Hippo Facts

Tadashi

Tadashi

Published: 25 Nov 2021

Hippo Facts, Sleepy Hippos

Only a few other animals enjoy as much popularity as the hippopotamus. In fact, when people start thinking about zoos or wild animals, hippos come to mind as quickly as lions, zebras, and giraffes, among others. That said, there’s a lot about hippopotamuses that don’t count as common knowledge. Learn all about them with these 50 Hippo facts!

  1. Male hippos typically have an average weight of around 1500 kg.
  2. In contrast, female hippos weigh less, typically around 1300 kg.
  3. Their bodies can also grow over 5 meters long, including the tail for up to 56 cm long.
  4. Hippos typically stand between 1.3 and 1.6 meters tall.
  5. Despite their size and weight, hippos can move surprisingly fast, with a top speed of around 30 kph.
  1. Hippos share a common ancestor with whales from around 60 million years ago.
  2. The hippos’ ancestral group, the anthracotheres, first evolved during the Eocene Epoch, between 56 to 34 million years ago.
  3. The anthracotheres split with the ancestral whales around 54 million years ago.
  4. They later migrated across Africa and Eurasia starting around 16 million years ago.
  5. The first recognizable hippos evolved around 8 million years ago.
  6. The other anthracotheres went extinct by the Pliocene Epoch, between 5 to 3 million years ago.
  7. Hippos in Eurasia went extinct between 50,000 to 16,000 years ago.
  8. The Greek historian Herodotus described hippos in his work The Histories in 440 BC.
  9. Roman naturalist, Pliny the Elder, did similarly in his work, Naturalis Historia, in 77 AD.
  10. Humans in Madagascar wiped out the hippos there within the last 1000 years.
  1. Hippos count as the world’s 3rd largest mammals, coming after elephants and rhinos.
  2. Hippos have closer relations to whales than to pigs and other similar mammals.
  3. Other close relatives of theirs include the American bison, dromedaries, and the giraffe.
  4. Not counting whales, hippos have the heaviest weight among their relatives.
  5. They currently have the “vulnerable” designation for conservation purposes.
Table of Contents

The hippo’s name has a story of its own.

Hippo itself comes as a shortened form of hippopotamus, which comes from the Ancient Greek hippopotamos. That word, in turn, comes from two other words, hippo, Ancient Greek for a horse, and potamos, or river. Together, they give the hippo’s Ancient Greek name the meaning of horse of the river.

In Modern English, hippo has several other forms, such as the common hippopotamus, and the river hippopotamus. In its full form, the hippopotamus has two plural versions, the more common hippopotamuses, or the rarely-used hippopotami. The name also has a scientific version, given by Carl Linnaeus in 1758, Hippopotamus amphibius.

Hippo Facts, Hippo Walking
Image from Pixabay

Scientists recognize 5 different subspecies of hippo.

First, we have the Nile hippo, or the great northern hippo, which most people imagine when they hear the word hippo. As its name indicates, it originally lived in Egypt, but in a sad irony, the animal has since become extinct there. Today, it lives in Tanzania and Mozambique.

Then we have the East African hippo, which lives in the Great Lakes of Kenya, and in Somalia’s Horn of Africa. Next, we have the South African hippo, or the Cape hippo, which ranges from South Africa to Zambia further north. Then we have the West African hippo, also known as the Tchad hippo. As its name indicates, it lives in West Africa, ranging inland as far as Chad. And finally, we have the Angola hippo, which lives in the country of the same name, while ranging south to Namibia.

Hippos have several ancestral species.

These include Anthracotherium and Elomeryx, both of which lived during the Eocene Epoch. Elomeryx, in particular, had a very horse-like head, and together with Anthracotherium, lived not just in Africa and Eurasia, but even migrated to North America. Both species had gone extinct by the Miocene Epoch, between 23 to 5 million years ago. By then, new species had evolved to continue the leadup to the modern hippos, such as Merycopotamus and Libycosaurus.

The entire hippo subspecies once lived in Europe.

The European hippo, in particular, first evolved around 1 million years ago and went extinct just before the last Ice Age. Studies of its fossil discovered that the animal grew much larger than the hippos of today, weighing up to 3500 kg.

Then we have the giant European hippo, which grew even bigger, weighing up to 4000 kg. It also ranged the furthest north out of all hippo species, even living on the British Isles before going extinct.

And finally, we have Hippopotamus gorgops, the largest of all hippo species, able to reach a weight of up 4500 kg. It, too, has gone extinct just before the last Ice Age, and the causes still remain a mystery to modern science.

Various dwarf hippos evolved across the Mediterranean Sea during the last Ice Age.

Scientists still aren’t sure of how they reached the various islands of the Mediterranean Sea. Theories include they migrated across land bridges exposed by the lower sea levels, or even floated their way to the islands on ice. There, the limited resources of their new island homes caused them to develop insular dwarfism. Specifically, a form of evolutionary adaptation which reduces their size to adapt to said limited resources.

These dwarf hippos include the Cretan dwarf hippo, the Cypriot dwarf hippo, Hippopotamus melitensis from Malta, and Hippopotamus pentlandi from Sicily. Of these, only the Cypriot dwarf hippo survived past the last Ice Age, and only for a short time. Circumstantial evidence exists that humans may have hunted the Cypriot dwarf hippo, and could have contributed to its final extinction. However, scientists still consider the theory as controversial and need more study and evidence.

dwarf hippo
Image from Adobe Stock

Hippos have a distinct appearance.

Generally speaking, hippos have barrel-shaped bodies standing on four short legs, while their heads have long muzzles. Their legs, while short, also grow very thick, while their skeletons have what scientists call graviportal structures. Both developed as the animal evolved to support the massive weight of its body. In particular, their bodies have a design that lets them sink to and move along a river bottom. This also means hippos can neither swim nor float, which also reflects in their appearance.

Specifically, the position of the hippo’s eyes, ears, and nostrils are on top of its head. This allows the hippo to keep themselves out of the water while walking or even sleeping in water. This also means hippos avoid deep water, as they couldn’t keep their heads above it. That said, hippos are able to hold their breaths if they have to, even by up to 5 minutes long.

They also have distinct habitat requirements.

Scientists consider them semiaquatic animals, as they spend more time in the water than they do on land. That they have webbed feet like amphibians, reptiles, and some birds, further reinforces this. In fact, hippos will usually only leave the water to eat. This means hippos tend to live near large bodies of water, such as rivers and lakes.

As hippos typically avoid deep water, they stay close to the shore. And when they do leave the water, they can actually go far inland to look for food, as far as 15 km. They usually leave around dusk and spend up to 5 hours every night grazing before finally returning to the water. This means in addition to plentiful water, hippo habitats also need plenty of plant life nearby for them to feed on.

They also use various sounds to communicate with each other.

Scientists have recorded these sounds, and described them as growling, honking, squeaking, and whining. They’ve also recorded laughter, which may sound eerily similar to human laughter. Hippos can get so loud, they can be heard almost 2 km away, and even further away when they vocalize underwater.

Scientists still aren’t sure what the sounds actually mean, but they can deduce the generalities. These include warnings of danger, a signal to stop moving or to keep going, or even simply addressing each other.

Hippos can also suffer from sunburn.

It results from their semiaquatic nature, which leaves their skins very sensitive to solar radiation. The fact that hippos have no hair makes it worse, as it leaves their skins even more exposed to the Sun.

That said, hippos have evolved a way to get around this. Specifically, hippos naturally produce a kind of sunblock, which some scientists call blood sweat. It’s not actually blood, with the name coming from the red color of the substance. In fact, it first gets produced as a colorless liquid but quickly turns red after getting exposed to air and the sun. Coating their skin, it absorbs solar radiation, with scientists noting it works especially well against ultraviolet radiation. This keeps the hippo from getting sunburn.

Blood sweat also has a natural antibiotic effect, which also helps keep hippos from developing skin infections.

Hippos usually have a simple diet.

They mostly eat grass and only rarely eat other plants, like tree leaves or various aquatic plants. Calves, in particular, eat their mother’s shit shortly after getting born, as hippos are born with sterile intestines. Eating shit introduces the necessary intestinal bacteria to their systems for them to properly digest their food in the future.

Scientists have also recorded hippos rarely scavenging dead bodies left behind by predators. They’ve also recorded them cannibalizing the dead bodies of their own kind. However, hippos can’t properly digest meat, as they aren’t actually omnivores.

Further studies of such abnormal behavior have led scientists to conclude that hippos acting as such do so out of psychological disorders. That, or starved for food, they go looking for anything they can fill their stomachs with.

They have an important role in their habitats’ ecosystems.

Hippos actually shit in the water they live in, with the shit building up on the river bed below. In average amounts, this actually helps keep the ecosystem stable, as the shit provides nutrients for fish and underwater vertebrates. However, if too much shit builds up, it has a negative effect on the ecosystem instead. Bacterial life in the shit consumes the oxygen in the water and suffocates other aquatic life.

The regular grazing of hippos also has a positive effect on the surrounding landscape. In particular, they keep surface-level plant life from growing too much and choking the ground. Their regular movements also help keep the ground level by compacting it with their footsteps. In the long-term, though, scientists think hippos might actually cause minor changes to water channels by compacting the earth.

Hippos have a curious relationship with their predators.

On one hand, predators like crocodiles, lions, and even hyenas prey on hippo calves and juveniles. But on the other hand, hippos in large numbers can actually outright drive crocodiles or even lions out of a certain area. Between their size, weight, and surprising aggressiveness, most predators would actually run rather than try and fight adult hippos.

In fact, lions only ever attack adult hippos when they’re with the rest of their pride, and they first make sure the rest of the herd isn’t nearby. And even then, they usually only attack when the lone adult hippo already suffers from an injury or some other weakness first.

A male lion with a hippo kill
Image from Adobe Stock

They also have a symbiotic relationship with certain fishes.

Hippos regularly visit what scientists call cleaning stations, places where certain fish species like the goby live. There, the hippos open their mouths in the water, and keeping them open, let the fish in. The fish then pick at the hippos’ teeth, gums, and tongue, eating leftover food and even parasites.

The hippos will keep their mouths open until the fish leave, which only happens once they can’t find anything more to pick at. Only then will the hippos leave, their visit at the cleaning station done. In this way, everyone at the cleaning station benefits. The hippos get their mouths cleaned, and even avoid catching parasitic infections. At the same time, the fishes get plenty of food.

Hippos have a complicated society.

Well, for starters, hippos aren’t actually social animals at all, so it’s already a surprise that they even have societies at all. That said, they do seem to appreciate the concept of strength in numbers, even if they don’t really form social bonds. The closest they seem to develop usually involves a mother hippo and any daughters she might have.

Male hippos establish territories of their own in water, usually measuring around 250 meters on all sides. They then share this space with, on average, around 10 females, though, herds of up to 100 hippos have existed. Unmated males cluster together, but it isn’t unknown for mated males to tolerate male juveniles in their space. Hippos also always graze on their own, and never in groups.

Hippos don’t mate every year.

This comes from the fact that females don’t ovulate for at least 17 months after getting pregnant. Hippos typically reach sexual maturity between 7 and 8 years, with the mating season usually happening towards the end of the monsoon. This takes advantage of a hippo’s long pregnancy, around 8 months, ensuring calves get born at the start of the next monsoon.

Hippos usually birth only one calf at a time, with twins only rarely getting born. Both mating and birthing take place underwater, with calves similarly suckling underwater. Calves also tend to ride their mother’s backs when they travel through water.

Hippos also have a sister species, the pygmy hippo.

They live in West Africa, mostly in Liberia, with small populations in neighboring countries like Guinea, the Ivory Coast, and Sierra Leone. Pygmy hippos have a similar appearance to hippos, but grow much smaller. They usually grow up to only 100 cm tall, 175 cm long, and weigh up to 275 kg.

Hippo Facts, Pygmy Hippo
Image from Wikipedia

Pygmy hippos behave differently compared to hippos.

For one thing, pygmy hippos mate for life, unlike hippos which typically mate with multiple partners. Also pygmy hippos don’t live together, with each mated pair living on their own and accompanied only by any calves they might have. Pygmy hippos also tend to avoid confrontations, unlike the more aggressive hippos. Scientists have also seen them living in lairs dug into riverbanks, again, unlike hippos. It still remains unclear if they actually dig out those lairs, or if they take over other animals’ abandoned lairs.

They also have a more uncertain future compared to hippos.

Unlike the merely vulnerable hippos, pygmy hippos have a fully endangered conservation status. In particular, human development of their habitats makes up the biggest threat to the pygmy hippo’s survival. This usually involves forests getting chopped down for lumber, or to free up space for agriculture.

While pygmy hippos don’t get hunted for the ivory trade, they do get hunted for their meat. Even though Liberia has since banned this practice, it still widely goes on illegally, especially in the countryside. Aside from humans, other predators also prey on pygmy hippos, like crocodiles, leopards, and pythons.

Wild hippos pose a threat to nearby humans.

People traveling on boats near hippos can find themselves getting attacked by the animals if the boats get too close. While bigger boats can handle hippo attacks, or even scare them off, smaller boats can get damaged or even outright sunk. Once in the water, humans generally don’t stand a chance against angry hippos. Humans can get seriously injured, or even outright killed, whether by drowning or getting crushed by a hippo.

Hippos also sometimes break into farms and other property, causing even more confrontations with humans. On land, though, hippos suffer from a disadvantage against humans, especially those armed with modern weapons. After all, a hippo’s large size won’t protect it from a bullet to the head.

Hippos almost became an invasive species in the US.

This took place in 1910 when Louisiana Congressman, Robert Broussard, proposed introducing hippos to his state. He argued the hippos would help control invasive plant species, while also introducing new meat to American cuisine. His proposal received support from former US President, Teddy Roosevelt. The media also pushed for the proposal and even described hippo meat as lake cow bacon. In the end, however, the US Congress decided against allowing hippos to get introduced to Louisiana.

Hippos have already become an invasive species in Colombia.

This happened thanks to the infamous drug lord, Pablo Escobar, who kept pet hippos on his property in Colombia during the 1970s. After Escobar’s death, the authorities left the animals on the property, from which they eventually escaped. Once in the wild, they slowly but steadily multiplied, from only four animals in 1980, to at least 120 in 2018. Scientists predict that number could grow to at least 200 in the next 10 years, with unpredictable effects on the local environment.

The Colombian government had actually attempted to cull them as far back as 2009, only to stop after a public outcry. Later on, they caught and sterilized a male, but found it too expensive a solution, at $50,000 per animal. As of the present day, no concrete solution for the problem exists.

Hippos have long had a place in African culture.

The Ancient Egyptians associated hippos with Seth, the god of the desert, and Egypt’s protector against foreign enemies. They also associated hippos with Seth’s wife Tawaret, who protected women during pregnancy and childbirth. The Ijaw people of Nigeria wear hippo-themed masks when venerating water spirits. Nigeria’s Yoruba people also use hippo bones to predict the future. The San peoples of Southern Africa also feature hippos in their creation myth, while the Zulus associate hippos with courage. They saw how even lions avoided hippos, so they encouraged their warriors to do likewise. Specifically, become like hippos, that even lions would fear to come near them.

Hippo Facts, Ijaw Hippo Masks
Image from Wikipedia

They also enjoy widespread popularity as zoo animals.

Ancient Egyptian records testify to the presence of hippos in the private collections of the rich and powerful. Modern zoos, though, first began keeping hippos in 1850, when the London Zoo took in a hippo named Obaysch. Obaysch quickly became a celebrity, attracting up to 10,000 visitors per day, and even inspiring a song, Hippopotamus Polka.

This led to other zoos following the London Zoo’s example and including hippo exhibits of their own. Originally, zoo hippos had concrete enclosures with water pools, but starting in the 1980s, zoos modified or built new enclosures similar to natural habitats. The Toledo Zoo, in Ohio, USA, became especially famous for its hippos in 1987, when one of their hippos had a natural, underwater birth, instead of being taken to a veterinary clinic.

Pygmy hippos have also appeared in zoos.

In fact, scientists suspect that zoos may represent the only way for the animal to survive in the future. It helps that zoos actually have more investment in the pygmy hippo’s survival, as almost all research on the animal happens with them. This results from the pygmy hippo’s difficulty to be seen in the wild. So much so, in fact, that captive breeding of pygmy hippos have doubled between 1970 and 1991 alone.

Hippo Facts, Captive Pygmy Hippos
Image from Wikipedia

Hippos are also featured widely in western culture.

Child star Gayla Peevey made her debut in 1953 with the song I want a hippopotamus for Christmas. Flanders and Swann wrote two songs based on the hippo, The Hippopotamus, and Hippo Encore. Disney’s Fantasia featured a hippo as far back as 1940, while Hanna Berbera had a hippo character named Peter Potamus. More recently, the Madagascar film franchise features a hippo named Gloria. Hippo-themed merchandise such as toys, children’s books, and the like, also enjoy popularity among children in general.

A famous South African hippo once went by the name of Huberta.

In 1928, she left a waterhole in Zululand to travel 1600 km over the next three years to the Eastern Cape. In that time, she became a celebrity in South Africa, with crowds gathering whenever she passed by major settlements. Both the Zulu and Xhosa peoples also treated her with veneration when she passed through their lands.

Ironically, people originally thought her a male and named her Hubert. Eventually, however, despite receiving royal protection, a farmer shot and killed her in 1931. This caused a public outcry, and the farmer’s arrest and fine.

Huberta’s true gender became discovered when they recovered her body and had it preserved in London. On her return home, a crowd of at least 20,000 people welcomed her, before placing her body on exhibit in Amathole Museum in King William’s Town.

A hippo once became famous for his friendship with a tortoise.

This took place in Kenya, during the aftermath of the 2004 Indian Ocean Tsunami. A juvenile hippo was separated from its herd and ended up rescued by humans. Named Owen, they placed him in the Haller Park Rescue Center, where he lived as the sole hippo. There, Owen met Mzee, a tortoise that Owen may have mistaken for an adult hippo thanks to his large shell and brown color. Mzee originally hid from Owen in his shell, but the animals eventually bonded and became friends. Sadly, Owen grew too big to stay around Mzee, and the animals were eventually separated for their own safety.

They may also have appeared in the Bible.

Scholars think that hippos inspired the Behemoth, a giant monster mentioned in the Book of Job. This comes from the animal’s large size, as well as how humans can eat hippo meat. This, in turn, plays into the Bible’s prophecy of how at the end of the world, the righteous would eat Behemoth for food. Similarly, other scholars point out how Behemoth’s original Hebrew form, behemah, may have come from the Ancient Egyptians. However, most scholars disagree with this theory.

The Armley Hippo counts as the most famous hippo fossil in the world.

The name comes from Armley, a district in Yorkshire, England, where workmen discovered the fossils in 1850. Its fame comes from how it first attracted public awe and interest in the 1850s. At the time, people thought hippos could only live in tropical areas, but the Armley Hippo showed that hippos had once lived in Europe.

This fame led to the fossils becoming a museum exhibit, and would only grow from there. In particular, it first became exhibited in an incomplete and unassembled set, just a pile of bones on a table. Later on, as more bones were rediscovered, scientists reassembled the fossil and mounted them on a stand. This fame endures to this day, even with continued discoveries of more hippo fossils in Northern Europe.

Ivory, tusk
Image from Wikipedia

Hippos today face various threats to their future.

Much like pygmy hippos, the biggest threat to the hippos’ future comes from the loss of habitat caused by human development. Humans also hunt hippos, not just for their meat, but also for their tusks, which grow long and hard. This makes them very valuable as sources of ivory. Despite attempts to control or even ban the practice, nearly 13,000 hippo tusks get traded every year as of 2018. Of those, 90% go to Asia, where they enjoy widespread demand for use in traditional craftsmanship and handiwork.