When a shark's tooth falls out they grow a new one. They have an endless number of teeth. A shark will grow its tooth back if the tooth is broken or falls out. A shark could go through a thousand teeth in its life time A shark's jaw is loaded with teeth.
Sharks can have from five to seven gills.
This is the same substance that makes a cat s eye green. The six gilled shark needs this substance to see in dark, deep water. A dolphin will attack a shark to protect its young. Dolphins usually kill sharks. If you rub against a shark, you may bleed because their skin is like sharp teeth.