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. If our sense of smell were as good as a shark's, we could tell what our friends across town were having for dinner. Sharks can smell some substances that are as diluted as one part odor to one billion parts of sea water. Sharks are also very, very sensitive to electrical fields. Every living body gives off a small electrical field around its body.