The common hippopotamus (also called the hippo) once ranged over much of Europe, the British Isles and Africa, but it is now restricted to a portion of the African continent, north of Zululand. As civilization advances and more and more areas are settled, the hippo becomes a problem because of the damage it does to crops. As a result, it is mercilessly hunted and its numbers have been greatly reduced.
The hippopotamus is the second largest land-living animal, by weight, in the world. The average specimen weighs about four tons; some individuals, as much as five. The massive head alone may weigh a ton. The animal is from twelve to fourteen feet in length and stands about four and a half feet at the shoulder. The huge, barrel-shaped body is supported by short, pillar-like legs. The hippo can open its huge mouth wider than any other animal, except the whales. The skin is very thick over most parts of the body, reaching a maximum thickness of two inches over some of the upper areas.
The internal organs of the hippo are of equally amazing dimensions. The stomach may reach a length of over ten feet. To fill this vast cavern, the animal may consume five or six bushels of vegetation in the course of a single day. The hippo's great appetite has proved useful to mankind, because it impels the animal to feed voraciously on river growths that would otherwise choke the streams.
Hippos live in herds of twenty to thirty individuals. Each herd keeps to the river most of the day, moving up and down the stream for considerable distances in search of food. Hippos can remain under water for as long as thirty minutes, if necessary; the normal interval, however, is from five to ten minutes. The animals can float on the surface or sink to the bottom at will. Nostrils and ears can be hermetically sealed, voluntarily, as the animals sink to the bottom of the river. Hippos are excellent swimmers; they can also walk along the river bottom at quite surprising speed — eight miles an hour, according to certain authorities.
At night, the members of the herd occasionally leave the river for short periods of time to feed on vegetation along river banks. A hippo will never go too far, and it will return before morning along the same path, following its own scent back to the river. Should a heavy rain wash away the scent, the animal will be lost. On land, the animal can walk about as fast as a man and it can even gallop after a fashion. While it is on land, special skin glands pour forth an oily, reddish liquid that prevents the skin from drying out. The fact that this liquid resembles blood in appearance has given rise to the perfectly absurd belief that the hippopotamus sweats blood.
Hippos mate once a year. The bulls fight savagely at mating time, and their battles sometimes have a fatal outcome. The gestation period is about nine months; the female gives birth to a single calf. Even a baby hippo weighs a hundred pounds or so at birth and its weight increases rapidly. Usually it is suckled in the water. It travels from one place to another by riding on its mother's back.
The pigmy hippopotamus is found in Liberia and Sierra Leone, in West Africa. It stands only about three feet high at the shoulder, is about six feet long and weighs a mere four hundred pounds. Though far "less bulky than the common hippopotamus, the pigmy resembles the larger animal in both appearance and habits.
