Sharks are efficient predators, with a highly developed sense of smell, hearing and sight. They can scent their prey in the water from great distances, and their sensitive eyes can see clearly even in the dim light of the deep ocean.
Sharks are carnivorous and eat invertebrates and fish, including other sharks. Large species may eat seals, turtles and penguins. Sharks are the top predators in many marine ecosystems, although some sharks, like the whale shark and the basking shark feed on plankton.
To date, scientists have identified more than 1,000 shark and related species. More than 400 species are shark. Only a few of these species have records that they attacked on humans. Yet sharks continue to hold a negative reputation as a danger to people.