Shark

Sharks are fish with special bodies. They have skeletons made of cartilage instead of bone. Cartilage is the bendy stuff in your ears and nose. Sharks have five to seven holes on each side for breathing underwater. These holes are called gill slits. Their fins are shaped differently than other fish fins.

Sharks have been swimming in our oceans for a very long time. The first shark-like animals lived about 450 million years ago. That was long before dinosaurs walked on Earth. Modern sharks like the ones we know today appeared about 200 million years ago.

Sharks come in many different sizes. The smallest shark is called a dwarf lanternshark. It is only about as long as your hand. The biggest shark is the whale shark. It can grow as long as two school buses parked end to end. Sharks live in oceans all around the world. Most sharks live in salty ocean water, but a few types can live in rivers too.

Sharks have special skin covered with tiny bumps called denticles. These bumps protect sharks and help them swim faster. Sharks also have many teeth. When a shark loses a tooth, a new one grows in its place. Some sharks are hunters that eat other fish and animals. Other sharks are filter feeders. They eat tiny creatures called plankton by straining water through their mouths.

Sharks are important animals in our oceans. But people catch many sharks for food or for their fins. Too many sharks are being caught. Since 1970, shark numbers have dropped by more than half. We need to protect sharks so they can survive.