Sharks are not found in freshwater. Most sharks cruise at high speed when they swim. Sharks have peanut-sized brains and are incapable of learning. 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.