Sharks move through the water with the help of their tail fins. The body of a shark is light as it is made of cartilage and not bones. It has a perfectly streamlined body. Its dorsal fins help it steer through the water.
The shark uses its forward momentum to keep swimming. A shark has the ability to change the angle of its fins to alter its direction through the water. A shark must swim constantly or else it sinks to the bottom. Unlike other fish, a shark does not have a swim bladder, an organ that provides buoyancy to other fish. Sharks can swim at great speed and turn quickly when needed.