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Catiana
November 20th, 2007, 01:22 PM
Hippopotamus


Physical Characteristics
The hippopotamus, whose hide alone can weigh half a ton, is the third-largest living land mammal, after elephants and white rhinos. It was considered a female deity of pregnancy in ancient Egypt, but in modern times has been wiped out of that country because of the damage it inflicts on crops. The hippo continues to thrive in other parts of Africa.

Hippos are the third-largest living land mammal, after elephants and white rhinos. A hippo’s foot has four webbed toes which splay out to distribute weight evenly and therefore adequately support it on land. The grayish body has very thick skin which is virtually hairless. The hippo has neither sweat nor sebaceous glands, relying on water or mud to keep cool. It does, however, secrete a viscous red fluid which protects the animal’s skin against the sun and is possibly a healing agent. The hippo’s flat, paddle-like tail is used to spread excrement, which marks territory borders and indicates status of an individual.

Habitat
Two hippo species are found in Africa. The large hippo, found in East Africa, occurs south of the Sahara. This social, group-living mammal is so numerous in some areas that "cropping" schemes are used to control populations that have become larger than the habitat can sustain. The other, much smaller (440 to 605 pounds) species of hippo is the pygmy hippopotamus (Choeropsis liberiensis). Limited to very restricted ranges in West Africa, it is a shy, solitary forest dweller, and now rare.

Behavior
Hippos have a flexible social system defined by hierarchy and by food and water conditions. Usually they are found in mixed groups of about 15 individuals held by a territorial bull, but in periods of drought large numbers are forced to congregate near limited pools of water. This overcrowding disrupts the hierarchical system, resulting in even higher levels of aggression, with the oldest and strongest males most dominant. Old scars and fresh, deep wounds are signs of daily fights that are accompanied by many vocalizations.

A single young is born either on land or in shallow water. In water, the mother helps the newborn to the surface, later teaching it to swim. Newly born hippos are relatively small, weighing from 55 to 120 pounds, and are protected by their mothers, not only from crocodiles and lions but from male hippos that, oddly enough, do not bother them on land but attack them in water.

Young hippos can only stay under water for about half a minute, but adults can stay submerged up to six minutes. Young hippos can suckle under water by taking a deep breath, closing their nostrils and ears and wrapping their tongue tightly around the teat to suck. This procedure must be instinctive, because newborns suckle the same way on land. A young hippo begins to eat grass at 3 weeks, but its mother continues to suckle it for about a year. Newborns often climb on their mothers' backs to rest.

Diet
Hippos are surprisingly agile and often traverse steep banks each night to graze on grass. They exit and enter the water at the same spots and graze for four to five hours, covering one or two miles, with extended forays of up to five miles. Their modest appetites are due to their sedentary life, which does not require high outputs of energy.

Predators and Threats
The hippo once ranged from the Nile delta to the Cape. Now it is mostly confined to protected areas. Hundreds of hippos are shot each year in “controlled management” schemes, despite the fact that hippos are easily deterred by ditches or low fences. It is more likely that the popularity of hippo meat is the reason for this strategy. The fat and ivory tusks of the hippo, as well as the land on which it grazes, are also of value to humans.

Did You Know?
The name hippopotamus comes from the Greek "hippos," meaning horse, these animals were once called "river horses." But the hippo is more closely related to the pig than the horse.

Hippos spend most of their day in water close to shore lying on their bellies. In areas undisturbed by people, hippos lie on the shore in the morning sun.