In this way, sick and dying fish and marine animals are removed from the population before they spread the disease. Weak individuals are culled from the breeding population. The law of survival of the fittest is enforced by sharks. Sharks have a unique and effective immune system. It forms nonspecific antibodies that attack disease immediately.
Humans have a specific immune system.
We have to be exposed to a disease before we can form the specific antibody to fight that disease. Sharks, unlike most animals, can heal a torn cornea. Shark corneas contain both rods and cones and could be used for transplant to humans. Sharks can also heal major wounds in short periods of time, often in 24 hours. Sharks have a resistance to cancer.