Hippopotamus (Hippopotamus amphibius)

Mammal Semi-aquatic Herbivore

Overview

The common hippopotamus (Hippopotamus amphibius) is a large, semi-aquatic mammal of sub-Saharan Africa and one of the heaviest land animals alive. Hippos spend much of the day in rivers, lakes, and wetlands and emerge after dark to graze on land, making them a defining presence of Africa's freshwater systems.

Despite a bulky, slow-looking build, hippos are powerful and can move quickly over short distances both in water and on land. They are strongly territorial in water, and their grazing and dung deposition play an important role in moving nutrients between land and aquatic ecosystems.

Conservation note: the common hippopotamus has been assessed as Vulnerable on the IUCN Red List in recent assessments, with habitat loss and unregulated hunting among the main pressures. Always verify current status at iucnredlist.org before relying on it. The hippo family also includes the much smaller, separately assessed pygmy hippopotamus (Choeropsis liberiensis) of West Africa.

Classification

Hippos belong to the even-toed ungulates (Artiodactyla). Molecular and fossil evidence places cetaceans (whales and dolphins) as their closest living relatives — a relationship that surprises many readers given the hippo's superficially pig-like appearance.

Habitat & Range

Common hippos occur across sub-Saharan Africa wherever there is permanent water bordered by grazing land. They favour slow rivers, lakes, swamps, and seasonal pools deep enough to submerge in. Strongholds include parts of East Africa's Rift Valley lakes and rivers and the wetlands of southern Africa.

Suitable habitat must combine deep water for daytime refuge with accessible grassland for night-time grazing, so hippo distribution closely tracks the availability of both.

Diet & Feeding

Hippos are herbivores that feed mainly on grasses. They leave the water at dusk and may travel several kilometres along established paths to grazing areas, cropping short grasses with their broad lips before returning to water by dawn. Their enormous canine and incisor teeth are used for fighting and display rather than feeding.

Behavior & Social Life

Hippos are social in water, gathering in groups — often called pods or schools — that can range from a handful of animals to several dozen, typically led by a dominant male defending a stretch of water. Much of their communication is vocal, including loud grunts and bellows, some of which carry both above and below the surface.

Territorial disputes between males can be intense, involving open-mouthed threat displays and clashes with their large tusk-like teeth. Females are highly protective of calves, which can nurse and even suckle underwater.

Appearance & Recognition

Hippos have a barrel-shaped body, short legs, and a massive head with eyes, ears, and nostrils set high so the animal can see, hear, and breathe while mostly submerged. The skin is thick and nearly hairless, grey to brownish, and secretes a reddish substance sometimes called “blood sweat” that helps protect against sun and infection.

At a distance, hippos are recognised by the rows of eyes and nostrils breaking the surface of a river, their bulk when hauled out on banks, and the explosive open-mouthed gape used in threat displays. The pygmy hippopotamus is far smaller, rounder, and forest-dwelling rather than living in large open-water pods.

Human Interaction & Conservation

Hippos can come into serious conflict with people, both through their defence of waterways and through crop feeding near settlements. They are also affected by habitat loss, water diversion, and hunting for meat and ivory-like canine teeth. Effective conservation depends on protecting freshwater habitats and managing human–wildlife conflict around them.

More photos of the hippopotamus