Sharks have extremely well-developed sensory capabilities . Their eyesight is good, but depends greatly on water clarity. As sharks approach their prey, they can detect the faint electrical fields give off by all living organisms. Receptors on their snouts, known as ampullae of Lorenzini , allow sharks to locate their prey without seeing it. Using these senses, sharks can find prey at dusk, night and dawn, which is when inshore species are generally believed to feed.
Sharks are very well aware of their environment and appear to be fairly curious by nature.
They are aware of people in the water before people are aware of them. Encounters between sharks and people are infrequent, and most inshore species pose little threat to humans. While any shark may be potentially dangerous , only a few species of Hawaiian sharks are known to attack people. They include the Tiger , Galapagos , Gray Reef and Scalloped Hammerhead . The latter two appear to attack only when provoked.