The "river horse" is the translated Greek name for the hippopotamus so named because of his great attraction to the water. Hippos usually spend around 16 hours a day submerged in slow-moving rivers and lakes. They have very little protective hair, and the water helps keep their large bodies cool under the African sun. Also of help against extreme heat is their ability to "sweat blood," which is actually their secreting an oily red substance to serve as a coolant, sunscreen, and protection against germs often found in the murky waters.
Comical as it seems, the big-barreled, stubby-legged, clumsy-looking hippos are graceful swimmers and can easily hold their breath for up to five minutes while submerged. Because of their large size and since their eyes and nostrils are located high on their heads, they can see and breathe while walking or running along a lake floor or while just trifling in the shallows.
Staying in the water during the day helps the hippos conserve energy for their night-time travel on land. At sunset, they leave the water, wandering a long way in search of vegetation. If sensing danger, they'll run back toward the water where they have an advantage over enemies. It is interesting to note that on land they can run about 19 miles an hour for short distances.
Though they do cover miles of grazing land to satisfy their hunger, they eat relatively little for their size....about 150 pounds of grass per night.
They are territorial in the water, but that is not the case when it comes to land. On land, it's share and share alike.
Today there are only two species (Common Hippo and the Pygmy) of Hippos left in the world, and both are found wild in Africa.
In competition with the white rhino as second largest land animal, a hippo in weighing from 5,000 to 8,000 lbs, is often a main attraction at a zoo. An adult hippo is typically 13-ft. long and 5-ft. tall.
Contrary to their aggressive nature, hippos often appear peaceful and quiet when caged at the zoo. Most of them in zoos today have been born in captivity. They are rather expensive to keep, requiring a lot of land to walk on and deep water to swim in. They can live for as long as 45 to 50 years.
With their natural habitat dwindling and because they are often killed for sport, for their fatty meat, and for their ivory teeth, they are now an at-risk species, mostly confined to protected areas.