Hippos rule the rivers and lakes of Africa. Congregating in herds of up to 100 individuals, they spend as much as 16 hours a day submerged in water, resting and sleeping. They can hold their breath for up to five minutes. Hippos do not have true sweat glands, so water keeps their skin cool and prevents dehydration. Their pores secrete a thick red fluid sometimes called “sweat blood” that acts like a sunscreen to protect their thick skin from sunburn and infection. With eyes, ears, and nostrils on the top of their heads, hippos are able to hear, see, and breathe while most of their body remains submerged. Underwater, the ears and nostrils close. Their massive jaws can open 150 degrees. Hippos cannot swim, so they glide by walking along the river bottom.
Hippo gestation lasts about 13 months. Calves are often born underwater, rump first, and immediately paddle to the surface to breathe. Calves nurse for 6 to 8 months, often underwater, and remain with their mothers for about five years. The hippopotamus is considered one of Africa’s most dangerous animals. Most attacks take place in water. Males (bulls) actively defend their territory in the water and along the riverbank. Dominant males will fight each other with urine and feces, sometimes flapping their tails like windshield wipers in a move called “dung-showering.” Their feces provide nutrition for many species, from invertebrates to fish. Females will fiercely protect their young from predators. Hippos come out of the water at night to feed on grasses. On land they can run up to 25 mph. By moving from water to shore, they create pathways that allow the rivers to flow freely. Pigs were once thought be the hippo’s closest relative, however DNA evidence now shows hippos are more closely related to dolphins and whales, with whom they shared a common ancestor 50 million years ago.
Rivers, lakes, and swamps of sub-Saharan Africa. Hippos need water sufficient to allow them to totally submerge.
Hippos are herbivores and graze on land, preferring short grass. They will graze up to six miles inland eating up to 80 pounds of grass per day. They require less food than many other hoofed animals because of their sedentary lifestyle.
Males grow to 10 to 16 feet long and weigh 6,000 pounds or more. Females are smaller, weighing around 3,000 pounds. Hippos typically live 40 to 50 years.