There are 465 known species of sharks that display different physical characteristics. Most are identifiable by their darker upper sides that blend with the water above and their white or lighter-colored undersides that blend with the sea below, in addition to their fins, side gill slits and rows of sharp teeth. Shark skeletons are composed of cartilage, a light and flexible tissue.
Great white sharks are the largest predatory fish found in the world. They usually reach an average length of 15 feet and are known for their slate-gray upper bodies and white underbellies. Great whites have up to 300 serrated triangular teeth and a torpedo-shaped body.
Tiger sharks can be as long as 16 feet and are characterized by their body's dark stripes that resemble the pattern found on a tiger. The blue shark has an elongated and slender body and long pectoral fins. Its top is dark blue, its sides are a lighter blue, and its underside is white. Blue sharks reach anywhere from 6 to over 10 feet in length; however, females tend to be larger than males.
The hammerhead shark is known for its flattened and sideways-extended head that resembles the shape of a hammer. These sharks range anywhere from 3 to 19 feet. They are typically light gray with a greenish tint on top while their bellies are white.