Thirty species are considered dangerous. Even so, more people die each year from bee stings than from shark bites. The largest sharks, the whale shark and the basking shark, don't have teeth for chewing. An adult whale shark has over four thousand tiny little teeth, less than one-tenth of an inch long. Like some whales, they filter tiny shrimplike plankton from the water into their bite-less mouths.
Some sharks are so well equipped for eating that they're all teeth.
Shark skin, which feels like sandpaper, is actually many small teeth linked together. They are the shark's version of the scales that cover other fish. Inside their skin, sharks are different from most fish, too, because their skeleton is made up of cartilage, which is softer and more flexible than bone. Some sharks have five rows of teeth. When one tooth breaks, another tooth which was lying down right behind the broken one, pops up, ready to work.