World’s Largest Mouth

Written by Nilani Thiyagarajah
Published: September 18, 2022
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The way that organisms function is fascinating on every level. Looking at how all of the body parts of a complex animal work together, for example, can be absolutely amazing. Sometimes, we might want to take a look at just one body part and how it works. For example, we might want to look at animals with extremely large mouths. How does having this large mouth benefit them? Also, how big is the world’s largest mouth? Read on to find out all about the animal with the world’s largest mouth!

The Animal with the World’s Largest Mouth

A bowhead whale breaches off the coast of western Sea of Okhotsk

Bowhead whales have a massive mouth which can be 16 feet long and 8 feet wide

©Olga Shpak / CC BY-SA 3.0, via Wikimedia Commons – License

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The animal with the world’s largest mouth is the bowhead whale (Balaena mysticetus). This mouth can be up to 16 feet (5 meters) long, 12 feet (4 meters) high, and 8 feet (2.5 meters) wide. The whale’s tongue alone weighs about 1 ton, or 900 kilograms.

Almost all bowhead whales live in Arctic and subarctic waters. They have developed many adaptations to life in icy water, including a layer of blubber that helps with insulation and can be up to 1.6 feet thick. The bowhead whale is the second largest animal on Earth – they can weigh up to 200,000 pounds and be up to 62 feet long. Only the blue whale is larger.

The bow-shaped skull of this whale can be more than 16.5 feet long, which is about a third of the body length of the animal. This allows enough room for its enormous mouth, which is about the size of a garage!

How the Bowhead Whale Uses Its Mouth

The bowhead whale’s mouth contains two racks of baleen plates that they use as a filter system to ingest their food; their diet mostly consists of marine invertebrates.


Surprisingly, even though bowhead whales have such gigantic mouths, they don’t bite their prey with enormous sharp teeth. In fact, they don’t even have teeth! They are baleen whales, which means that they use a filter-feeding system to consume their food. In their mouths are huge sheets of bristles, resembling the teeth of a comb, called baleen.

Every bowhead whale has two racks of baleen plates that are located on each side of the upper jaw, pointing downwards. Each of these racks has approximately 330 individual plates of baleen.

The shortest plates of baleen are located in the front and back of the mouth, and the longest ones are in the middle of the rack. These plates are typically up to 13 feet (4 meters) long and are made up of a substance similar to many animal horns. The inner surfaces of these plates have long fine threads that basically act like a filter. They pull food out of the water for the whale. Basically, the bowhead whale feeds by swimming with its mouth open, filtering food through baleen plates, which act like a sieve for food.

Bowhead Whale Feeding Habits

Bowhead whales will use their enormous mouths to feed at any depth within the water. It can be at the surface or on the sea floor. They feed under the ice as well.

Typically, these whales feed as individuals. However, they have been observed feeding in groups as well. Because the body is not particularly streamlined and the head is very large, they may be able to obtain more food by filtering the water while swimming slowly.

Bowhead whales primarily feed on zooplankton, which is called krill. This includes invertebrates that are similar to shrimp, such as euphausiids and copepods. Although marine invertebrates make up the vast majority of their diet, they will sometimes ingest small fish as well.

According to scientists, the average bowhead whale needs to eat approximately 100 metric tons, or more than 220,000 pounds, of crustaceans on an annual basis. They eat up to two tons of food per day.

The Terrestrial Animal with the World’s Largest Mouth

Strongest animal bite – hippopotamus

The largest mouth on a terrestrial animal belongs to a


; they can open their jaws to almost 180°.

© zengin

Even though the world’s largest mouth belongs to the bowhead whale, the world’s largest mouth on a terrestrial animal belongs to the hippopotamus (Hippopotamus amphibius). Hippopotamuses can be found in zoos all over the world, but they are native to Africa.

Even though hippopotamuses are adapted for life in water and are often found in lakes and slow-moving rivers in Africa, they are considered to be terrestrial animals. What’s particularly impressive about the mouth of the hippopotamus is how wide they are able to open them. The hippopotamus can open its jaws to almost 180°! In an adult male hippopotamus, this means they can open their mouths to about 4 feet (1.2 meters) wide.

How the Hippopotamus Uses Its Mouth

Aggressive Animal: Hippopotamus

The hippopotamus doesn’t use its sharp teeth and ability to open its mouth wide to eat, but instead for self-defense.

©Karel Bartik/

Interestingly, the hippo’s ability to open its jaws this wide doesn’t have to do with the feeding process. These animals are herbivores and typically don’t eat anything other than plants, such as short grass. They don’t even use their teeth to cut the plants, instead cropping the plant matter with their stiff, wide lips. Their lips are two feet wide.

Instead, hippos use their large mouth and teeth primarily for self-defense purposes. They have very sharp canine and incisor teeth, which continuously grow during the lifetime of the hippo. These teeth can grow to be up to 20 inches long.

In order for these teeth to be maximally effective during fights and for self-defense purposes, the hippopotamus needs to be able to open its mouth very wide. Female hippos have smaller teeth than males on average. They don’t often become involved in territorial disputes. However, self-defense is necessary for them, as they do need to be able to protect themselves from herd competition and predators, such as crocodiles.

Hippopotamus Feeding Habits

Typically, hippopotamuses will feed on patches of short grass that are near bodies of water. Sometimes, they will need to travel long distances to find food. They have an acute sense of smell, which helps them sniff out plants to eat. They also hear very well, allowing them to hear the sound of fruit falling from trees.

Hippos consume about 88 pounds of food daily on average. This is between 1% and 1.5% of their total body weight, which is actually a fairly small percentage compared to other mammals. Hippopotamuses are relatively very sedentary unless they are eating, which allows them to conserve energy.

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The photo featured at the top of this post is © Olga Shpak / CC BY-SA 3.0, via Wikimedia Commons – License / Original

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