Hippopotamus

The hippopotamus (_Hippopotamus amphibius;) is a large semiaquatic mammal that lives in sub-Saharan Africa. It is often called a hippo for short. Hippos are one of the largest land animals, bigger than most other mammals except elephants and rhinoceroses. They have barrel-shaped bodies, wide mouths with large canine teeth, almost no hair, short legs, and are very heavy.

Hippos spend much of their time in rivers, lakes, and mangrove swamps. Male hippos, called bulls, guard a special area of water where they live with a group of females, called cows, and their babies. Hippos give birth and mate in the water, and they stay in water or mud during the day to stay cool. At night, they come out to eat grass by themselves.

Even though hippos look slow and heavy, they can be dangerous because they act in unpredictable ways. Hippos face threats from losing their homes and from people who take their meat and ivory (their large teeth).

Etymology

The word "hippopotamus" comes from Ancient Greek. It is made from two words: one meaning "horse" and the other meaning "river". So, it literally means "horse of the river". In English, we usually say "hippopotamuses" when talking about more than one hippopotamus.

Taxonomy and origins

The common hippopotamus and the pygmy hippopotamus are the only living members of the family Hippopotamidae. They are classified with other even-toed ungulates in the order Artiodactyla.

Hippos and whales share an ancestor that lived long ago. One group became whales, while the other became hippos and their relatives, the anthracotheres. Over many years, hippo ancestors moved across Africa and Eurasia, leading to the hippopotamus we know today.

Characteristics

The hippopotamus is a very large land animal, only smaller than elephants and some rhinoceroses. Adult males weigh about 1.48 tons, while females are a bit lighter. They can grow up to about 5 meters long, with males being taller than females.

Hippos have strong bodies built for life in water. Their heavy bones help them stay submerged, and their webbed toes make swimming easier. Even though they look chubby, they don’t have much fat. Their eyes, ears, and nostrils sit high on their heads so they can stay above water while mostly submerged. When underwater, they can close their nostrils and ears, and special membranes cover their eyes.

Hippos have very strong jaws with big muscles, allowing them to open their mouths wide. Their teeth, including long canines, are mainly used for fighting, not eating. They use their lips to grab grass, which they then pass to their molars to chew. Their skin is thick and mostly hairless, and it secretes a natural red substance that acts like sunscreen, protecting them from the sun’s harmful rays.

Distribution and status

The hippopotamus, known as Hippopotamus amphibius, once lived in Europe between 560,000 and 30,000 years ago, mainly in Southern Europe like the Iberian Peninsula, Italy, and Greece. During warm periods, they lived as far north as Great Britain and western Germany. These ancient hippos were closely related to the ones living in Africa today.

Today, hippos are mainly found in rivers and lakes across Africa, from the Democratic Republic of the Congo and Uganda to Kenya, Ethiopia, and South Africa. Their numbers have dropped due to losing access to water and being hunted. The International Union for Conservation of Nature lists them as vulnerable. In some places, like Virunga National Park, their numbers fell during wars but are now recovering with better protection. There is also a small group of hippos in Colombia, descended from escaped captives, which is being managed by experts.

Behaviour and ecology

Hippos spend most of their time in water and need to stay close to grass. They usually live in freshwater places but can also be near where rivers meet the sea. They like calm waters with gentle shores, though male hippos sometimes go into faster, rockier waters.

Hippos mainly eat grass, and sometimes other plants. They stay in water during the day to stay cool and come out at night to eat. Each night, a hippo can walk several kilometres and eat around 40 kilograms of grass before returning to the water by dawn.

Hippos move in water by walking or pushing off the bottom and need to breathe every few minutes. On land, they trot and can reach high speeds, though they cannot jump. They sleep both on land and in water, sometimes even while mostly underwater.

Hippos can change the land around them by walking the same paths often, which clears vegetation and can change the direction of small rivers or swamps. Their waste in the water also affects the environment.

Social life

Hippo groups, called pods, can include over 100 hippos. Adult hippos do not form close bonds with each other. Male hippos claim areas of water as their own, where they have access to any females there. Younger males stay nearby but must show respect to the older male. If a younger male challenges the older one, a fight may occur.

When hippos come out of the water to eat, they usually go alone. They sometimes spread their waste while moving their tails, which may help mark paths to their feeding areas.

Reproduction

Female hippos are ready to have babies at around five to six years old, and males at about seven and a half years. Most births happen during the wet season. After a female becomes pregnant, she will not get pregnant again for about 17 months.

Hippo mothers give birth to one calf at a time, usually in water or on land. The mother protects her calf closely, and young hippos stay by their mother’s side for about a year.

Interspecies interactions

Hippos share their homes with animals like crocodiles, lions, and hyenas, which sometimes prey on young hippos. Adult hippos are usually safe from these predators because of their size, though very large groups of lions can sometimes attack them. Hippos often chase away crocodiles from their areas.

Hippos sometimes visit special spots where small fish clean parasites off their bodies. This helps both the hippo, which stays cleaner, and the fish, which get food.

Relationship with humans

People have known about hippos for a very long time. Early humans and even Neanderthals hunted hippos. Ancient Egyptians thought hippos were very fierce and showed them in paintings and stories.

Hippos have also been written about by famous people from Greece and Rome. Some hippos have even become famous, like Huberta, who traveled a long way during a difficult time in South Africa.

Hippos have been popular in zoos for thousands of years. The first hippo in a modern zoo was Obaysch, who came to the London Zoo in 1850 and became a big attraction. Today, zoos have special places for hippos with big tanks and viewing areas for visitors.

Hippos have special meanings in many cultures. In Egyptian stories, a goddess with a hippo head shows strong love for her children. Some African groups use hippo masks in their traditions. Hippos have also appeared in many stories, songs, and movies, like in the Disney film Fantasia and the game Hungry Hungry Hippos.