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Do sharks have bones?

Updated: January 23, 2023

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Sharks are one of the most notorious and feared predators in the world, found in every ocean and some rivers. They are often referred to as "living fossils" because they have roamed the oceans for more than 400 million years, which means they even predate the dinosaurs. However, even though they've been around for a long time, there's still much more to learn. A question that often comes up when we discuss sharks is whether or not they have bones.

So do sharks have bones? Creatures as powerful and ferocious as these must have bones, no? Find out below!

Do sharks have bones?

Many animals have a skeleton made of bones, which gives them their size and gives them strength. So, considering that sharks are one of the most powerful predators in the ocean, and have an incredible bite force, it's easy to assume they must have tough bones. Sharks, however, belong to the class Chondrichthyes , which means "cartilaginous fish," not bony fishes. They are also from the Elasmobranchii subclass, which includes all sharks, rays, skates and sawfish. Since sharks are cartilaginous fish, their skeletons are made of cartilage rather than bone. In fact, the shark doesn't even have a single shark bone in its body!

Cartilage is a softer, more flexible tissue than bone. However, even though sharks have a cartilaginous skeleton, it is still tough and serves exactly the same purpose as a bony skeleton. It gives shape and structure to their bodies and protects their organs.

Different parts of their body are made of cartilage of different strengths, and some parts are more flexible than others. The areas that need more protection are made of calcified cartilage, which has been calcified with calcium salts, which makes it very, very tough. So sharks' heads are made of calcified cartilage so that their brains are protected. Parts of their jaws are also made of calcified cartilage (such as their jawbones), while other parts (such as their noses) are made of softer cartilage. This allows the sharks to acquire stronger bones in the areas where they need them most, while still taking advantage of all the other benefits of cartilaginous bone.

What are the advantages of cartilage bones?

deadliest animals in america
Having flexible bones allows sharks to open their mouths and exert greater bite force


Having a skeleton made of cartilage instead of bone is actually a big advantage for sharks, and it's one of the reasons they're such capable and powerful predators. Cartilage is much lighter than bone, which is important because sharks don't have swim bladders. Instead, they must rely on a large liver filled with oil to provide them with buoyancy. Therefore, a very heavy frame is a major disadvantage for them. In addition, because cartilage is much more flexible than bone, it also allows the shark to swim fast and turn quickly when chasing prey.

Another benefit of having a cartilaginous skeleton is that it allows the shark's jaws to be more flexible. This means they are able to open their mouths wider than if they had a jaw made of bone. Because they can open their mouths wide, they are able to exert greater downward force when occluding. This is why sharks have some of the strongest bite forces around and make them one of the most savage predators in the ocean. However, a shark's snout is made of exceptionally soft and elastic cartilage. This means their noses act as bumpers, absorbing hard hits without taking too much damage.

So what about shark vertebrates?

Sharks are classified as vertebrates, which means they have a backbone. But how can you have backbone without bones? In fact, an animal doesn't have to have a backbone made of bones to be a vertebrate. Sharks' spines, like the rest of their bones, are made of cartilage. It protects the spinal cord in exactly the same way as the spinal cord is made of bone. This is because the cartilage that makes up the shark's spine has become calcified. Because of the calcification of the cartilage, it is tough enough to provide the necessary protection for the spinal cord.

Largest Tiger Shark - Distinctive Features of the Tiger Shark
Even though sharks have no bones, they are still vertebrates because their backbones are made of cartilage


Did ancient sharks have bones?

As we've already mentioned, sharks have been around for a long time, and they've evolved a lot during that time. But if you went back in time and asked the question, "Do sharks have bones?" what would you find? Did prehistoric sharks also have cartilaginous skeletons, or did they really have bones?

The key to finding out is to look at the fossil record. The earliest shark fossil record is a few scales, dating back 450 million years. Then there are some shark teeth from 410 million years ago. In fact, throughout the entire fossil record, there are only shark teeth, dermal denticles, and the center of the spine (the dorsal fin)—no bone. So, since no shark bone fossils have been found, it's safe to say that all sharks—even their earliest ancestors—have cartilaginous skeletons rather than bones.

Cartilage doesn't fossilize well because it's much softer than bone and breaks down quickly. However, some cartilage (such as parts of the jaw, vertebrae, and dorsal fin) calcifies, which makes them tougher. Since this cartilage is much harder, it can be fossilized, although it is still rarely found.

Shark teeth are the most common fossilized parts of sharks. Besides because they're actually the hardest part of the shark (made of dentin, which is harder than bone), it's also because there are so many of them. Sharks usually just replace lost or worn teeth — the old ones just fall out and new ones take their place. This means that over millions of years, a large number of shark teeth fell to the bottom of the sea. Compared with dermal denticles and dorsal fins, this greatly increases the likelihood that they will end up fossilized.


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about the author

For many years, I have been writing professionally, with an emphasis on animals and wildlife. I love spending time outdoors, and when I'm not writing I'll be found on a farm surrounded by horses, dogs, sheep and pigs.

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