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Shark

Adapted from Wikipedia · Explorer experience

A grey reef shark swimming in the clear waters of Kingman Reef in the Pacific Ocean.

Sharks

Sharks are amazing fish that have swum in the ocean for hundreds of millions of years. They are special because their bodies are made of soft material called cartilage, not hard bones like most other fish. Sharks have skin covered with tiny tooth-like scales called denticles. These help them swim smoothly through the water.

Sharks come in many different sizes. The smallest shark, the dwarf lanternshark, is only about 17 centimeters long. The largest, the whale shark, can grow up to almost 19 meters long—making it the biggest fish in the world! Sharks live in all the world's oceans, from shallow coastal waters to deep sea. Some, like the bull shark, can even travel between saltwater and freshwater.

Many sharks are important because they help keep the balance of ocean life. However, many shark species are in danger because of overfishing and the harmful practice of shark finning. Protecting sharks is very important for keeping our oceans healthy.

Sharks have been around for a very long time. The first shark-like fish lived about 439 million years ago. Today, there are more than 500 kinds of sharks. Some well-known sharks are the blue shark, tiger shark, great white shark, and whale shark. Scientists study sharks to learn how different kinds are related.

Sharks have special teeth that grow in rows inside their gums. When old teeth fall out, new ones move forward like a conveyor belt. Unlike most fish, sharks have skeletons made of flexible cartilage instead of hard bone. This helps them stay light and swim easily. Their skin has tiny tooth-like structures called denticles. These help reduce drag in the water and can form patterns like stripes or spots, helping sharks hide. Sharks also use their tails for swimming.

Sharks have strong senses that help them find food and move through the ocean. One of their best senses is smell. They can find tiny amounts of substances, like a small drop of blood in a lot of water. This helps them find food even when it is far away or hidden. Sharks also have good eyesight, especially in dim light. In addition to smell and sight, sharks can sense electrical fields made by all living things, which helps them find hidden food. They also have a special system to feel movements and changes in the water around them.

Images

A large fossilized shark tooth showing its crown, shoulder, root, and root lobe.
Fossilized shark teeth from the Cretaceous period found in southern Israel.
A short-tail stingray swimming in its natural habitat.
A Japanese Port Jackson shark, showcasing this unique species of fish found in the ocean.
Illustration of a whale shark, one of the largest fish in the ocean.
Illustration of a lemon shark, a fascinating species of fish found in warm oceans.
Illustration of a great white shark, showcasing its distinctive features and anatomy.
An ancient hybodont fish, showing its unique features and appearance.
Illustration of an angel shark (Squatina squatina), a type of flat fish, by Henri Frédéric Paul Gervais.
Illustration of a sawshark (Pristiophorus nudipinnis), a unique species of shark known for its saw-like nose.
Illustration of a spiny dogfish, a small shark species found in the ocean.
A detailed close-up of tiger shark teeth, showcasing their unique serrated edges for learning about marine life anatomy.
Microscopic view of tiny tooth-like scales on a lemon shark's skin.
A hammerhead shark swimming in its natural habitat.

This article is a child-friendly adaptation of the Wikipedia article on Shark, available under CC BY-SA 4.0.

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