Humans have 206 bones. What about sharks? How many bones does a shark have?
Sharks have no bones. Unlike vertebrate animals and humans, the skeleton of a shark is not made of bones. Instead, it is made of connective tissues and cartilage, which are the same in our ears and nose.
Read on to learn more about how many bones a shark has.
How Many Bones Does a Shark Have?
Sharks have zero bones. Unlike humans and most animals, a shark’s body has no bones. A shark is an elasmobranch, which means that it has cartilaginous tissues. These are the tissues in the human ears and nose.
While sharks have no bones, it is still possible for them to fossilize. As they age, calcium salts deposit in their cartilage. As these deposits harden, they feel as solid and heavy as a bone, even if it is just cartilage.
A common misconception about sharks is that their teeth are bones. Their teeth are made of dentin, a calcified tissue. A solid enamel shell surrounds this tissue, making it harder. This is what gives teeth a similar structure to a bone.
Because the cartilage is soft and flexible, you cannot preserve it the same way as a skeleton. For this reason, many experts do not have an idea of what the body structure of the early sharks is.
Even if a shark’s body is made up of cartilage, it does not mean that they are all the same kinds. Some cartilage is denser than the others, depending on the specific part of the body where they are.
The backbone and jaws are parts of a shark’s body with weak cartilage. They do not have to support the weight of their body, so they are not as dense. Its rostrum or beak, and snout, also have weaker cartilage. The denser cartilage is on the skull.
If sharks have bones, it will weigh them down, making them sink. Unlike other types of fish, a shark does not have swim bladders. It needs to be as lightweight as possible so that it can swim and float.
Do Sharks Have Vertebrae?
Even if sharks do not have bones, they have vertebrae. They have a spinal cord and a backbone, which makes them like humans. However, these are technically not made of bones but soft or connective tissues. Even if you hug them, which is not recommended, they will feel squishy because of the bones’ absence.
Watch the short video below to further understand why sharks have no bones:
Differences Between Cartilage and Bone
From their structure to functions, bones and cartilage are different in many ways. This section will walk you through some of their most notable differences between cartilage vs. bone:
The structural composition is one of the biggest differences between the two. Bones are inelastic and hard. They are tough organs that make up a vertebral skeleton. On the other hand, cartilage is elastic and soft. They are flexible tissues that can become harder over time as a result of calcium salt deposits. This is why shark fossils look like bones, but they are just hardened cartilage.
Bones will protect your body from mechanical damage, provide a shape or framework, and help in the body’s movement. On the other hand, cartilage supports respiratory tract functions, doubles as a shock absorber, and maintains flexibility.
Another main difference between cartilage and bone is density. Bones are denser than cartilage. Its cartilage has half the density of bones. Because of this, cartilage is lighter, which allows sharks to become more flexible and move faster. It can swim quickly without wasting too much of its energy.
Bones are denser, but it does not mean that cartilage is weak. The largest shark weighs 47,000 pounds, and its cartilage supports its body. This shows how strong the skeleton is despite not having bones.
The Anatomy of Sharks
Besides talking about how many bones in a shark, this article will also talk about its anatomy. Below are the most important parts of a shark’s body and its functions:
As we have earlier mentioned, a shark’s skeleton is not made of bones but cartilage. Despite being soft and made of connective tissues, the skeleton is a strong material. It is lightweight but supports the body of the shark, which makes it buoyant. Even if it does not have a swim bladder, the skeleton allows it to float in the water.
From afar, a shark’s skin may seem smooth. However, when you touch it, the texture is similar to sandpaper. It has dermal denticles or placoid scales with an enamel cover. The structure of the skin is similar to teeth. They are pointing backward to reduce drag, allowing the shark to swim fast despite being heavy.
Instead of being permanent in its jaw, a shark’s teeth are in a membrane that looks like a conveyor belt. When the shark matures, this membrane moves forward. It replaces the front teeth. The number, appearance, and shape of teeth will vary, which is also one of the best ways to identify shark species.
The teeth are the most common parts that people fossilize. Aside from museum displays, you will also commonly see their teeth as necklace pendants. These teeth are from sharks that have long been dead. Its calcification gives it a solid form, like a bone. The darker the teeth, the older it is.
To stabilize, steer, and propel in the water, sharks use their fins. The fins are made of elastic protein strands. They have a massive dorsal fin that allows them to balance. It is also common for a shark to have a smaller dorsal fin near its tail. Meanwhile, the pectoral fins are for lifting and steering. Along with the tails, the fins let the shark move forward.
Depending on the type of shark, it has a pair of five to seven gills. They are important for proper respiratory function. This is where water passes through when it is swimming. Water drives from the mouth to the gills. This is also where gas exchange happens. It has slits where water will flow.
The eyes are almost the same as what you will find in other vertebrates, except for some modifications. It has tapetum lucidum, which has plate-like and parallel cells. It improves visual signals, especially when the shark is in a low-light environment. Their eyes also have a nictitating membrane, which closes if a shark passes through an object.
The liver is one of the shark’s most important organs, making up 25% of a shark’s total body weight. In other mammals, the liver makes up only 5% of the body weight. A shark’s liver is dense but lightweight, which is also crucial for its flotation. However, liver oil is also the reason why shark exploitation is common. It is a popular ingredient in cosmetics.
Sharks have two muscle groups – white and red. The white muscles use energy from glycogen breakdown. It allows the shark to move swiftly when escaping from danger or catching prey. On the other hand, the red muscles are responsible for breaking down fat. It improves the blood supply so that the shark can swim for a long time.
So, how many bones does a shark have? Sharks have no bones. Unlike humans and vertebrate animals, the skeleton of a shark is not made of bones. Instead, it is made of cartilage and connective tissue, which are the same in our ears and nose.
Other Interesting Facts About Shark
Now that you know that sharks have cartilage instead of bones making up their skeleton, below are other facts you should know:
1. They Have Been Around for Millions of Years
Sharks have a long history of existence. Experts believe that they have been around for over 450 million years. Meanwhile, according to the National History Museum, most modern sharks have been around for at least 195 million years.
2. They Are Popular Tourist Attractions
From the Galapagos Islands to the Bahamas, tourists flock for the sharks and not just for the beaches. It generates up to $300 million in eco-tourism income annually, providing more than 10,000 jobs in over 29 countries.
3. More Than 100 Million Sharks Are Killed Annually
Human activities are threatening the global shark population. They are targets of overfishing. From shark fin soup to cosmetics, sharks are valuable. Aside from destructive fishing, climate breakdown also hugely contributes to the massive annual death of sharks.
4. Its Anatomy Inspires Smart Design
Biomimicry is an increasingly popular practice these days. In a nutshell, it is all about imitating nature’s design, hoping to solve human problems. The anatomy of sharks has been an inspiration to many smart designs, including water turbines and cars.
5. They Are Solitary Creatures
For most of its life, sharks are solitary. They like being on their own, whether they are just swimming or hunting for food. They will not feed in schools, and they do not need other sharks for protection.
6. The Pregnancy Period Is Long
While the typical gestation period is 12 months, it is incredibly long for some species. The pregnancy can take up to three years. Depending on the specific type of shark, some will lay eggs while others produce fully-developed small sharks.
7. Whale Sharks Have Unique Patterns
There are many shark species, but the whale shark is perhaps the most popular. It is also the largest shark, growing up to 18 meters long. They are known for having unique skin patterns, which are as distinct as human fingerprints.
8. They Are Survivors of Five Mass Extinctions
Despite the apparent extinction, sharks are tough mammals. They have already been through five mass extinctions, and that includes one that has killed the dinosaurs. Sadly, with the current threats they face, the shark population is in a continuous decline.
9. Motion Is Limited
While sharks are swift movers under the water, they have limited movement. They are the only fish that cannot swim downward. They cannot even make a sudden stop once they are already moving. If they have to move backward, they have to depend on the pull of gravity.
10. They Rarely Attack Humans
The operative word here is rarely. While there have been several shark attacks in the past years, they are a small number. Even if they are opportunistic feeders, most shark species are not harmful to humans as they would rather prey on fish and other marine mammals.
According to PETA, the chance that sharks will attack humans is one in 3.7 million. There is a higher possibility that you are killed by fireworks or champagne cork than a shark attack. Despite their intimidating size and appearance, sharks are not that scary.
Health Benefit Claims of Shark Cartilage
While it is a subject of global debate and inconclusive studies, a shark’s cartilage is prized for its many benefits. It has several health uses. However, note that evidence is currently lacking, so we do not recommend using shark cartilage for any of these purposes.
Some people claim that shark cartilage acts as an angiogenesis inhibitor. This means that it stops the formation of new blood vessels. By cutting off the blood supply, it may ward off cancer cells.
Another common assertion about shark cartilage is that it can boost your immune system. Thus, it can manage certain diseases, such as osteoarthritis, psoriasis, and bowel inflammation.
Conclusion – How Many Bones in a Shark?
Sharks have no bones. Even their jaws and skulls do not have bones. Unlike humans, sharks do not have a rigid and solid skeleton that gives shape to its body. Instead, its cartilage is made up of soft and connective tissues – the same tissues present in the human ears and nose.
Compared to bones, cartilage is softer, lighter, and more flexible. Without the density and weight, and bones, sharks will be moving quicker in the water. More importantly, they will do so without using a lot of their energy.