Skeleton, Tail, Fins

Sharks have no bones. Their skeleton is comprised of elastic like material called cartilage. Most species bodies are rounded similar to a torpedo, which aids them in swimming. Their tails are crescent shaped which helps to propel them through the water. The upper portion of their tail is longer than the lower and the pectoral fin (the one on their back) is used to lift and balance their body.

Sharks do not have a swim bladder like other fish and must constantly keep moving from the time that they are born so that they will not sink. However, the shark does have a liver, which is very rich with minerals, filled with oil. Because oil is lighter than water, this assists in keeping them afloat.

The teeth are on the underside of the head except for the whale shark, who's teeth are on the front of the head. Sharks retain several rows of sharp teeth. If an old tooth gets lost or wears down, one from behind it moves up and takes it's place. A shark has grinding teeth, cutting teeth or pointed teeth. Althought their teeth are on the underside of their head, they do not have to turn over to attack or bite.

Toothlike scales cover their body like sandpaper (yes, it really feels like sandpaper). The also have gills, but they have 5-7 slits on each side of the head. The water passes through the slits and over the gills. After the gills remove oxygen sharks rely on their swimming to get the water through their mouths and over the gills. This in another reason that sharks are constantly moving.