Hippopotamuses: Hippopotamidae

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HIPPOPOTAMUSES: Hippopotamidae

COMMON HIPPOPOTAMUS (Hippopotamus amphibius): SPECIES ACCOUNTS
PYGMY HIPPOPOTAMUS (Hexaprotodon liberiensis): SPECIES ACCOUNTS

PHYSICAL CHARACTERISTICS

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 multi-chambered stomach, which allows for fermentation (breakdown) of food for more efficient digestion.

GEOGRAPHIC RANGE

Hippos live throughout Africa.

HABITAT

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.

DIET

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 mother-offspring) 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.

HIPPO TRIVIA

The common hippo is the second largest living land animal, surpassed only by the Indian rhinoceros.
The word "hippopotamus" means "river horse."
Unlike other mammals, it is the female hippo who chooses a mate. If a male hippo does not treat her with respect upon approach, she will not choose him!
Mother hippos punish their babies by rolling them over with the mothers' heads or even slashing them with mothers' tusk-like teeth.
When hippos fight, their goal is to break the front leg of their rival so that it can no longer walk to feed.
Hippos use the same trails over and over to travel on their ranges. These trails can become five to six feet deep, literally turning into tunnels.
Since hippos are often born underwater, babies can swim the instant they're born.

CONSERVATION STATUS

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.

COMMON HIPPOPOTAMUS (Hippopotamus amphibius): SPECIES ACCOUNTS

Physical characteristics: The common hippo measures up to 106 inches (270 centimeters) in length and has a shoulder height of 54 to 60 inches (137 to 152 centimeters). It weighs up to 4,000 pounds (1,800 kilograms).

Geographic range: Although this hippo is found in thirty-five sub-Saharan countries, many of those populations are small, especially in West Africa. So, there aren't as many common hippos as it might seem there would be. Zambia, Tanzania, and the Democratic Republic of the Congo have larger populations of this species.

Habitat: The common hippo needs water deep enough to keep its body wet or the skin will crack from overheating. For the same reason, it enjoys wallowing in mud. Hippos leave the water at night to feed, sometimes traveling as far as 20 miles (32 kilometers) in one night.

Diet: The common hippo grazes on short grasses. The grasses become known as hippo lawns because they are nipped off so close to the ground. There has been one case of cannibalism (eating one's own species) documented.

Behavior and reproduction: The hippo is a difficult species to study because it is aggressive toward humans. The male common hippo is territorial in the water, where he defends mating rights with the female hippos in his range, but he is not territorial on land.

Hippos are known for their bellowing (shouting), but we don't know what role the bellowing plays in communicating between individuals. They also have at least three distinct calls underwater.

Common hippos mate and give birth in the water. Pregnancy lasts 240 days, at the end of which the female seeks solitude in the water. We do not know how long baby hippos nurse (drink mother's milk), but calves remain with their mothers until after the birth of the next calf. Common hippos are polygamous (puh-LIH-guh-mus; have more than one mate).

Common hippopotamuses and people: This species is highly dangerous to humans, particularly fishermen who invade their territories. It raids crops and is particularly fond of rice. Humans hunt the common hippo for its meat and ivory.

Conservation status: Though not listed by the IUCN, the total number of common hippos is low, especially in West Africa, where populations are as low as fifty. In order to rule out extinction, populations need to number at least five hundred in any given region or area. ∎

PYGMY HIPPOPOTAMUS (Hexaprotodon liberiensis): SPECIES ACCOUNTS

Physical characteristics: Measures 5 to 6 feet (1.5 to 1.8 meters) in length and weighs 350 to 600 pounds (159 to 272 kilograms). Though similar to the larger common hippo in body shape, the pygmy's head is proportionately smaller. Also, its eyes, ears, and nostrils do not sit as high on the head. Its legs and neck are longer, and the skin is closer to black than brown.

Geographic range: Found in Liberia, Guinea, Ivory Coast, and Sierra Leone.

Habitat: Pygmy hippos are forest animals that spend the day in or near water and roam the land at night to forage. They also live along swamp borders.

Diet: Feeds on a diet of fruits, ferns, and grasses.

Behavior and reproduction: These hippos are usually found in pairs, as they are not as social as common hippos. They also are not as aggressive.

Females give birth either on land or in water after a pregnancy lasting 190 to 210 days. Each delivery results in one calf that weighs an average of 12.6 pounds (5.7 kilograms). Unlike the common hippo calves, pygmy calves will not follow their mothers on food expeditions, but stay in hiding and wait to be nursed two or three times a day. By the age of five months, they weigh ten times more than they did at birth. These calves live with their mothers until the age of three years.

Pygmy hippopotamuses and people: Pygmy hippos are not a threat to humans but have been known to injure hunters and damage crops.

Conservation status: Listed as Vulnerable by the IUCN due to hunting and habitat loss from logging. Several national parks in the Ivory Coast and Guinea have been established to give protection to the pygmy hippo. ∎