Hippos have grayish skin with short, fine hairs that sparsely cover their bodies. Hippos have specialized pores that ooze an oily pink substance that protects their sensitive skin from water loss and sunburn. Early explorers thought that hippos sweat blood, but what they were seeing was really this secretion.

Hippos have enlarged incisors and long, curved lower canines that grow continuously throughout the animal's life. These tusks are kept extremely sharp by rubbing against the shorter upper canines.  

Wild hippos are known to live throughout much of sub-Saharan Africa wherever acceptable habitat is available. The largest populations of hippopotamus can be found in Central Africa and along the Nile River Valley in East Africa. Hippos are found in rivers and lakes that are deep enough for the animals to submerge, and that have nearby grasslands for grazing.
 

In captivity and in the wild, hippos are long-lived animals that mature slowly and have calves every other year. Hippos generally live into their 30's, although older individuals are not uncommon.

Hippos in the wild live in loose groups consisting of one territorial male and several females. The bull will fight off competition from other male hippos in order to defend a section of the river or lake and keep all the females that enter his territory for himself.

A hippo's pregnancy lasts eight months. Breeding usually takes place so the calf will be born during the height of the rainy season. The calf is born in the water, can weigh over 100 pounds and is nursed completely underwater. By the time the calf reaches a year it will weigh approximately 500 pounds.

Calves and their mothers form life-long bonds. Male hippos reach the age of sexual maturity anywhere between six and 14 years old, although only older, stronger males can defend a territory and breed. Females begin breeding between seven and 15 years of age.
 

 

Hippos spend most of their time in the water with only their eyes and nostrils exposed. When underwater, they can hold their breath for as long as six minutes before coming up for air. Although hippos can swim, they prefer to walk along the river bottom and are surprisingly graceful.

Hippos, considered the most dangerous animal in Africa, are extremely territorial. In their social groups, hippo males will search for the best territory along the shoreline and defend it vehemently. To protect their young, females group together to form their own nursery herd. Hippos of both sexes have been known to attack and flip boats that trespass in a male's territory or come too close to the young, often with fatal results.