Habitat. Hippos live in sub-Saharan Africa. They can only survive in areas with abundant water, though, so they live in areas with rivers and lakes. Hippos are amphibious animals and spend up to 16 hours per day in the water, according to National Geographic. The water keeps them cool in the African heat. They spend all day in the water and then hunt for food at night.
http://www.livescience.com/27339-hippos.html
Meanwhile, the anthracotheres died out (presumably slowly and lazily), leaving only one descendant: the hippo. In fact, scientists have argued that dolphins and whales should be combined into the order Artiodactyla, which contains not only hippos, but also deer, camels, cows, pigs and giraffes. Yet, if you came across a whale humping a camel, you'd think it was weird. But hey, we're not here to judge.
http://www.cracked.com/article_19264_5-species-you-wont-believe-are-related.html
Hippos are very rotund animals and are the third largest living land mammals, after elephants and white rhinos, according to Animal Planet. They grow to 10.8 to 16.5 feet (3.3 to 5 meters) long and up to 5.2 feet (1.6 m) tall from hooves to shoulders.
http://www.livescience.com/27339-hippos.html
The name comes from the ancient Greek for river horse (ἱπποπόταμος). After the elephant and rhinoceros, the common hippopotamus is the third-largest type of land mammal and the heaviest extant artiodactyl.
https://en.wikipedia.org/wiki/Hippopotamus
The word hippopotamus is derived from the ancient Greek ἱπποπόταμος, hippopotamos, from ἵππος, hippos, horse, and ποταμός, potamos, river, meaning horse of the river.
https://en.wikipedia.org/wiki/Hippopotamus
Dolphins and Hippos. The cetaceans (whales and dolphins) are some of the most beloved and respected animals in the world. Whales are the gentle giants of the sea, while dolphins are the fun-loving clowns who show up in a lot of female tattoos, despite the fact that they maybe also are serial killers. Now we all know that these regal creatures are mammals, so they're not as related to fish as you might otherwise think.
http://www.cracked.com/article_19264_5-species-you-wont-believe-are-related.html
Watch a hippo, on land or in the water, and you’ll soon discover that this roly-poly is one of the animal world’s great characters. It is the most rotund land mammal and spends its daytime hours in lakes, pools, mudholes, or in the preferred moving waters of rivers.
http://animals.sandiegozoo.org/animals/hippo
The hippopotamus is a highly aggressive and unpredictable animal and is ranked among the most dangerous animals in Africa.
https://en.wikipedia.org/wiki/Hippopotamus
The name “hippopotamus” comes from a Greek word meaning “water horse” or “river horse.” But hippos are not related to horses at all—in fact, their closest living relatives may be pigs or whales and dolphins! There are two species of hippopotamus: the river, or common, hippo and the much smaller pygmy hippo. Hippos are definitely adapted for life in the water and are found living in slow-moving rivers and lakes in Africa.
http://animals.sandiegozoo.org/animals/hippo
The hippo is similar in size to the white rhinoceros. Hippos can store two days' worth of grass in their stomachs and can go up to three weeks without eating. An adult hippo can hold its breath underwater for up to 30 minutes. In African rivers, hippos look like floating islands, with birds fishing from their backs.
http://animals.sandiegozoo.org/animals/hippo
what mammal is related to hippos?
Pigs, whales and dolphins are mammal that related to hippos. Pigs, whales and dolphins are mammals related to hippos.  