How do sharks replace so many teeth?

Only the teeth at or near the jaw margin do most of the feeding work. Behind them sit successive generations at different stages of development. As tissue supporting the tooth file moves, a replacement rotates or advances into position. Unlike mammal teeth, shark teeth are not rooted deeply in bony sockets, so shedding a damaged tooth is relatively easy.

Developmental studies describe a conveyor-belt-like process controlled by the dental lamina. Stem and progenitor cells help initiate new teeth at the inner side of the jaw, where they mineralize before joining the functional series. This active tissue is why continuous replacement can persist through an animal’s life instead of ending after two sets.

Popular claims often give a single replacement interval for all sharks. In reality, turnover can range from days to weeks and changes with species, tooth position, age, temperature and feeding. A nurse shark crushing hard prey and a white shark slicing flesh use different tooth shapes and loading patterns, so their replacement systems should not be treated as identical clocks.

Cartilage rarely fossilizes as completely as bone, while mineralized teeth preserve well. Constant shedding therefore gives scientists and beachcombers an enormous archive. Tooth shape can reveal feeding style and taxonomic relationships, but identifying a species from one worn tooth still requires care because shape changes across the jaw and through growth.