Hammerhead sharks - Evolutionary process

For over a century, scientists have speculated why hammerheads evolved such an odd shape and whether having eyes so far apart would enhance their vision.

In 1942 a leading authority on sharks, Gordon Walls, suggested the position of the shark's eyes prevented it from having binocular vision but others have argued exactly the opposite, saying the animals must have enhanced eyesight.

Now, hammerhead sharks have had their first eye examination, and it has laid the debate to rest. Sharks with wider heads have better binocular vision – all the better to track fast-moving prey like squid with far more accuracy than sharks with close-set eyes.

The research also shows that hammerheads – among other sharks – have a 360-degree view of the world in the vertical plane, allowing them to simultaneously see prey above and below them.