The Hippopotamus (Hippopotamus amphibius) is a large, fundamentally herbivorous artiodactyl mammal. It is a semi-aquatic animal that lives in rivers and lakes. Adult males are territorial, forming groups of 5 to 30 individuals, controlling a particular area of the river.
The Hippopotamus is easily recognisable by its barrel-shaped torso, enormous mouth and teeth, body with smooth almost hairless skin, its short and fat feet and its huge size. It is the third heaviest terrestrial animal. Despite its squat shape and short legs, it can reach great speed of up to 30 km/h over short distances. It is one of the most aggressive creatures in the world and is often considered to be the most ferocious animal in Africa. There are approximately 125 000 to 150 000 hippopotami in the whole of Sub-Saharan Africa. They are endangered due to the loss of their habitat and poaching to obtain their meat and ivory from their canine teeth.
Although it is not a strictly nocturnal animal, they are active at night. They spend the greater part of each day sleeping or rolling around in the water or in mud. Water serves to keep their body temperature low and stop their skin from drying out. Apart from eating, the majority of their lives (courtship, fighting amongst themselves, birth) take place in the water.
They leave the water at dusk and move inland to graze on areas of short grass, their principal food source. As with the majority of herbivores, they will consume other types of plants if given the chance. Although hippos rest together in the water, grazing is a solitary activity, and they are not territorial on land.
The majority of their defecations take place in water, creating deposits of organic matter in the riverbeds. Their average longevity is around 40 years of age in the wild and 50 years in captivity.
The males reach maturity at around seven years of age and the females reach sexual maturity at five or six years of age and have a period of gestation of eight months. The females can begin puberty at three or four years of age.
Mating takes place in the water, with the female submerged during the majority of the encounter. They are one of the few mammals to give birth underwater. The babies are also born under water, weighing between 25 and 45 kg. In general they give birth to one sole baby, although there have been cases of two. They swim underwater to suckle, although they also do so on land if the mother moves out of the water. Weaning takes place at between six and eight months after birth and the majority of babies are totally independent by the time they reach one year of age.