You might remember being told as a child to chew your food properly, but maybe you never wondered why you do it.
Many animals chew food as a part of eating, but some others don’t. Cows chew food, spit it up and then chew it again! Dogs tear into a piece of meat, but then swallow it with very little chewing, and snakes are well known for swallowing their food whole.
But what about sharks – Do sharks chew their food?
The short answer is no. Most sharks don’t have the teeth or the jaw muscles to really chew their food. However, some sharks have specialized mouths for breaking open shellfish, which could perhaps be considered a form of chewing!
As usual, the short answer isn’t very helpful, so let’s go into the topic in a little more detail.
Why do some animals chew food?
Many animals chew food before swallowing it, including you! You might not know it, but as soon as your food enters your mouth, it has begun the digestive process.
In fact, it could be argued that the digestive process starts even before that: when you see or smell good food, your mouth starts salivating. This saliva is home to various digestive enzymes that help to break down certain foods like carbohydrates.
The food all animals eat is comprised of long chains of molecules. Proteins, fatty acids, carbohydrates, etc. These molecules are of no use to us in their natural form, so our bodies break them down into their component pieces, absorb them, and then reassemble them into the long chains of molecules we need.
Animals chew food because it’s the first stage in breaking down these complex molecules into smaller pieces.
Saliva is a digestive fluid that chemically breaks down some carbohydrates into their sugary building-blocks.
In animals that chew, teeth act as mashing devices to physically break up their food and work the digestive fluids into the material. It sounds kind of gross when you put it like that, but it’s something you’ve been doing every day for your entire life!
Why do some animals swallow their food whole?
Now you might be wondering, If chewing is so great, why don’t all animals do it?
There are a few reasons why some animals have evolved to swallow their food whole:
- Firstly, chewing is hard work! It uses large, powerful muscles and takes quite a long time, so animals who need to conserve energy might prefer to let the stomach juices do the work.
- Secondly, the saliva typically breaks down carbohydrates and fats, but less-so proteins. The delicate, meaty tissues of the mouth are mostly made from protein, so having chemicals that break down proteins in your mouth might be an issue! Have you ever eaten so much pineapple that it makes your mouth sore? That’s a protease – an enzyme that breaks down protein! Typically, the body leaves that protein digestion to the powerful chemicals in the stomach.
So, an animal that primarily eats meat might not get as much use of chewing its food as one that eats grass (or cakes). Instead, they might send a proteinous meal into the stomach, which is well-protected against proteases by a mucosal layer.
- Thirdly, animal dentition (tooth arrangement) can be specialized to catch and hold prey items and may not lend itself much to chewing. If you think about human teeth, you’ll notice the ones at the back are flat and work well to mash up the food. Those are chewing teeth. Since we don’t have to hunt down and catch a burrito with our teeth, we’re not equipped with the pointed, grabbing teeth that a shark or a tiger has.
So how does this apply to sharks?
Well, sharks eat other animals, which are made up mostly of proteins. Many sharks need to conserve energy for hunting, and they have scary-looking pointed teeth for catching and holding onto prey items.
All the clues point to sharks swallowing food rather than chewing it.
How do Sharks Jaws Work?
You may already know that shark fossils aren’t easy to come by. Usually, all that remains of a shark after it dies are its teeth and sometimes its jaws. This is because, in place of hard bone, sharks have cartilage for a skeleton.
But what are sharks’ jaws made of?
The jaw, too, is made of cartilage, but as the shark ages, it becomes calcified and hardened to help transmit more of the shark’s impressive bite force into its prey.
Even with calcification, a shark’s jaws are exceptionally flexible.
Your upper jaw is fixed to your cranium (the part of the skull above the jaw), meaning that for you to bite, you can only move your lower jaw. And this lower jaw, the mandible, is fused at the chin, so you can’t really open your mouth very wide either. For sharks, neither of these hindrances applies!
A shark’s upper jaw is not fused to the cranium, so it can project forward as the shark attacks and allows the shark to open its mouth wider.
The dislocated and flexible lower jaw also provides added range of motion for opening the mouth wide for that extra-large chomp.
As you can see, a shark’s jaws are pretty specialized, but what about its teeth?
How do Shark teeth Work?
When you think of a shark, you’re probably picturing something large and scary, like a great white or a tiger shark. But sharks are exceptionally variable in their morphologies (shapes and sizes) and have a range of different prey items.
What you eat determines the shape of your teeth!
If you’re gnawing on sticks or grass all day, you’re going to have big old flat teeth for grinding down plant material like a cow or a panda.
If you’re snapping up fishes with your mouth, you’ll want long, backward-pointing spines for teeth like a fork to grab the wriggly little critters.
If you’re a big shark that eats mammals like seals, you want to be able to cut through heavy flesh and blubber with serrated, triangular teeth.
There are also tiny sharks that live in the sand and eat shellfish, such as the adorable Port Jackson shark. These need flat bony plates for teeth that are used to break up the shells of their prey. You might consider this a form of chewing (now you see why the short answer isn’t much good).
Sharks, unlike most animals, typically have rows of teeth that continually fall out and are replaced by new ones. This form of regeneration is due to special stem cells in the shark’s jaw called dental lamina.
So, shark teeth and jaws come in all shapes and sizes, but there’s one kind of shark whose jaw is so big you can fit eight people inside it! Let’s take a look at some of the largest jaws in the shark world, ever.
Sharks’ Jaw Sizes
- Bull sharks are formidable hunters with giant, triangular teeth and an even stronger bite than a great white! The largest of these powerful sharks have a jaw size of at least 20 inches.
- Tiger sharks have very special teeth among sharks. These are very large sharks that eat almost anything (car tires and license plates have been found in their bellies!), and their teeth are curved and serrated like a circular saw for cutting out chunks of prey. These jaws can be upwards of 26 inches across in larger specimens.
- Great White sharks are the only existing predatory shark that’s bigger than a tiger shark, and has teeth that are up to 2.1 inches long! Teeth this size need a big jaw, and the great white owns one that’s more than 36 inches wide.
These are three huge sharks with equally impressive mouths! But there’s one shark so huge that it could swallow any of these previous contenders whole…
The now-extinct Otodus megalodon or Megalodon shark was one of the largest predators ever to have lived in the oceans.
All we know about it comes from fossils of its jaws, which look almost exactly like the jaws of a great white but are so large, it’s estimated to have been three times as long and about thirty times its mass. Megalodon jaws have been found that reach up to 132 inches wide!
This shark died out about two million years ago, possibly due to the reduction in global temperatures of the time and the loss of its prey.
Most sharks don’t need to chew their food.
If they need to take a bite out of something big like a seal, they shake their heads, and the serrated teeth cut out a chunk for them to swallow whole.
Other sharks crush shellfish or crabs with plated bony protrusions in their mouths to break open their shells and suck out the tasty goodness inside. Sharks cover a huge marine domain and are extremely diverse, with specialized teeth and jaws that help them eat a multitude of prey items. But in most cases, they leave the chewing up to the mammals.