Are Hippos Friendly? [No, They Are Dangerous]

Photo: Bouke Atema / Shutterstock

In areas where hippopotamuses live, the people there know to stay away. Fishermen take great risks when accessing water sources and must be on alert at all times for the great danger that hippos pose.

Hippopotamuses are not friendly. They are dangerous and known to attack other animals and humans. Hippos aggressively defend their territory and display dominance with their enormous size, long tusks, and wide powerful mouths both in and out of water. They can hide in water with only their eyes and ears above the surface for surprise attacks. Hippos are also aggressive in protecting their young and in mating practices.

This article offers detailed information about why hippos are so aggressive and considered one of the most dangerous animals to encounter.

Hippopotamus Facts

Hippos belong to the Hippopotamidae family as semiaquatic, artiodactyl (even-numbered toed) mammals. They live in and adjacent to water such as swamps, rivers, and lakes, and have four toes on each foot.

There are two species of hippopotamuses:

  • Common river hippopotamus (Hippopotamus amphibious)
  • Pygmy hippopotamus (Choeropsis liberiensis)

Referred to as water cow, river horse, or as pig-like, they do not resemble domestic farm animals. Molecularly they are similar to cetaceans (such as whales and dolphins). 

Hippopotamuses live primarily along rivers and lakes in sub-Saharan Africa. Hippos found elsewhere are due to exportation.

Hippos have hairless, 2-inch thick skin, find refuge in cooling waters in sub-Saharan heat during the day, and consume grasses and fruit when on land when the nights are cooler.

Hippos consume about 88 pounds of food daily, up to 1.5% of their body weight. They primarily eat vegetation such as fruit and grasses but will consume meat. However, they are not carnivorous predators. 

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3 Reasons Why Hippos Are Aggressive

The hippo’s aggressive nature contributes to its successful survival in regard to defense, protection, dominance, and mating.

1. Defense And Protection

A group, or herd, of hippopotamuses, can range from 10 to 30 members, which includes several mature females, a dominant male, and offspring.

Females are just as aggressive as males, especially when protecting their young (calves).

Generally, adult hippos are safe in the water from predator attacks. However, crocodiles can pose a risk, especially to young, ill, or aging hippos.

On land, group hunters such as lions and hyenas can pose a threat to hippos, or the weaker members of their group.

Fishermen boating on water or accessing the water from ashore may be perceived as a threat, and are attacked as a result.

On average, 500 people are killed annually by hippos, whereas lions kill up to 200 people a year. This makes hippos the deadliest land creature.

2. Dominance Over A Herd And Territory

Male hippos, in particular, fight for leadership or control over territories, such as a mudhole or section of water. These fights typically take place in the water. 

Young males or offspring without a herd may be a part of the group, as long as they respect the leader. An angered adult hippo may even kill one of its own.

As males fight for dominance, young hippopotamus can be killed if caught in between them. 

Hippopotamuses mark their territory daily with up to 60 pounds of dung, spinning their tails to fling and spray the defecation around. The dung can be spread up to 32 feet away from their body. 

A large amount of dung sits in the water, which can kill off fish populations. On average, a hippo’s territory is 270 yards (810 feet) in length.

3. Mating

Male (bull) hippos also fling dung to attract females (cows). 

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The dominant male will mate with several females in its group. Approximately 10% of the males have enough territory to acquire a mate, and only about 1 in 10 males will mate with females.  

A male will locate a female in heat by smelling her rear end or drinking her urine. They then isolate themselves in the water and both genders will aggressively clash tusks.

The female will become subdued, and then the male will mount her in the water.

Powerful Physical Characteristics Of The Hippo

The physical characteristics of a hippo’s size, eyes and ears, and powerful mouth and teeth make it an indomitable adversary and lethal creature. 

They also emit loud powerful sounds when fighting, mating, or protecting the herd.  Hippos can move effectively in water, and swiftly on land.

Size: Height And Weight

Hippos are the second heaviest land animal after the elephant. Males weigh more than females. 

A common hippo can weigh from 3,000 to 9, 920 pounds, ranging in length from 10.8 to 16.5 feet, up to 5.2 feet tall at shoulder height. 

A pygmy hippo can weigh 400 to 600 pounds, ranging in length from 4.5 to 6.0 feet, up to 3.0 feet tall at shoulder height.  

The sheer size of a hippo allows it to put a tremendous amount of force behind its attacks.

Locomotion: Density And Speed

Underwater Locomotion

Hippos can’t swim, yet they can move efficiently in water, spending up to 15 hours a day in it, and move about 5 miles per hour (mph) when swimming underwater.

They must keep their skin wet to avoid dehydration. They don’t have typical sweat glands but secrete a “blood sweat”, a thick, red substance to protect their skin from sunburn and dehydration.

The high bone density of the hippo acts with gravity to keep the hippo in contact with the bottom surface under the water. 

Hippos maintain contact with the bottom, propelling and pushing off with a gait much like a gallop. The buoyancy of the water with the movements of the hippo creates forward propulsion

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Land Locomotion

Even though hippos weigh multiple tons, they can run up to 18 mph, faster than humans. 

They can cover short distances in a matter of seconds, maintaining top speeds for about one minute, chasing or charging away any threats to them or their herd.

Eyes and Ears

The ears and eyes of hippos are located on top of their heads, allowing them to submerge almost completely while observing the surroundings. 

They cannot breathe underwater but can hold their breath for up to 5 minutes, closing their nostrils. 

This allows hippos to stealthily surprise and attack any threats. 

Mouth: Teeth, Tusks, Bite Force

Hippos have the largest mouth opening, capable of opening it up to 180°, which translates to a wide gape of 4 feet in an average adult male. 

Hippopotamuses open their mouths wide to show dominance or as a threat posture. 

A hippopotamus has teeth for eating herbivorous plants but also has enlarged canines and incisors that grow continuously. 

These large tusk-like protrusions are in both jaws, growing up to 39 inches (3.25 feet) long. These teeth are not used for eating, but rather for attacking and fighting. 

The bite force of a hippopotamus is 1827.4755 pounds per square inch, offering a powerful bite paired with sharp tusks.  

In Conclusion

A hippopotamus’ powerful mouth, tusk-like teeth, and territorial dominance make them one of the most aggressive mammals on land.

They will attack other animals, such as crocodiles, as well as humans that come into their territory, using their sheer size to propel them. Hippos also defend their herd, especially the calves.

Hippos can move powerfully in water, discreetly hiding in the water, and propelling their weight off of the bottom’s surface, and can run faster than humans on land.

It is best to avoid any contact with and use extreme caution around a dangerous hippopotamus and its territory.

James Ball

James has had a lifelong passion for animals and nature, tracing back to his childhood where he first began fostering intimate knowledge and connection with pet frogs and snakes. He has since honed this interest into a career as a trained Wildlife Biologist, specializing in Biogeography, sustainability and conservation. In addition to his professional pursuits, James maintains an active lifestyle, regularly indulging in outdoor activities such as hiking, and musical pursuits like playing piano and swimming.

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