It may be said to be amphibious in its nature; for it spends most of its time in the water, but frequents the land in search of food, which consists of various plants that grow in shallow waters, or that may be found along the shores of lakes and margins of rivers.
The animal is of no little service in keeping the current of sluggish streams free from the luxuriant growth of tropical vegetation. Were it not that the creature browses upon this growth, the streams would soon become choked, and their beds would become dismal swamps, of the kind common to Africa.
When in want of food from the land these animals leave the water at night to feed along the banks, or to make havoc in the cultivated fields, as they trample down and devour the crops. As they always travel in herds of twenty or thirty, it is no small misfortune for a herd to visit any section under cultivation. It is little wonder, then, that war has been waged against them, until in some regions they have ceased to exist. Doubtless this accounts for the fact that they are no longer found in the districts of Lower Egypt, though found to quite a large extent farther up the Nile.
The common hippopotamus is one of the largest of all living animals. The bulk of its body is very nearly as great as that of the elephant. Its legs, being very short, give it a most ungainly gait as it tries to support its great bulk in walking. Unlike the elephant, it is not a very tall animal, its height rarely reaching above five feet.
The hippopotamus, like the elephant, belongs to the family of thick-skinned animals. The skin on its back and sides is more than two inches thick. The skin is described as dark brown in color, and almost destitute of hair. It is kept constantly lubricated by means of the numerous pores, which exude a thick, oily fluid in great abundance.
The neck of the hippopotamus is short and thick, while the head is very large. Its small eyes and ears are placed so high on the head that, in spite of the shortness of the neck, they can easily be kept above the surface of any body of water in which the animal may lie almost hidden from view. The muzzle is very large, with a rounded, swollen surface. The great ugly nostrils and huge lips, which conceal the large front teeth, give the animal a most unattractive and repulsive expression.
It can cut down grass or corn with its large front teeth as well as if it were done with a scythe. So great is the strength of the teeth that stems of considerable thickness can be easily and neatly bitten through like a blade of grass.
The legs of the hippopotamus are, as we have seen, short and thick. Its feet are divided into four toes of nearly equal size, each covered with a horny hoof. Its short tail and the shape of its skull remind one of the pig family.
It breathes very slowly, and hence is enabled to remain under water for a long time, coming to the surface only at intervals for air. It can swim and dive easily, and often amuses itself by walking along the bottom of the river or lake with its body completely under water.
It is very active and playful in the water, but it soon learns to hide away from man. If it cannot conceal itself among the reeds, it dives under water and remains there hidden from sight, raising only its nose above water, as it finds it necessary to take another breath. It is no unfrequent thing to see the mother hippopotamus swimming across a stream with her little one clinging to her back.