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Science!: Hammerheads, Fly Sex and Evolution

Lauren Admire | 30 Nov 2009 21:00
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Hammerheads Have Great Views

So, besides looking really badass, what is the reason for the strange layout of the hammerhead shark's head? The general consensus has been that the sharks could not have binocular vision because their eyes are stuck on either side of their head, but that they probably have excellent depth perception. It's been widely claimed that they have the best eyesight of any other shark, but this theory had not actually been tested, until now.

A team led by Stephen Kajiura and Timothy Tricas tested hammerhead sharks to see how wide their field of view was and if they had binocular vision. They collected specimens with heads ranging from narrow to wide, and swept a light in horizontal and vertical arcs around each of their eyes. They recorded each eye's electrical activity, which would show if the shark's eyes were reacting to the light. They found that scalloped hammerheads had the largest visual field, followed by the bonnethead, blacknose and lemon sharks. Next, they plotted the visual fields of both eyes on a chart to see if they overlapped, which would indicate that the sharks possessed binocular vision. Amazingly, they did overlap, proving that, despite how far apart their eyes are, they are still used together. Even more impressive, because of their stereo rear view, hammerhead sharks have a nearly 360 degree view of the ocean world.

However, because of how far apart their eyes are, hammerhead sharks do have a blind spot - directly in front of their heads. So, if you see one coming at you, try to maneuver yourself appropriately to not be spotted. That, or have a tank of gas and rifle handy.

Source: Science Daily

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