The hippopotamus, also known as the hippo, common hippopotamus, or river hippopotamus, is a large semiaquatic mammal and ungulate native to Sub-Saharan Africa. It is primarily herbivorous. It is one of just two living species in the Hippopotamidae family, with the pygmy hippopotamus being the other (Choeropsis liberiensis or Hexaprotodon liberiensis). The name is derived from the ancient Greek word o, which means “river horse.”

The hippopotamus is the third-largest land animal after elephants and rhinoceros and the biggest surviving artiodactyl (in the traditional, non-cladistic sense of the term, not including cetaceans). Despite their morphological resemblance to pigs and other even-toed ungulates on land, the Hippopotamidae’s closest extant relatives are cetaceans (whales, dolphins, porpoises, and so on), from whom they split around 55 million years ago. Hippos have barrel-shaped torsos, wide-opening mouths displaying enormous canine tusks, almost hairless bodies, columnar legs, and massive stature; males average 1,500 kg (3,310 lb) while females average 1,300 kg (2,870 lb). It can run at 30 km/h (19 mph) over short distances despite its stocky body and short legs.

Hippos live in rivers, lakes, and mangrove swamps, where territorial males rule over groups of five to thirty females and young hippos. They stay cool throughout the day by remaining in the water or mud; reproduction and birthing both take place in water. They come out to feed on grasslands at dusk. While hippos socialize in the water, grazing is a solitary pastime for them, and they are not territorial on land. Because of its very violent and unpredictable temperament, the hippo is one of the most deadly creatures on the planet. Poaching for their flesh and ivory canine teeth has put them in jeopardy because of habitat degradation and poaching.

According to the most recent theory of Hippopotamidae evolution, hippos and whales had a semiaquatic ancestor that split from other artiodactyls approximately 60 million years ago. Around 54 million years ago, this hypothetical ancestral group was divided into two branches.

One branch would develop into cetaceans, potentially starting around 52 million years ago with the protowhale Pakicetus and other early whale progenitors known as Archaeoceti, which later underwent aquatic adaption to become fully aquatic cetaceans. The anthracotheres, a vast family of four-legged creatures, evolved from the late Eocene anthracotheres, which resembled slender hippos with comparably tiny and narrow skulls. Except for the branch that developed into the Hippopotamidae, all branches of the anthracotheres died out during the Pliocene without leaving any offspring.

From the Eocene and Oligocene species Anthracotherium and Elomeryx through the Miocene species Merycopotamus and Libycosaurus and the very last anthracotheres in the Pliocene, a broad evolutionary lineage can be followed. Merycopotamus, Libycosaurus, and Hippopotamidae are all members of the same group, with Libycosaurus being closer to hippos. Their common progenitor existed during the Miocene epoch, around 20 million years ago. Hippopotamidae is so firmly embedded inside the Anthracotheriidae family.

Download Hippo Silhouette PNG vector transparent background images