10 Hippopotamus Facts About The River Horses

The hippopotamus proudly holds the world's third-largest mammal title with their enormous bodies and even larger heads. As we all know, they relish their time lounging in the water, a smart move to escape the scorching heat. But wait, there's a lot more beneath the surface to these intriguing creatures. Unravel more as you browse our list of hippopotamus facts below.

Believe it or not, hippos lay claim to their turf uniquely - by tail-flicking their excrement! Not only that, we'll explore their adaptations and behaviors, dispelling myths such as hippos sweating blood. Let's jump straight into all the facts about hippopotamuses you need to know.

Hippos are just one of the many animals that start with the letter h. You can also check out the hippos' closest cousins in our whale facts.

Top Facts About Hippopotamus

1. They are the third largest land mammal.

Hippopotamuses are one of the largest mammals on land. Third to the elephants and white rhinos, adult male hippos–specifically the common hippos–can weigh up to 3,500 kilograms (7,716 pounds). On the other hand, females weigh an average of 1,600 kilograms (3,527 pounds).

There are only two species of hippos: the larger Common Hippo (Hippopotamus amphibious) and the Pygmy Hippo (Choerpsis liberiensis). They live in the rivers, lakes, and swamps of sub-Saharan Africa.

2. The name hippopotamus means river horse.

The moniker "hippopotamus" carries the intriguing weight of its ancient Greek roots. Stemming from "hippo," translating to horse, and "potamos," meaning river, this majestic creature is aptly named the "river horse."

The hippotamus has a long history that dates back millions of years. Fossil records reveal that hippos existed approximately 23 million years ago during the Miocene epoch¹. Throughout history, they have evolved to survive in semi-aquatic habitats.

3. Hippos can sleep underwater.

Surprisingly agile in the water, these semi-aquatic mammals can hold their breath for five minutes or even longer. Hippos' physiological adaptations made this lifestyle possible. For example, their nostrils sit on the highest point of their heads, allowing them to breathe easily underwater. Underwater hippos can shut their nostrils to keep water from their airways. 

They are also buoyant thanks to their fat, which acts as a natural flotation device, allowing them to stay afloat effortlessly. Furthermore, their webbed feet propel and stabilize as they glide through the water. 

Interestingly, hippos spend so much time in their aquatic habitat; they also sleep underwater! Although hippos can rest on land, they spend several hours a day in the water. During this time, they enter a semi-conscious state and remain underwater with only their eyes and nostrils visible above the water.

These river horses might look like gentle giants, but the following fact will say otherwise.

4. They are aggressive and dangerous animals.

Hippopotamuses may seem calm and adorable, but they are one of Africa's most dangerous animals, killing more humans than lions, crocodiles, or other African species. These beasts kill 500 humans annually, higher than the lion's annual mortality rate of 22.

The hippopotamus has a jaw-dropping bite force of 12,600 kilopascals (kPa). This impressive feat of strength puts the lion's bite force at 4,500 kPa to shame. With its formidable jaw strength and sharp teeth, the hippopotamus can effortlessly crush a human body in a single bite². As such, they've also earned a place in our list of the world's strongest animals.

Though these fearsome creatures don't eat humans, male hippopotami (bulls) are incredibly territorial. Bulls battle intensely with other males or humans who trespass into their space.

When you tour Africa's national parks, don't wander into hippo territories; it might be the last thing you'll see.

5. Hippopotamus are vegetarians.

Common hippos eat grasses, young shoots, fruits, and aquatic plants. These nocturnal animals can devour an impressive 80 pounds (36 kilograms) of vegetation in just one night. They usually graze in the water for four to five hours.

Furthermore, their favorite aquatic plants are water hyacinths, reeds, and other floating vegetation in their habitat. They use their broad lips to grip and tear off chunks of vegetation before chewing it with their powerful jaws. Despite being vegetarians, they can also eat other animals and hippos' carcasses.

Explore other humongous herbivores by visiting our elephant facts and gorilla facts.

6. They mate underwater.

Hippos mate in the water during the mating season, which occurs throughout the year. Male hippopotami compete for access to females. Once a dominant male establishes control over a territory or group of females, he mates with receptive females. Mating occurs underwater, with the male approaching the female.

The gestation period for hippos is approximately eight months, although it may vary slightly among individuals. Female hippos usually give birth to one baby hippo on land or in shallow water away from predators. These species reproduce every two years, allowing them sufficient time to care for and raise their young before conceiving again. 

Baby hippos, also called calves, weigh around 55 to 120 pounds (25 to 55 kilograms) and measure about 3 to 4 feet (0.9 to 1.2 meters) long. They are born in the water and can swim alongside their mothers shortly after birth.

Calves start exploring land at around three weeks old but still spend most of their time in the water for safety from predators like crocodiles or lions. The common hippo has a fast growth rate, gaining up to eight pounds (3.6 kilograms) daily during their early months. 

Young hippos become independent from their mothers by three or four years old and either venture out independently or join bachelor groups until they reach sexual maturity.

7. Hippopotamuses stay together in groups called "pods."

Hippos live in groups called "pods" or "bloats," with a male dominant leading the group. Despite having a dominant male, female hippopotamus significantly influence the group. They establish a hierarchy among themselves based on age and size, with older and larger females having more authority.

Female hippos, known as "cows," develop solid bonds and often form subgroups within the larger pod. These alliances provide support for raising their young and maintaining group cohesion. 

Communication is an essential aspect of hippo social behavior. Hippos use vocalizations like grunts, roars, bellows, snorts, and honks to communicate territorial boundaries, aggression, submission, and distress.

8. Hippos don't sweat blood. 

Despite what many people believe, hippos do not sweat blood. The hippo's red "sweat" is simply sweat that acts as a natural sunscreen and moisturizer for sensitive skin. The sweat protects against sunburn and hydrates their skin.

The red color of the secretion comes from pigments called Hipposudoric Acid and Norhipposudoric Acid³, produced by the hippo's body. These antibacterial pigments protect the hippo's skin from infection and harmful microorganisms.

Furthermore, the red sweat also acts as a waterproof agent for the hippo's skin. Interestingly, hippos produce more blood and sweat when out of water for extended periods or under stress.

9. They are keystone species.

As ecosystem engineers, hippos have a massive impact on their environment. Their appetite for plants helps maintain grasslands by preventing overgrowth and promoting new growth. It benefits other hippos, land animals, and herbivores sharing their habitat.

Hippos also have a significant impact on aquatic ecosystems through their dung. Their waste becomes a nutrient source for fish and microscopic organisms. These nutrients promote the growth of algae and other primary producers, supporting a diverse food web.

Check out our bee facts and capybara facts to learn about other keystone species.

10. The Pygmy Hippopotamus is endangered, while the Common Hippos are vulnerable.

The pygmy hippo (Choeropsis liberiensis) is distinct from the commonly known hippos or river hippos (Hippopotamus amphibius). These smaller creatures only weigh between 400 to 600 pounds. The lush forests and marshy areas of West Africa are their natural habitat.

Unlike the larger species, pygmy hippos live a solitary lifestyle in Liberia, Sierra Leone, Guinea, and Ivory Coast. They face threats like habitat loss and hunting.

Meanwhile, the common hippopotamus species also faces challenges in the wild, putting its population at risk. In the last 75 years, the hippo population has decreased by 7-20% because of poaching and loss of habitat. These threatened species have received the "Vulnerable species" classification on the IUCN Red List due to these threats.

Urbanization and agriculture are shrinking hippo habitats, bringing them closer to human activities and making it harder for them to find resources. Poaching is another threat fueled by the illegal trade in hippo ivory tusks. Unlike elephant ivory, hippo ivory is denser and of higher quality, making it desirable for artisans. This industry puts immense pressure on struggling hippo populations and jeopardizes their survival.

Conservation efforts are actively taking place to protect hippos. The African Wildlife Foundation has implemented initiatives that help communities safeguard their agriculture and farmland from grazing hippos. They assist in building protected areas, enclosures, fences, and ditches, which help minimize conflicts between humans and wildlife. 

Spread the word! Share these hippopotamus facts or click on over to our hippo quotes and deepen the collective love for these important river giants.