The hammerhead shark is an underwater mystery. Why is its head shaped like a hammer? Nobody is sure. For years, people thought the shark's shape helped it to smell food, or swim faster. But now there is a new idea about this strange animal.
It seems that the hammerhead can see better than other sharks. Although its eyes are far apart, it can look up, down, left, and right. It can also see straight ahead. It can easily guess the distance between itself and other fish. This means that the hammerhead shark can hunt very well.
This shark changed the shape of its face over thousands of years. As its face got bigger, it saw more and more of the sea around it. It could catch more fish to eat. The hammerhead changed because it needed to survive.