Sharks do not attack humans purposefully. They evolved millions of years before humans have existed and therefore humans are not part of their food menu.
Although sharks are known for their violent attacks, it has to be noted that sharks are not evil creatures constantly looking for humans to attack. There are more than 440 species of sharks in the world. Among those only a dozen have been involved in attacks on humans. More specifically Great white, tiger and bull sharks.
Sharks are predators sitting at the top of the ocean's food chain. They are designed to hunt and eat a lot of meat to survive. They consume mainly other sea creatures like small fishes, sea lions, sea otters, sea turtles, whales and seals. So why the attack happens?
Sharks are highly concentrated in Eastern cape of South Africa, Hawaii, Australia, Brazil where human population is also high on waters.
"If these animals are chasing bait fish, the flash of a roughly oval shape surf board with arms and legs dangling off, paddling along bears them a close resemblance to a sea lion or a sea turtle ".
The sharks are simply mistaking a human for something it usually eats. Once the shark gets a taste, it realizes that this is not its usual food, and it lets go. When a large animal like a tiger shark or a white shark, which move quickly, bites, it is far more likely to be fatal.
The accidental attacks happen when they try to investigate its prey. Sharks are animals obeying their instincts, like all other animals. In fact, Sharks have more to fear from humans than we do of them. Humans hunt sharks for their meat, skin, internal organs and fins to make products like leather, lubricants and shark fin soup.
Sharks are a valuable part of marine ecosystem. Instead for giving them a scary reputation, attacks can be avoided in some ways.
Do not swim in water that is not clear.
Do not wear shining jewelry or bright clothes.
Do not swim at dawn or dusk. (poor visibility and these are shark's active feeding times).
Swim in groups.
Avoid excess splashing, as sharks are drawn to the noise.
Do not swim where the shark's prey is present in large numbers like sand bars, sea mouths or drop offs.
Most importantly, do not swim when you know there are sharks in the water.