Despite its resemblance to pigs and other hoofed animals, the hippopotamus – among the largest of all the modern land mammals – bears a closer taxonomic relationship to whales, dolphins and porpoises. Its name means “River Horse” in ancient Greek. Semi-aquatic, it lives in freshwater rivers, lakes and wetlands by day and grazes in adjacent grasslands by night. With a body density that limits its buoyancy, the adult hippo propels itself through the water by leaping or simply walking, with surprising grace, along the bottom, surfacing to breathe about every five minutes. It even sleeps, perfectly comfortably, while completely submerged, rising to the surface to breathe without ever awakening.
According to WhoZoo, “The hippopotamus is an extremely fat animal, with a round body, short, stocky legs, and a large head.” According to the African Wildlife Foundation, “It was considered a female deity of pregnancy in ancient Egypt.”
- Size and Weight: The adult male – which appears to grow throughout its life – reaches lengths of up to 15 feet from the tip of its nose to the base of its thick, two-foot-long tail; stands about five feet high at the shoulder; and weighs, typically, between three and one half to four tons. The female – which reaches maximum size at some 25 years of age – is significantly smaller, weighing about one and a half to two tons.
- Body: Barrel-shaped and nearly hairless.
- Eyes, Ears and Nostrils: Located on top of skull, allowing the animal to see, hear, breathe and smell while remaining virtually submerged in water. The eyes have clear membranes that, like goggles, provide protection and underwater vision. The ears and nostrils function like valves, closing out water when the animal is fully submerged.
- Mouth: Large and wide opening (up to four feet), with wide snout and thick raspy lips used for foraging, and with continuously growing canines and incisors used for grazing—and for battling rivals. (The lower canines may grow up to 12 inches above the gum line.)
- Legs and Feet: Short thick legs with web-toed feet that spread to distribute the animal’s weight evenly so that it can be adequately supported on land.
- Hide: Nearly two inches thick, weighing as much as half a ton. Excretes a reddish oily substance (sometimes called, erroneously, “blood sweat”) that acts as a sunscreen and, apparently, as a disinfectant. The “hide is so thick and tough that when dried it can be made into spear-shafts,” said the ancient Greek historian, Herodotus.
- Color: “…brown to grayish purple, with pink underparts and skin creases,” according to the Smithsonian National Zoological Park.
- Senses: Hearing, smell and sight excellent, say most accounts.
The hippo may be the only land mammal that can hear “in stereo—one channel in
air and a second underwater,” according to Stephen Hart, The Language of
Distribution, Habitat and Diet
According to the International Union for the Conservation of Nature and Natural Resources (IUCN) – the world’s leading authority on the conservation of species – the Hippo ranges across most of the African countries south of the Sahara Desert, although it has been extirpated from much of its original range. Historically, a large population lived in the Nile River of eastern Africa, but it has now been totally exterminated. At present, says the IUCN, the largest populations occur in southeastern Africa, in the countries of Mozambique, Zambia, Tanzania and Malawi.
The hippo spends the daylight hours wallowing and sleeping in the coolness of shallow waters and mud. It spends the night foraging in nearby ranges of grasslands. It may cover several miles in an evening, feeding primarily on short soft grasses but also on fallen fruits and leaves. Compared with other large mammals, the hippo eats relatively modestly, perhaps 80 or 90 pounds of grass in a day, but its diet is nevertheless sufficient given its indolent, low-energy daytime lifestyle.
Behavior and Life Cycle
A mature bull hippo may lay claim to a comparatively small realm of water,
for instance, a few hundred yards of a river. He presides over a Hippo “pod”
that may include a dozen to several dozen cows, calves and submissive bachelor
bulls. The population numbers and mix may vary, depending on the availability
of food and water. During the day, the cows, with their calves, and the bachelors
tend to segregate by gender within the pod, wallowing and sleeping in separate
groups. They do not appear to form strong social bonds. The mature bull keeps
largely to himself. At night, except for mothers, which keep their young nearby,
the animals of the pod strike out on their own to feed individually for several
Not a dainty animal, the hippo defecates and urinates in the very water it calls home, sometimes creating fetid shorelines that test – especially if the animal has open wounds – the effectiveness of the disinfecting “blood sweat.” According to the Smithsonian National Zoological Park, male Hippos meet, backside to backside, at the boundaries of territories and use their thick tails to fling feces and urine at each other. They then usually just simply walk away from each other.
Evil tempered and aggressive, the hippo ranks high on the list of the most dangerous large mammals in Africa. Hippos may fight among themselves, using canines and incisors as sometimes deadly weapons, especially during instances of competition for limited resources. A female hippo may attack a bull hippo if she thinks it might threaten her young. The hippo attacks any predators, for example, crocodiles, that could threaten the young. It may even attack humans in boats or on land (where it can outrun even a world-class sprinter for short distances).
The male hippo reaches sexual maturity at about seven or eight years of age, and the female, at about five or six years of age. In southeastern Africa hippos usually mate in the water, near the end of the wet season in the summer. About eight months later, the female gives birth, often in the water apart from the pod, near the beginning of the wet season in late winter.
According to S. K. Eltringham, The Hippos, a newborn hippo, weighing about 60 to 110 pounds, swims or is boosted by its mother to the surface to draw its first breath. Later, it rides on its mother’s back, as if she were a raft, in deep water. It nurses either underwater or on dry land. It begins grazing within a few weeks. It becomes fully weaned after about a year. Hippos may live for up to 40 to 50 years.
Across much of Africa, with its growing and expanding human population, the hippo’s numbers have slipped because it has lost access to suitable habitat in many areas. Additionally, it has fallen to poachers, who kill the animal for its meat and its superior ivory. The hippo’s total number has fallen by 7 to 20 percent, to about 125,000 to 150,000 since 1996, according to the IUCN. An adult hippo has essentially no predators (other than man), but a young hippo may fall prey to a Nile crocodile, a lion or a spotted hyena. The hippo species is listed as “vulnerable” by the IUCN.
- Hippos have been divided into five subspecies by some field biologists, but the list has never gained universal acceptance.
- The hippo has a relative – the pygmy hippopotamus – which weighs only a few
hundred pounds. It has become virtually extinct in the wild, with only a few
remaining animals in western Africa.
- The hippo is extremely vocal, producing hundreds of different calls, some
as loud as 115 decibels—a sound level comparable to a nearby clap of thunder.
- The hippo allows the red-billed oxpecker, a relative of the starling, to
alight on its back to search for ticks and other parasites.
- The hippo had medicinal uses, according to Pliny the Elder, the first century Roman who wrote the famed encyclopedia Natural History. The hippo’s hide, he said, “reduced to ash and applied with water, cures superficial abscesses... The hide from the left side of his forehead…restores hair lost through mange.”
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