The Hippopotamus Is Social in Water, Solitary on Land

Did you know the word "hippopotamus" comes from the ancient Greek for "river horse"? But don't let that fool you; this big, lumbering mammal is anything but a horse. In fact, it's one of the most powerful animals living in Sub-Saharan Africa today.

Hippos aren't just lazy river-dwellers lounging around all day; they play a crucial role in their ecosystems. You'll find them spending much of their time submerged in rivers and lakes, helping maintain balance in their environment.

Physical Characteristics

The common hippopotamus, Hippopotamus amphibius, is one of the largest land animals on Earth. Adult hippos can weigh between 1.5 to 3 tons (that's like a small car!), and they can grow as long as 16 feet (4.9 meters).

These massive bodies are supported by surprisingly short legs, which are perfect for lumbering through water but not great for sustained running.

When you look at their massive bulk, it's easy to see why hippos are often thought of as slow. But don't be fooled; they can sprint at speeds of up to 19 miles per hour when needed.

One of the most striking features of a hippo is its hippo teeth, especially the large canine teeth that male hippos use for fighting off rivals. These tusk-like teeth can grow up to 20 inches long and are a big part of what makes hippos such formidable animals in the wild.

Despite their deadly nature, these teeth are not used for hunting, since the hippopotamus is an herbivore and uses its rear molar teeth eat grass.

Hippos have skin that's about 2 inches (5 cm) thick, which helps protect them from injuries and predators. This thick skin also secretes a special fluid that acts like sunscreen, keeping their bodies from drying out when they're out of the water. This fluid is known as "blood sweat" and gives the hippopotamus a brownish-pink coloring.

Subspecies and Pygmy Hippos

There are two main types of hippos: the common Hippopotamus amphibius and the pygmy hippopotamus. While the common hippo is famous for its massive size and river-loving lifestyle, its smaller cousin, the pygmy hippo, is a bit different.

Pygmy hippos are native to the forests and swamps of West Africa, specifically in countries like Liberia and Sierra Leone. They are much smaller, weighing in at around 600 pounds (272 kg), and they are less social than their larger relatives.

These pygmy hippos are also more solitary, spending most of their time in dense forests rather than open rivers. Despite their smaller size, they share many characteristics with the common hippo, including their ability to stay underwater for long periods to keep cool.

But don't conflate the two; while both species share the name "hippo," they lead very different lives.

Moo Deng the Pygmy Hippopotamus

In 2024, we gained a special little celebrity in the hippo world: Moo Deng, a pygmy hippo who has captured the hearts of many.

Born at Khao Kheow Open Zoo in Si Racha, Thailand, Moo Deng represents hope for the future of her endangered species. Pygmy hippos like Moo Deng are ambassadors for their species, helping raise awareness about the critical conservation efforts needed to protect them from extinction.

Thanks to initiatives like habitat preservation and breeding programs, we're seeing positive signs for the survival of pygmy hippos. There's still much work to be done to ensure that future generations will be able to marvel at these unique and wonderful creatures.

Social Habits

Hippos are highly social animals, particularly common hippos, which live in groups called pods or bloats. A pod can include anywhere from 10 to 30 hippos, but in some areas with large hippo populations, these groups can swell to over 100 individuals during mating season.

Male hippos are often dominant in these groups, defending their territory from other males, while female hippos and their calves make up the bulk of the pod.

Despite their social nature, hippos are also highly territorial. Male hippos will fiercely defend their stretch of river or lake from rivals, using their massive hippo teeth to fight for dominance.

On land, however, hippos tend to be more solitary. At night, when hippos emerge from the water to graze, they spread out to cover vast areas of grassland.

Life Cycle

Female hippos give birth in the water, typically to a single calf, after a gestation period of around 8 months.

These calves are born weighing about 50 to 100 pounds and must quickly adapt to their semi-aquatic lifestyle. Baby hippos are able to nurse underwater and are fiercely protected by their mothers for the first few years of life.

Adult hippos can live up to 40 years in the wild, but it's not an easy life. As hippos age, they often face challenges like territorial disputes, scarcity of food, and threats from predators such as crocodiles and lions. However, the most significant threat to their survival comes from humans.

Diet

Despite their massive size and fearsome appearance, hippos rely on a diet of grasses. They'll spend most of their nights munching on up to 80 pounds (36.3 kg) of grass in a single go.

In times of food scarcity, they have been known to consume aquatic plants and, occasionally, hippo meat. Yep, sometimes hippos will scavenge the carcasses of other animals and even engage in cannibalism, but that's pretty rare.

Because hippos spend most of their days lounging in rivers, you might assume they feed underwater. But nope, they actually do all their grazing on land. The time spent in the water helps them conserve energy during the hot African days, which is why they choose to feed under the cover of night.

Environment

Hippos live in semiaquatic environments, meaning they split their time between land and water. In fact, hippos live primarily in the river beds, lakes and swamps of East Africa.

These watery environments are essential for the survival of the large mammal. The cool waters help regulate their body temperature and keep their sensitive skin from drying out. And don't forget: Hippos are fantastic swimmers, able to stay submerged for up to five minutes at a time.

While the common hippo is more widespread across Sub-Saharan Africa, the pygmy hippopotamus is mostly confined to small, isolated patches of rainforest in West Africa. These regions are under threat from human populations, which brings us to a critical topic: human-wildlife conflict.

Hippo Populations' Conservation Status

Both common and pygmy hippos face significant challenges in today's world. Hippo populations have been declining due to habitat loss and poaching.

Humans often view hippos as threats to their crops or settlements, leading to increasing human-wildlife conflict. Additionally, hippos are hunted for their meat and ivory-like teeth, which has caused their numbers to dwindle.

While common hippos are classified as "vulnerable" on the IUCN Red List, pygmy hippos are considered "endangered," with only a few thousand individuals left in the wild. Conservation efforts are underway, but protecting these remarkable creatures will require a concerted global effort.

We created this article in conjunction with AI technology, then made sure it was edited and fact-checked by a HowStuffWorks editor.

Original article: The Hippopotamus Is Social in Water, Solitary on Land

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