Common Hippopotamus

Hippo Photo
Hippos are very territorial and use their long canine teeth as weapons. These teeth contain ivory, which puts them at greater risk of poaching.
Julie Larsen Maher ©WCS
Hippo Photo
Zambia’s Luangwa River in southeastern Africa currently supports the continent’s largest population of hippos.
Julie Larsen Maher ©WCS

In the ancient Greek language, hippopotamus means “river horse.” Formidable at 1.5 to 3 tons and armed with large canine teeth, the hippo could be the most dangerous animal in Africa. On land, this large mammal can run up to 14 miles an hour over short distances. In water, it can capsize fishing boats that invade its territory.

Hippos are semi-aquatic, social herbivores that inhabit slow-moving rivers and lakes. Territorial bulls preside over groups of as many as 30 females and their young. Despite its physical resemblance to a pig, the hippo’s closest living relatives are cetaceans, such as whales and porpoises.

The hippo’s eyes, ears, and nostrils are on top of its head, making it possible for the animal to hear, see, and breathe while keeping most of its body submerged underwater. With a clear membrane protecting its eyes and the ability to close its nostrils, a hippo can hold its breath for five minutes or longer. Adult hippos, however, are not buoyant and usually move about by walking or running along the bottoms of rivers and lakes. The animals go about much of their regular business in the water, mating and giving birth there, and generally keeping cool during the heat of the day. At dusk, they emerge to graze on grass. Keeping water channels and land well grazed, hippos have a great impact on the life cycles within their habitats. Even their dung, which is rich in nutrients, helps to nourish aquatic microorganisms and fish.

Fast Facts

Scientific NameHippopotamus amphibious
  • There are two species of hippos: the common, which occurs across much of Africa, and the endangered pygmy hippo, Hexaprotodon liberiensis. This hippo is like a miniature version of its larger cousin and spends more of its time on land. The pygmy hippo is restricted to the dwindling forests of western Africa.
  • The common hippo is Africa’s third largest land mammal after elephants and white rhinos.
  • Hippos are hostile to crocodiles, which frequently live in the same pools and rivers and prey on their calves. Hippos have also been known to attack humans, and even boats. When feeling threatened, they open their huge mouths and bellow. Females are fiercely protective of their young, which are born after an eight-month gestation.
  • Hippos use their long canine teeth as weapons. The hides of many adult males are covered with "battle scars" incurred during fights.
  • A red substance that hippos secrete from their skin has led to the myth that they sweat blood. The secretion is neither sweat nor blood but rather a moistening and anti-sunburn layer of mucus. This mucus might have antibacterial properties.


Hippo habitat has greatly diminished over the past 200 years, and hunting has further reduced their numbers. There are an estimated 125,000 to 150,000 common hippos. This represents a decline of as much as 20 percent during just the last decade. Particularly drastic declines (estimated at 95 percent) have occurred in Virunga National Park in the Democratic Republic of Congo, primarily due to poaching during this country’s civil war. Hunters kill hippos for meat and for the ivory contained in their massive teeth and tusks. These may serve as unfortunate replacements for increasingly scarce elephant ivory.

A conservation crisis is at hand for pygmy hippos, with only 2,000 to 3,000 remaining in the dwindling forests of western African countries, such as Liberia, Côte d’Ivoire, and Sierra Leone.

WCS Responds

Zambia’s Luangwa River in southeastern Africa currently supports the continent’s largest population of hippos. WCS has been working in the Luangwa Valley region for more than 25 years. As part of its efforts to safeguard the wild lands there and to provide incentives to the local people for conservation, WCS has helped negotiate human-hippo conflicts, which includes farm damage. WCS has been developing alternative crops, educating residents about ways to coexist with hippos, and promoting tourism in the region. WCS is also increasing its work in the Greater Virunga landscape—which spans Uganda, Rwanda, and the Democratic Republic of Congo—to protect its remaining hippos and an array of other threatened species.
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