Hippopotamuses secrete a natural red-colored sunscreen substance to protect their skin from the sun.
Semiaquatic Hippopotamus Related to Whales
A large, mostly plant-eating mammal, the hippopotamus is found in rivers and lakes throughout Africa. The hippo is semiaquatic and thought to be more closely related to whales than to other hoofed animals. Adults can measure up to 11 feet long, stand 5 feet tall and weigh up to 1.5 tons. It has been known to live up to 45 years in the wild.
The hippopotamus is characterized by its stout body, stubby legs and large, bulbous head. The head features jaws that open up to 150 degrees with long tusk-like teeth and a wide nose covered in sensitive bristles. The placement of ears, eyes and nostrils on the top of the skull allows it to stay nearly submerged in water all day, yet breathe easily and remain receptive to its surroundings. At night, the hippopotamus moves inland to graze on short grasslands. Despite their considerable bulk, hippopotamuses are graceful underwater swimmers and can run faster than humans on land, at an estimated 18-30 miles per hour.
The hippopotamus is one of the few mammals to give birth underwater. At birth, calves weigh 60 to100 pounds and must swim to the surface to catch their first breath. For the next five years, they remain with their mothers, who fiercely protect them from lion, crocodile and adult male hippopotamus attacks. Hippopotamuses form large social groups called rafts, in which there is one male and many females with their calves. There are about 15 members in a group though, in the dry season, up to 200 hippopotamuses can be forced to congregate near limited water pools.
Adult hippos are extremely hostile towards crocodiles, which share the same habitat, and are very dangerous when in the presence of humans. Hippopotamus populations across Africa are significantly threatened by habitat loss and unregulated hunting. The IUCN lists hippos as Vulnerable, which is one step removed from Endangered.