Sharks

Sharks

Introduction Sharks have lived in the world's oceans for more than350 million years. They were even around before dinosaurs walked on Earth. There are more than 350 kinds of sharks. They can be found from the equator to the poles and from shallow seashores to the deepest waters. Sharks are some of nature's most successful hunters.

Sharks are fish. But unlike most other fish, sharks have no bones. Shark skeletons are made of cartilage, which is the same material that gives human ears their shape. Unlike most fish, sharks have rough skin. The closest relatives of sharks are skates and rays, which are flat, diamond-shaped fish.

Sharks have an excellent sense of smell and are able to see well in poor light. They are especially sensitive to the sounds and movements of injured animals Sharks can even sense the tiny bits of electricity that are produced by all living things. Sharks can sense fish buried under the sand on the ocean floor.

Physical Description Sharks come in many sizes. Some dogfish sharks are only a few inches long. The whale shark is the largest fish in the world. Most sharks have powerful, streamlined bodies to help them catch their prey.

Most large sharks have few natural enemies. Many sharks are protected by camouflage patterns that help them blend in with their surroundings. They are dark on the top and pale on the bottom. Some sharks, called swell sharks, protect themselves from attack by puffing up their bodies with air or water. This behavior makes them appear larger and helps to keep predators away.