General info
The hippopotamus (Hippopotamus amphibius) or hippo (Greek: ἱπποπόταμος, hippopotamos, from ἵππος, hippos, "horse", and ποταμός, potamos, "river") is a large, mostly plant-eating mammal in sub-Saharan Africa, and one of only two extant species in the family Hippopotamidae (the other is the Pygmy Hippopotamus). The hippopotamus is the heaviest extant artiodactyl, despite being considerably shorter than the giraffe.

This compound word is the wrong way round for Greek and correctly would mean "horse-river". The more common Ancient Greek term was ἱππος ποταμου "horse of river",

The hippopotamus is semi-aquatic, inhabiting rivers and lakes where territorial bulls preside over a stretch of river and groups of 5 to 30 females and young. During the day they remain cool by staying in the water or mud; reproduction and childbirth both occur in water. They emerge at dusk to graze on grass. While hippopotamuses rest near each other in the water, grazing is a solitary activity and hippos are not territorial on land.

Despite their physical resemblance to pigs and other terrestrial even-toed ungulates, their closest living relatives are cetaceans (whales, porpoises, etc.) from which they diverged about 55 million years ago. The common ancestor of whales and hippos split from other even-toed ungulates around 60 million years ago. The earliest known hippopotamus fossils, belonging to the genus Kenyapotamus in Africa, date to around 16 million years ago.


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The most recent theory of the origins of Hippopotamidae suggests that hippos and whales shared a common semi-aquatic ancestor that branched off from other artiodactyls around 60 million years ago.

he sale of hippo meat is illegal

Hippos spend most of their days wallowing in the water or the mud, with the other members of their pod. The water serves to keep their body temperature down, and to keep their skin from drying out. With the exception of eating, most of hippopotamuses' lives—from childbirth, fighting with other hippos, and reproduction—occur in the water.

Hippos leave the water at dusk and travel inland, sometimes up to 8 kilometers (5 mi), to graze on short grass, their main source of food.

Adult hippos cannot swim and are not buoyant. When in deep water, they usually propel themselves by leaps, pushing off from the bottom.

They move at speeds up to 8 km/h (5 mph) in water. However, young hippos are buoyant and more often move by swimming—ropelling themselves with kicks of their hind legs.

Adult hippos typically resurface to breathe every 3–5 minutes. The young have to breathe every two to three minutes.

The process of surfacing and breathing is automatic, and even a hippo sleeping underwater will rise and breathe without waking.

A hippo closes its nostrils when it submerges.

Hippos are very aggressive towards humans and are often considered one of the most dangerous large animals in Africa. Hippos attack humans and boats.

To mark territory, hippos spin their tails while defecating to distribute their excrement over the greatest possible area.
Hippos are retromingent, likely for the same reason.

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