Shark Anatomy

The reason why sharks have survived for so long without making a lot of changes is because of their internal and external anatomy. Their external anatomy keeps them streamlined in the water, such as the gill slits, which take in the water around them as the shark moves, and filter in air, and out water. The many many fins help the shark stay moving, such as the caudal, or tail fin, which produces forward movement. The pectoral fins are the other main fins on the shark, which help the shark steer. The top fin, the dorsal fin, helps keep the shark from rolling all over the place. The claspers are featured only on male sharks, helping hold on to the shark during mating rituals. The internal anatomy of a shark keeps it alive and thriving. The most interesting thing about a shark's skeletal system is that it is not made of bone like bony fish and humans. It is made of cartilage, the thing that our ears, noses, and joints are made of. Shark skulls are hardened with some calcium though, which makes it sturdier. This combination makes sharks faster and more maneuverable. Some sharks are even capable of biting their own tails! Having a cartilage based skeleton has its disadvantages, though. Sharks cannot support their weight out of water, so their internal organs slowly crush on top of them.  A shark's circulatory system works about the same as humans, with some slight differences. For instance, bones are what produce the red blood cells needed throughout your body. Since sharks don’t have any bones, they have special organs called the spleen and the Leydig’s organ that do this necessary task. Sharks are cold blooded, which means they lose body temperature in cold water. Some sharks in the Lamnidae family, however, have another special organ called a rete mirabile. This allows the shark to warm essential organs before functioning in cold water. Otherwise, a shark's circulatory system is just like humans.  Sharks are represented in culture as mindless killing machines, when they are actually pretty smart creatures. One little known fact about them is that they can remember the solutions to puzzles for almost a year! You need a big brain to be able to do that kind of thing. Another thing that makes them super smart is that they learn how to do things by watching other sharks do it! That is a very smart thing to do, and we utilize that all of the time in our everyday lives.  A common misconception regarding shark smarts is that they can smell a drop of blood in a swimming pool. While they have an amazing sense of smell, it isn’t that good. Overall though, sharks are pretty smart creatures. The brain of a shark controls the digestive system, which works the same way, just using different tools to do the job. The liver is the shark's largest organ, helping to keep the shark buoyant, and cleaning the blood. Instead of large and small intestines, sharks have a spiral valve, which is a corkscrew shape for maximum nutrient absorption. The gallbladder helps break down fats in the shark's body and synthesizes them. Otherwise, a shark's digestive tract is just like a human being. Everyone needs to breathe, and a shark is capable of doing so without any similarities to humans. Most sharks breathe through RAM ventilation, a method in which when a shark moves, it takes in water flow from the gills and is distributed throughout the body. Some sharks, like the wobbegong shark, have buccal pumps, throat muscles that allow the shark to take in water while staying still. These five major systems help to keep the shark alive and hunting for prey.

This is what a shark’s skeleton looks like. Made with cartilage, not bone.

Image credit: Science connected magazine

Image credit: JawsandGumballFan24

A sharks circulatory system looks very different from humans, but it functions very similarly.

Image credit: JacquelineRae

This is a diagram of a shark brain, labeling the major regions.

Image credit: 9gag

This is how the digestive system of a shark fits and works together

Image credit: Enchanted learning

This is a diagram on how RAM ventilation works in a shark.

image credit: Angelena Mangieri