What Are Some Facts About Sharks?


Quick Answer

Sharks are fish, but unlike other fish, their skeletons are made of cartilage rather than bone, and instead of smooth, flat scales they have sharp, tooth-like scales called denticles. Scientists believe that sharks are 200 million years older than the oldest dinosaur, meaning they have been around for over 400 million years.

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Full Answer

Sharks have many unique characteristics that set them apart from other fish. Most fish only have one gill for breathing on either side of their body but sharks have multiple gills: five, six or even seven on each side. Sharks have extremely heightened senses that have adapted to make them incredible hunters. For instance, sharks have sensitive hearing and are able to hear things up to 700 feet away. They are known for their bites and have at least four rows of extremely sharp teeth. Sharks tear their food instead of chewing it. When a shark's front row of teeth wear out, the rows shift forward to replace it and new teeth form in the back row. Different species of sharks give birth to their babies or "pups" differently; some give live birth and some lay eggs. Regardless of how the pups enter the world, once a shark is birthed, it is on its own.

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