A shark's tooth is about 5-16 cm, but the size of shark teeth varies greatly among different species. For example, Megalodon sharks with large teeth can have teeth length of about 10-16 cm in adulthood, and some larger teeth can reach more than 18 cm.

Sharks have special teeth. They have 3-6 rows of teeth in their mouths, but they only have the teeth in the front row, and the teeth in the back row are basically substitutes. After the teeth in the front row degenerate, the teeth in the back row will move to the front row immediately. This kind of habit and characteristic is very different from human beings, and it is very incredible to human beings. Sharks can change their teeth once a week or so, and a shark can change more than 30,000 teeth in its lifetime. Their tooth germ differentiation and calcification are very fast, so after their old teeth fall off, new teeth will be born quickly, which will not affect sharks' predation.

Sharks can have more than 6000 teeth in their whole mouth because their mouths are relatively large and they don't have only one row of teeth. An adult shark will have 3-6 rows of teeth in its mouth, so there will be more than 6,000 teeth in its whole mouth. Unlike humans, sharks can change their teeth many times in their lifetime. Some normal sharks will change more than 30,000 teeth in their lifetime, which is difficult for other creatures to achieve.