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.