Sharks
Teeth
Teeth, one of the main components of the shark's natural predatory skills, are meant and shaped to pierce and destroy their prey (this is only for some of the larger species who eat larger prey). The range of the sizes of their teeth is incredible. Some can be as small as a pencil tip, but others, like the ancestor of the Great White shark, the Megalodon had teeth as big a as average man's arm. Some teeth are sharp saw-edged daggers like blades; while others are fine sharp cutting, smooth edges. Still, others may have a serrated section and the rest with a sword like edge. Many harmless species have small stubs for teeth, which they do not need for eating with. The most commonly found type of teeth is the fine cutting-edged razors, growing in a Thresher Shark's thin mouth. Sharks never stop growing teeth; an adult shark will go through 30,000 teeth in a lifetime. They have rows upon rows of teeth waiting to replace any worn out, teeth not in the best condition for their purpose. A shark can have up to about 1000 teeth in their mouth at a time. Eventually, old teeth just lose circulation of nutrients and just become weak, frail, useless stubs of decaying matter. The upper teeth in a sharks mouth tend to be larger than the lower teeth: this is because the upper jaw juts out more than the lower jaw and contact the fishes flesh first. In some species, the denticles by the upper and lower jaw, grow and eventually grow into teeth.
The size of a shark's teeth and the sharpness, affect a sharks behavior. The bigger and sharper the teeth are, the more likely they are to be aggressive and predatorily, and vice-versa. Because of their teeth, a shark is a shark.