Hippopotamuses (often called hippos) have huge, round bodies that sit atop short legs. Males weigh 600 to 4,000 pounds (270 to 1,800 kilograms) and measure 60 to 106 inches (152 to 270 centimeters). Females weigh between 500 and 3,000 pounds (230 to 1,500 kilograms) and measure 58 to 106 inches (150 to 270 centimeters). Hippos have four toes on each foot with slight webbing between them. Though the skin looks hairless, there is a sparse covering of fine hairs over the entire body. The hippo has no sweat glands, but it does have skin glands that secrete a fluid. Experts believe this liquid acts as a sunscreen as well as an antiseptic (germ-killer). Hippos vary in color from slate brown to mud brown, and in certain lighting give off shades of purple.
The head is big with a wide mouth. The canines (pair of pointed teeth located in the front of the mouth on both jaws) and incisors (four front teeth, situated between the canines on both jaws) look like tusks and grow continuously throughout the hippo’s lifetime.
The nostrils, eyes, and ears are located high on the face, which allows the animal to remain submerged for a long time with very little of its body showing. The hippo has a multichambered stomach, which allows for fermentation (breakdown) of food for more efficient digestion.
Hippos live throughout Africa.
Common hippos like deep freshwater locations during the day, but venture out of the water at night to graze. The pygmy hippo lives in the forest and spends its day near or in water. Water is important to the hippo because if it can’t submerge itself, its skin will crack from dehydration and overheating.
Hippos are vegetarians and eat mainly grasses, though the pygmy hippo also feeds on fruits and ferns. All hippos eat by nipping off the vegetation with their powerful lips. They eat about 88 pounds (40 kilograms) of grasses each night.
BEHAVIOR AND REPRODUCTION
Hippos do not feed in groups (with the exception of motheroffspring) because they are largely immune to predators and so are able to forage without fear of attack. Male hippos are in charge of home ranges, which they keep for four years in rivers and at least eight years in lakes. There have been reports of hippos retaining the same range for the entire span of their lives, twenty to thirty years. Herds average ten to fifteen in size, but vary from two to fifty. Nonbreeding males, though tolerated, are often the victims of territorial fights with breeding adult males. These “bachelor” males tend to live in herds of their own or alone.
Though large, hippos can run 18 miles per hour (30 kilometers per hour) when threatened, and they are able climbers. They are not able to jump and won’t even attempt it.
Both hippo species mate and give birth in the water, but the pygmy hippo also mates and gives birth on land. Pregnancy lasts 227 to 240 days and results in the birth of a single calf. Calves nurse (drink mother’s milk) underwater. Male hippos begin breeding between the ages of six and fourteen, whereas females are ready to breed between the ages of seven and fifteen. Calves are usually born in the rainy months.
Healthy adult hippos do not fall prey very often, but young hippos and old or sick hippos are in danger of being killed by lions, hyenas, and crocodiles.
HIPPOPOTAMUSES AND PEOPLE
Hippos are valued as a food source in Africa. Their teeth provide a high-quality ivory, and their hides are also of value. Hippos are considered one of the most dangerous animals in Africa because they have no fear of humans and are aggressive. They also raid and damage agricultural crops.
The pygmy hippo is listed as Vulnerable, facing a high risk of extinction, dying out, by the IUCN, and two other species are Extinct. The common hippo has a healthy population, but is vulnerable to extinction in West Africa. The primary threat to hippos is loss of habitat.