped, covered in slate-gray skin that lightens towards the underside. The head of the pygmy hippopotamus is small in relation to the body, and the mouth is narrow.

The pygmy hippopotamus does not live in herds like the common hippopotamus. They are mostly solitary or live in pairs. Pygmy home ranges often overlap and they are known to tolerate others in their territory. Males, called bulls, have larger territories than females, called cows. They both mark their homes with their droppings. Pygmy hippopotamuses spend most of the day resting in cool mud or in the burrow of animals. Being mostly nocturnal, the pygmy hippopotamus forages in the forest at night.

Pygmies are herbivores, feeding on a variety of plants and fruits. While the common hippopotamus eats mostly grasses, the pygmy hippopotamus has a much more varied diet including ferns, shrubs, leaves, grasses and fruits that have fallen to the forest floor. Pygmy hippos have multi-chambered stomachs that function like hoofed land animals, but they are more closely related to whales. Like the common hippopotamus, they do not chew their cud.

Pygmy hippopotamuses follow well-trodden trails and established tunnels when foraging, and can run at incredible speeds to escape danger. Spending most of their time on land, pygmy hippos enter the water when threatened. Pygmy hippos are excellent swimmers and have strong muscular valves that close off their ears and nostrils when they are in water.

Pygmy hippos are shy and quiet. They communicate primarily through body language. If alarmed, they release their breath with a loud huff. Signs of submission include lying and urinating while wagging their tails.

Pygmy hippopotamuses cannot sweat and their skin easily dries up. A pink, oily substance is secreted through their skin glands to prevent sunburn. It also has anti-bacterial properties that keeps wounds clean and prevents infections in dirty water.

Pygmy hippopotamuses can be more aggressive during the breeding season. Males will bare their teeth and sometimes fight to win females. Gestation lasts for six to seven months. The mother pygmy hippopotamus gives birth to a single baby in a den or in the water. Pygmy hippopotamus babies are weaned by eight months old. They then join their mothers on foraging trips.

Being large animals, the pygmy hippopotamus has few natural predators. They are sometimes stalked by leopards. Calves are preyed on by large snakes and wildcats when the mother is foraging. Unlike their larger cousins, pygmy hippos prefer to flee from danger rather than fight. They also use lunging, rearing, head shaking and water scooping tactics to scare off predators.

The biggest threat to the pygmy hippopotamus is humans. Despite being protected by law, pygmy hippopotamuses are hunted for their meat and teeth. Their habitats are quickly being destroyed for animal agriculture. Their rivers are now polluted. Logging is illegal in many parts of their natural range, but continues to happen. There are fewer than 3,000 pygmy hippopotamuses left in the wild.

The pygmy hippopotamus is listed as Endangered in its natural environment and is severely at risk of extinction. The sub-species in Niger is Critically Endangered, and may already be extinct.