Hippopotamus (Hippopotamus Amphibius
aka Common Hippopotamus, East African Hippopotamus or Hippo Appearance
Hippopotamus are unmistakable, but there are some interesting facts that many are unaware of. These are huge mammals, the third largest, after Elephants and Rhino, with big heads, broad muzzles and short legs that have just 4 toes. They have a large pair each of incisors and canines in their bottom jaw, that grow continuously and are used in fighting and predator-protection. The Hippopotamus' canine teeth grow up to 1' 6" (50cm) long and act like tusks, when fighting. With jaws wide open, a Hippo's mouth can span 4' (1.2 metres) and open as wide as 150 degrees. In addition, they have 42 teeth toward the back of their mouth, for chewing their food.
Mostly brown in colour, they have pink around their eyes, ears, mouth, under-necks and bellies. They are hairless, except for on their ears and bristles on their chins and tails. Their skin is often covered in wounds and scratches, from fighting.
Hippopotamus skin is approximately 2" (5cm) thick and covered in pores that excrete "blood sweat". Actually, it is neither blood or sweat, it is a clear substance that after appearing on the surface, quickly turns red, giving the appearance of "blood sweat". After a period of time it turns brown. Experts believe that this secretion is a form of both sunscreen and bacteria inhibitor. However, this animal's skin is extremely sensitive to sunlight and only comparatively short periods of time are spent out of the water 'sun-bathing'.
Hippopotamus males grow to be 5' (1.5 metres) at the shoulder, 14' (4.25 metres) long and weigh up to 2 ton (2,000 kg). Females grow to be 5' (1.5 metre) at the shoulder, 11' (3.4 metres) long and weigh up to 1 ton (1,000 kg). Resident
Hippopotamus are seen in many of Kenya's parks with suitable habitat, notably Lake Turkana, Meru NP, Masai Mara GR, and Tsavo National Park. They are seen where there is both permanent water (rivers, lakes, marshes or dams with soft bottoms) and nearby grasslands. Not normally seen above 2,500 metres. Longevity
Hippopotamus always mate in water. After a gestation period of around 235 days, a single calf weighing approximately 100lbs (45kg) is born in water, or on land, under dense cover. The calf is suckled first on land, then in the water It begins to graze at age 4 - 6 months, after first taking small amounts of its mother's dung. Like Elephants
, it is born with sterile intestines and requires bacteria from its mother's dung to 'kick-start' its digestive system. Females reach sexual maturity at 4 years old, males at 7 years and Hippopotamus live until approximately age 35.
It is believed that Hippopotamus give birth to coincide with the rainy season. After giving birth, a female will not normally ovulate again for 9 months. Predators
Hippopotamus calves are predated by Nile Crocodile
, Spotted Hyena
and man, for their ivory canines and incisors. Fully grown Hippopotamus are rarely predated. Behaviour
Extremely territorial, a single male Hippopotamus will usually control up to 10 - 15 females, fighting off other males, leading to terrible injuries from one of the largest animals on the planet. Larger schools and single, or small groups of males are not uncommon.
Males threaten each other by displaying their wide-open jaws, showing the interior of their mouths and teeth. They frequently fight and more fiercely so than most other animals. They are also dangerous to man, overturning canoes and small boats that come within their territory. Despite its fat shape and short column-shaped legs, it is capable of running 30 km/h (19 mph) and therefore faster than man. Hippopotamus are one of Kenya's most dangerous animals, so it's surprising they are not one of The Big Five.
Hippopotamus spend all daylight hours in or around water, otherwise their hides can become badly sun burned. Despite being water-based, they do not have webbed feet and do not swim well, but can spend up to 6 minutes submerged and having a specific gravity higher than water, can walk along the bottom. On rising to the surface, they expel the water from their sealed nostrils. Eyes, ears and nostrils are all positioned high-up on the head, keeping them out of water while the body is submerged.
At dusk, they move to their pear-shaped grazing grounds, spanning out for as much as several kilometres from water. The adult males are always the last to leave the water and all follow well-defined paths, starting with deep grooves in the banks of the waterway.
Hippopotamus are often seen with birds on their backs; Cattle Egret
or Oxpeckers. The latter clean wounds and keep them free of ticks, although you can read more about those species on the relevant gallery.
Head bulls mark their territory by scattering dung with their tails, both in their watery home and on their resident pastures, although it is not felt that pastures are as territorially defended as the water. Diet
Hippopotamus are herbivorous, mostly grazing on short grass, pulling the grass away from the roots with strong lips. They very occasionally eat plant leaves near the ground. They eat approximately 130 lbs (60kg) per night. Despite only eating vegetation, the Hippo's bite has tremendous force of some 1,820 pounds per square inch. Although they have three stomachs, they do not ruminate (chew the cud), instead, the separate chambers ferment the food, breaking it down.
Hippopotamus sometimes destroy fishermen's nets but are of benefit to fishing because of the dung they excrete. It contains a valuable fertiliser, which, together with their moving the muddy bottom, liberating nutrients into the water, creating an ideal environment for fish. Also, Hippopotamus are often surrounded by a particular fish belonging to the genus Labeo
, which feed on vegetable matter and excreta. The Hippopotamuses open their mouths wide, signalling their readiness for being cleaned of parasites by these fish and a form of mutualism happens, where the animal benefits from the cleaning, while the fish gains food. Other Hippopotamus Facts
Once classified with Pigs, DNA now reveals the closest relative to Hippopotamus are Wales & Porpoise.
During the Ice Age, (1.8 million to 13,000 years ago) Hippopotamuses inhabited England, Europe and Asia, as well as Africa. The earliest known Hippopotamus fossils, found in Africa, date to around 16 million years ago.
The name Hippopotamus (Hippopotamus Amphibius) is derived from the Greek "River Horse".
Hippopotamus make a variety of calls, from winnying, roaring grunts and snorts, to tusk gnashing.
The collective noun for Hippopotamuses is a herd, bloat, dale, or pod.
Images taken in Kenya's Masai Mara and Olare Orok Conservancy.