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sharks are among the most notorious and feared predators in the world, living in every ocean and a little rivers. They are often known as ‘living fossils’ because they have roamed the oceans over 400 million years, meaning they were there even before the dinosaurs. Despite how long they have been around, there is still more to learn about them. There is one question that often comes up when we talk about sharks, and that is whether they have bones or not. Something as powerful and ferocious as a shark must have bones, right? Join us as we learn all about sharks and find out if they really have bones.
Do sharks have bones?
Many animals have a skeleton that is made of bone and it gives their body shape and strength. So, since sharks are one of the most powerful predators in the ocean and an iincredible bite force, it would be easy to assume that they must have tough bones. Sharks are of the class though Chondrichthyes which means “cartilage fish”, as opposed to Osteichthyes who are bony fish. They are also from the subclass Elasmobranchii which includes everything sharks, shine, to skate, and sawfish. Since sharks are cartilaginous fish, they have a skeleton made of cartilage instead of bone. They don’t even have a single bone in their body!
Cartilage is a tissue that is softer and more flexible than bone. Although sharks have a cartilaginous skeleton, it is still tough and does exactly the same job as a skeleton made of bone. It gives their bodies shape and structure and protects their organs.
Different parts of their bodies are made of different strengths of cartilage and some areas are more flexible than others. Areas that need more protection are made of calcified cartilage that has been calcified by calcium salts, making it much, much tougher. So shark heads are made of calcified cartilage to protect their brains. Parts of their jaw are also made of calcified cartilage (like their jawbone), while other parts (like their snout) are made of softer cartilage. This allows the shark to have the benefit of a stronger skeleton in the areas where they need it most, while still taking advantage of all the other benefits that come from having a cartilaginous skeleton.
What are the benefits of a cartilage skeleton?
Having a skeleton made of cartilage rather than bone is actually a major advantage for sharks and is one of the reasons they are such capable and powerful predators. Cartilage is much lighter than bone, which is important because sharks don’t have a swim bladder. Instead, they must rely on their large oil-filled liver to provide them with buoyancy. Therefore, a really heavy skeleton would be a big disadvantage for them. Because cartilage is much more flexible than bone, sharks can also swim quickly and make quick turns when chasing prey.
Another advantage of having a cartilaginous skeleton is that it makes the shark’s jaw much more flexible. This means that they can open their mouth much wider than if they had a bone jaw. Because they can open their mouths further, they can exert much more downward force in their bite. This is why sharks have some of the greatest bite forces and make them some of the most ferocious predators in the ocean. Shark snouts, however, are made of particularly soft and flexible cartilage. This means that their muzzle can act as a bumper and take heavy blows without taking a lot of damage.
So what are shark vertebrae like?
Sharks are classified as vertebrates, meaning they have a backbone. But how can they have a backbone if they don’t have bones? The truth is that an animal does not have to have a backbone of bone to be a vertebrate. Sharks have a spine made of cartilage, just like the rest of their skeleton. It protects their spinal cord in exactly the same way as one of bone. This is because the cartilage that forms the shark’s spine is calcified. Because the cartilage is calcified, it is strong enough to provide the necessary protection for the spinal cord.
Did ancient sharks have bones?
As we mentioned, sharks have been around for a very long time and in that time they have evolved a lot. But, did? prehistoric sharks also have cartilaginous skeletons, or did they really have bones? The key to finding the answer is by looking at the fossil record. The earliest shark fossil record is a pair of scales dating back 450 million years ago. Then there are some shark teeth from 410 million years ago. In fact, all the way through the fossil record, it’s just shark teeth, dermal denticles, and vertebral centers (dorsal fins) — no bones. Therefore, since no fossilized shark bones have been found, it’s pretty safe to say all that sharks — and even their earliest ancestors — have had cartilaginous skeletons instead of bones.
Cartilage is not well fossilized because it is much softer than bone and breaks down quickly. However, some cartilages (such as parts of the jaw, vertebrae and dorsal fin) are calcified, making them much tougher. Because this cartilage is much harder, it can be fossilized, although it is still very rarely found.
Shark teeth are the most fossilized part of sharks. Aside from being literally the hardest part of a shark (made from 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 huge, huge numbers of shark teeth fallen to the ocean floor over millions of years. This greatly increases the likelihood of them becoming fossilized compared to the dermal denticles and dorsal fins.
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