Why do sharks have so many teeth?

Sharks make stacks of extra teeth because hunting breaks and loosens them all the time. Their teeth grab, slice, and tear rather than chew, and many sit in soft gum tissue instead of deep sockets. When one drops out, a waiting tooth can move into place quickly.

The jaw works like a living supply shelf: rows behind the front edge keep developing throughout life. Great whites carry broad cutting teeth, tiger sharks have shell-cracking blades, and quieter bottom feeders use flatter ones for crabs and clams. A beach tooth may be one old tool from a very busy mouth.