Hippo Mouth: Size and Facts

Written by Colby Maxwell
Published: January 13, 2022


Hippos are some of the earth’s largest land animals. Their name derives from Greek when they were called “river horses,” but “river cows” might have been a better description. These silly-looking yet ferocious animals are in zoos and coloring books everywhere, making them one of the most famous creatures around. As such, people want to know more about them and what exactly makes them special. Let’s take a look and learn about hippo mouths: their size and facts.

What does a hippo mouth look like?

Hippo Mouth: Size and Facts
Hippos’ mouths have large gums, sharp canines and incisors, and molars for chewing.

Hippo mouths are often the last thing that animals see if wandering too close! Thankfully, we can learn about them from a distance. Let’s take a look at a hippo’s mouth and see what it looks like.

As one of the largest in the animal kingdom, it’s no wonder that their mouths are built to match. Generally, the first thing that people notice is their teeth. Hippos have three sets of teeth: incisors, canines, and molars. The most noticeable ones are the incisors and molars as they are specially adapted to stick out from their mouths like weapons.

Aside from their teeth, we can see their gummy lips and interior. Hippo lips are specially adapted to be large and bony. Per day, they need around 100 lbs of food to keep their weight up, and all of it is from vegetation. Since their days are almost exclusively spent foraging the river banks and bottoms for plants, their lips have adapted to allow them to grasp and pull. With their immense strength and special lips, hippos can pull even deeply rooted plants out of the mud to eat.

When a hippo opens its mouth, one of the most distinctive elements you can see is its orbicularis oris muscle. When their mouths are closed it’s not visible, but it’s actually what allows them to open their mouths so wide. The muscle is on the inside of their cheeks and can unfold (similar to an accordion) when stretched. This allows them to open their mouths wide without hurting themselves.

How big is a hippo mouth?

Hippo Mouth: Size and Facts
Hippo mouths can open 150 degrees, up to four feet total.

Image CreditKarel Bartik/Shutterstock.com

Hippos are known for their size, and their mouths may be their most defining characteristic. Although the blue whale holds the top spot for the largest mouth on earth, the hippo may just take the cake as the largest mouth on land.

Generally, hippo mouths measure 2 feet wide (from left to right) when closed. It’s when they open it, however, that it really gets big. Hippos can open their mouths 150 degrees, essentially a flat line from top to bottom. This is often used to display their teeth to a threat, but it also happens when they yawn. At full stretch, hippo mouths can measure 4 feet tall, enough for a toddler to stand up in.

Their special muscle (the orbicularis oris muscle) unfolds when they stretch their mouth, allowing them to get almost perfect rotation. For comparison, a human jaw can only stretch 26 degrees from a closed position. That means that a hippo is able to open its jaws nearly six times wider than a human. Take a look at a hippo mouth while it’s opening to see this strange (and cool) muscle at work. It’s the key to a hippo mouth!

How strong is a hippo mouth?

Hippos are some of the strongest animals on earth and resultingly, have one of the strongest mouths on earth. When you combine that strength with their immense size, it’s no wonder that hippos are responsible for the majority of animal deaths in Africa.

It’s generally accepted that hippos have a bite force of 1,827 psi. The figure was measured while looking at hippo bite victims in a medical lab, so it’s reasonable to trust it. This bite force is truly astonishing and is around 10 times the strength of a human. While it may feel like a hippo should be more than 10 times the strength of a human (in terms of bite force), it’s important to remember that hippos are exerting this force across a surface area that is many, many times the size of humans. In relative terms, it means that a hippo’s mouth is hundreds of times stronger than a human’s.

There is a common belief that a hippo could “bite a crocodile in half,” but it’s not really true. It’s better to think of it as hyperbole, although there is some truth to the underlying claim. Hippos and crocodiles do share the same territory in Africa, and that often results in fights. There have been reports (and likely videos) of hippos picking up a large crocodile, biting its back (and likely breaking it), and tossing it aside like it was nothing. Was it a clean “bite through the back”? No, but the end result was the same.

Hippo teeth

Hippo Mouth: Size and Facts
Hippo incisors can reach up to 16 inches in length.

Image CreditVINCENT GIORDANO PHOTO/Shutterstock.com

There are three sets of hippo teeth that we generally look at: canines, incisors, and molars.

Canines and incisors are the long teeth that we generally consider as “tusks” at the front of an animal. In humans, canines are the sharp pointy teeth at the corners of your mouth, and the incisors are the front four teeth. In hippos, these teeth have evolved to form long and dangerous weapons used for self-defense.

Their incisors (the two front teeth on the top and bottom) can grow to 1 foot 4 inches. Their canines (the front teeth on the outside edges of their mouths) can grow up to 1 foot 8 inches. The teeth never stop growing and self-sharpen every time they close their mouths. Additionally, their lower teeth grow larger than the top ones.

Hippo molars aren’t as imposing as the other teeth, but that’s for good reason. Molars are designed for chewing plant material and not for defense. For hippos, their molars allow them to process the large amounts of plant material they take in each day.

Do hippos have tusks?

Hippos do have tusks, namely their incisor and canine teeth. They never stop growing and sharpen themselves. The tusks are used for self-defense, mostly when it comes to other hippos in their territory.

What is hippo ivory?

Hippos do have ivory, but it is often considered inferior to other forms (such as in elephants). It’s harder and yellower than elephant ivory, making it harder to carve and visually less appealing to some. Still, hippo ivory is a business model in parts of Africa, mostly as a function of tourism.

//
// //
//// //