The name hippopotamus comes from some ancient Greek words. Hippo means horse and potamus means river. Therefore hippopotamus means river horse. They do spend most of their time in the river, but they are more like a pig than a horse.

Hippopotamus is the fifth largest living land mammal, after the three types of elephant and the white rhinoceros. They are the heaviest even-toed ungulates. Their hide alone can weigh half a ton. They weigh between 1.5 and 3 tonnes for a male hippo. The female hippo weighs about 1.5 tonnes. Older male hippos can get much larger, reaching at least 3.2 tonnes and sometimes they can even weigh 4.5 tonnes. Male hippos appear to continue growing throughout their lives. However,  female hippos will stop growing at around 25 years old. The white rhinoceros is about 1.5 to 3.5 tonnes and the three species of elephants are about 3 to 9 tonnes.  Therefore, the hippopotamus is one of the largest 4 legged mammals. Most hippos are weighed when they are killed. It is very hard to weigh them when they are alive because of their enormous size.

The Hippopotamus is one of the most dangerous animals in Africa!
The Hippopotamus is one of the most dangerous animals in Africa!

Although the hippopotamus is heavily built and has short legs, it can easily run faster than humans on land. It can run at 30km/h (18 miles per hour) over short distances. They are about 3.3 to 5.2 metres long (11 to 17 feet), including a tail about 56 centimetres (22 inches) long. They are semi-aquatic creatures. They live in rivers and lakes in central and southern Africa. Tanzania and Zambia have the largest populations of hippos. They are one of the most aggressive creatures in the world, especially when their young calves are with them. They are often regarded as one of the most dangerous animals in Africa. They are dangerous to go near because they do attack humans whether in boats or on land. Their population is dwindling due to illegal hunting for their meat and their ivory canine teeth, also because of habitat loss. Hippos can live up to 40 years in the wild and 50 years in captivity.

The hippos have a barrel-shaped torso, a huge mouth which can open 1.2 metres (4 feet) wide. They have teeth on the lower jaw. Its greyish body has a thick skin which is nearly hairless. Their lips are almost 70 centimetres long (27 inches). It is about 1.5 metre (5 feet) tall at the shoulder. It has a short tail and small eyes. Eyes, ears and nostrils are on the top part of the head so they actually stay in the water or mud and still see, hear and breathe easily, without being noticed by predators or getting sunburnt.

A male hippo is called a bull and a female hippo is called a cow and their baby is called a calf.  They are herbivore and prefer to eat short grasses of African plains. During the day they will remain cool by staying in water or mud. They stay underwater for up to 5 to 6 minutes but young hippos will stay underwater for only about half a minute. Mother hippos give birth in the water – so a baby hippo can actually swim the moment they are born! They are nursed underwater too. They will only nurse (drink milk) on the land if their mother decides to leave the water. They are about 25 – 45 kilograms (55-100 lb) at birth and have an average length of 125cm (50 inches). The mother hippo will help her calf to the surface to take their first breath and teach it to swim. The mother will also protect her calf from crocodiles, lions and also male hippos. Male hippos do not normally attack the calf on land but sometimes attack the calf in the water. A calf begins to eat grass when it’s 3 weeks old, but its mother will continue to give it milk for about a year. The calf is able to take a deep breath, close its nostrils and ears and dive underwater to get its mother’s milk. A mother will normally give birth to only one well-developed calf at a time, although sometimes she will have twins. The calf will often rest on its mother’s back when the water is too deep for it.

Hippos were once thought to be able to sweat blood. The truth is the hippos don’t actually sweat blood but they secrete a pinkish oily liquid which protects their skin against heat and sun – a natural sunscreen lotion to keep their skin moist in the hot African climate.

The Hippopotamus is the fifth largest land animal
The Hippopotamus is the fifth largest living land animal

Hippos have a three-chambered stomach and they do not chew their cud. They feed at night. They will leave and enter the water at the same spot and graze for 4 to 5 hours. They might walk up to 8km (5 miles) just to look for food. They eat about 70kg (150 lb) of food each night. They depend on tiny organisms in the stomach to digest the plants which they eat.

Hippos can sink down, then walk or run along the bottom of a river. The hippo’s feet are partially webbed  but in fact the hippo is not a good swimmer, and not able to float. The hippos which you see in the water are basically just standing in the shallows – or, more likely, lying down. If the river water is deep, hippo will usually propel themselves by leaps – pushing off from the bottom like an overweight ballet dancer. They move at speeds up to 8km/h (5 mph) in the water. But young hippos or calves are able to float and usually move by swimming, propelling themselves with kicks of their hind legs. Adult hippos usually come up for air every 3-5 minutes. The young hippos have to breathe every 2-3 minutes. Amazingly the process of resurfacing to breathe is automatic. The hippos even do it while sleeping! The adult hippos will close their nostrils and press their ears flat against the sides of their heads when they are in the water.

Hippos appear to communicate verbally through grunts and bellows. They have unique ability to hold their head partially above the water and send out a cry that travels through both water and air. Other hippos above and under the water will respond to that cry. They rarely kill each other, even in territorial fights. The bulls will fight with each other using their enormous canine teeth. When their habitat becomes crowded, the bulls will sometimes kill the calves, but this behaviour is uncommon. Sometimes there are hippos which kill and eat other hippos, it will happen only when that particular hippo is distressed or sick.