Shark Anatomy
Shark anatomy is different from that of other types of fish. They have major organs, such as a heart, liver, pancreas, and stomach in common, but when it comes to parts of the anatomy such as fins, gills, teeth, nostrils, eyes, etc., there are many different variations. Shark anatomy is designed to make them sleek, fast, and adept at hunting down prey.
The first big difference between sharks and most fish is the fact that a shark has no bones. Instead, their skeleton is made up of cartilage, which is more flexible and lighter than bone. The only other fish with cartilage instead of bones are rays and chimeras. Most fish have an air bladder which allows them to say afloat but a shark, being lighter, has no need of one.
Bony fish have one gill on each side of their heads which enable them to breathe. As the gills pass through water, oxygen is absorbed into the blood. Shark anatomy is a little different. Instead of one gill on each side of their head, sharks have five to seven. Some sharks have small holes behind their eyes that also work the same as small gills. These are called spiracles, but have disappeared on certain species of sharks. Sharks have a nose but they do not use it at all for breathing, only for scents.
Fish have scales on their skin but sharks do not. They have tiny teeth that are called denticles. These help to protect the shark but they also channel water over its body to help it move faster. A shark’s normal teeth are very sharp. They are not used to chew their food but they will tear apart any prey that cannot be swallowed whole. The fact that most food is simply swallowed is why the stomachs of many sharks contain items like license plates and gas cans.
Fins also help a shark to move through the water. They are quite rigid. Depending on the kind of shark there can be up to five different types of fins. Pectoral fins are underneath the shark and help give it some thrust when swimming. There are pairs of pelvic and dorsal fins, used for stabilization. Some sharks have an anal fin but some do not. This is also for stability. All sharks have a tail fin (caudal fin) which propels them forward through the water.
One part of shark anatomy that is very unique are organs which have been named Ampullae of Lorenzini. Ampullae were jars of clay that people in the time of the Roman Empire used to store oil, grains or food. These organs are pores that lead to canals which are filled with a jelly-like substance and they are used to sense an electrical field. Every living thing produces electrical charges and these organs sense the charges so that the shark knows immediately if another creature is in the water. The Ampullae of Lorenzini are located in various places around the head of the shark. They are often referred to as lateral line canals.