There are two kinds of hippopotamus.
Hippos live on land and in the water.
They can stay under the water for a long time.
A baby hippo is a calf.
Hippos are fierce.
What is a hippopotamus?
The hippopotamus is a mammal.
It lives both in the water and on land, so it is amphibious or semi aquatic. The word 'hippopotamus' means 'river horse' because they walk or run along the bottom of the river, even though they are good swimmers. The name is usually shortened to ‘hippo’.
A common hippopotamus. ©Getty Images
There are two species, or kinds, of hippopotamus: the common or river hippopotamus and the pygmy hippopotamus. Both are herbivores.
A young hippopotamus is called a calf. Its father is a bull and its mother is a cow.
Common hippos live in groups, and a group is called a bloat of hippos.
Pygmy hippos are solitary, which means they live alone. Sometimes they are in pairs.
Habitat
The habitat of the common hippopotamus is grassland areas where there is permanent still water, not too deep and without many rocks at the bottom of the pool.
Pygmy hippo habitat is forest near swampy areas. ©Getty Images
The habitat of the pygmy hippopotamus is in forests in western Africa, near swampy areas.
Body
The pygmy hippopotamus is much smaller than the common hippo, standing at less than 1 metre high at the shoulder and weighing about 250kg. Its neck is longer, its head is rounder and narrower, and its eyes are not at the top of its head. They spend less time in the water than the common hippopotamus, but have the same adaptations to being in water.
A hippo walking on the river bed, with ears flattened and nostrils shut.A clear membrane closes over the like an eyelid so the animal can see underwater. ©Getty Images
The common hippopotamus weighs about 3 tonnes (male) and 1.5 tonnes (female). It is the third largest land animal (after the elephant, which is the largest, and the white rhinoceros). Its feet have four webbed toes. Hippos have very thick skin and almost no hair.
Hippos do not sweat, so they need water or mud in order to keep cool. When out of water for a while, its skin sometimes oozes a pinkish oily liquid. Some people think this is blood but it is not. This liquid prevents the skin from drying out and acts as a sunscreen. Under the skin a hippo has a thick layer of fat, which helps keep it warm in the water.
Hippos can stay almost completely submerged and still see, hear and smell what’s going on. ©Getty Images
Eyes, ears and nostrils are on the top part of the head so that when floating in the water they can see, hear and breathe easily.
They keep watch for crocodiles. A male hippo also keeps watch for other males who may want to take over his territory and females.
Hippos have short, flattened tails. The tail acts like a bat to spread the male's poo to mark its territory.
Underwater, hippos run or walk along the bottom, with their ears pressed down flat and their nostrils clamped shut by tiny muscles. They have what is often called a third eyelid, clear membrane that covers their eyes and work like goggles so they can see underwater. Their heart rate slows down so they can stay underwater longer. They generally come up for air every 6 or 7 minutes, but they can stay under for about 30 minutes.
Common hippo's habitat is river or pools in grasslands ©Getty Images
Behaviours
Hippopotamus live both on land and in the water, which means they are amphibious or semi aquatic. The common hippopotamus comes out of water at night to feed on grass, often walking up steep banks and always following the same paths. They generally return to the water at sunrise to spend the morning dozing. They may lie on the banks to sun bake if it is not too hot or windy. On land they can run at about 30 kilometres an hour if they have to, but only for a short distance.
A show of aggression as a male protects his females. © Getty Images
Common hippopotamus groups vary in size. In a large pool, a group could be as large as 60. Males are very territorial. Hippopotamus are very aggressive animals and easily enraged. In fact, they are probably the most dangerous animals in Africa. They 'yawn' more and more as they get angrier, showing their big teeth as part of their threat display.
A pygmy hippopotamus. ©Getty
Pygmy hippos live alone or in pairs. They also feed at night. They eat grass, leaves and fruit.
Not a great deal is known about these rare animals.
Life Cycle
A female common hippopotamus gives birth to a single calf, very rarely twins, about 8 months after mating with a male. Hippopotamus calves are small, about 25kg, born on land or in shallow water.
Common hippo and calf. The calf is climbing onto its mother’s back to rest. ©Getty Images
Hippos are mammals, so the young drink milk from their mother’s body. The calves generally suckle milk while underwater, closing their nostrils in order to do so without drowning. The calves of the herd play together. In the water, young ones are often seen resting their heads, or standing, on an adult's back, usually their mother's, because the effort to keep afloat tires them too much. Until a calf is strong enough to walk far, the mother leaves it with other females to babysit when she goes to feed.
Pygmy hippopotamus with calf. ©Getty
A pygmy hippopotamus female gives birth about 6 to 7 months after mating with a male. The calf is born at the water’s edge or in shallow water.
Being mammals, the calf of both species drinks mile from its mother before gradually learning to eat vegetation.
Two male hippos fighting. Hippos can inflict serious damage in a fight. Getty Images
Conservation and Threats
The common or river hippopotamus is classified as Vulnerable, meaning if the numbers continue to fall it may be listed as Endangered.
The pygmy hippopotamus is classified as Endangered.
Habitat loss is a major threat to both kinds of hippo.
It’s a good idea to get information from more than one source!
Read more about hippos
http://www.sciencekids.co.nz/sciencefacts/animals/hippopotamus.html
http://www.ducksters.com/animals/hippo.php
Read about pygmy hippos
https://animals.sandiegozoo.org/animals/pygmy-hippopotamus
