Sharks have a variety of different shaped teeth designed for their specific prey. Sharks that eat fish typically have narrow-shaped teeth. Sharks that feed on bivalves or crustaceans have plate-shaped teeth. The largest of the sharks, whale and basking sharks, have tiny teeth but do not use them at all as they feed primarily on plankton. While sharks that feed on mammals and turtles have large, serrated teeth. Some sharks will go through 30,000 teeth in their lifetime!