Shark meat is poisonous to people. All sharks have to swim constantly. Sharks have poor vision. Sharks are hard to kill. A shark is a shark is a shark.
Sharks are trash fish.
The biggest enemy to sharks is man. Sharks are a critical part of marine ecosystems, a source for knowledge to help the human condition, and the basis of a valuable fishery. Sharks' eyes, which are equipped to distinguish colors, employ a lens up to seven times as powerful as a human's, and some shark species can detect a light that is as much as ten times dimmer than the dimmest light the average person can see. Some sharks can respire by pumping water over their gills through opening and closing their mouths while at rest on the bottom. Great whites are relatively uncommon large predators that prefer cooler waters.