Shark's teeth are mostly triangular, the root is very short, and the crown is much longer than the root. Shark's teeth are not directly fixed on the mandible, but embedded in the gums. This structure makes the shark's teeth fall off easily when biting food. Sharks have terminal teeth, no relatively complete root and no alveolar fossa, so they are easy to fall off. Sharks can have multiple pairs of teeth, arranged from front to back. When the teeth on the edge of the front jaw wear or fall off, the back teeth move forward to replace the old teeth. During the shark's life, these teeth are always renewed.

Shark's teeth are only attached to soft tissues without strong support, so sharks can't chew food like humans, so they can only tear it open and swallow it directly. From this point of view, the function of shark teeth is similar to that of human fangs and incisors. Because shark's teeth fall off easily, sharks usually have 5-6 rows of teeth at the same time. Except for the outermost row of teeth, the other rows are "supine" standby, just like tiles on the roof, covering each other.

Once the outermost teeth fall off, the teeth in the inner row will move forward immediately to make up for the vacant position to replace the fallen teeth. Most species replace one tooth at a time, and only the Brazilian Dharma shark can replace an entire row of teeth at a time. Shark's teeth will be constantly updated and replaced throughout his life. The replacement teeth first grow in the grooves of the upper and lower jaws, and then move forward slowly like a conveyor belt.

The frequency of replacement may range from about 10 days to several months. At the same time, the larger teeth of sharks will constantly replace the smaller teeth during their growth. So sharks often have to change tens of thousands of teeth in their lifetime. According to statistics, should 10 change a shark? More than 20 thousand teeth.