Hammerhead Sharks Could Have The Best Vision In Animal Kingdom

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It may be ugly but the distinctive snout of the hammerhead shark means it has some of the best “all round” vision in the animal kingdom, scientists have discovered. Researchers have found that the odd shape of the head allows the sharks, which can grow up to 20 ft long, to have a 360 degree field of vision in all directions.Not only does it have front, back and side vision it can also see vertically and judge depths, claims the study.

“We were very surprised, they really have remarkable vision,” said Dr Michelle McComb, lead author of the study at Florida Atlantic University”At any time when they are swimming they can not only see from side to side, in front and behind but also above and below.”The evolution of the odd shaped head has long puzzled scientists and many reasons such as manoeuvrability, smell and inbuilt “sonar” have been tested.

But this is the first time it has been proved that the odd shape improves their eyesight.The researchers used a machine called an “electroretinogram” to test the field of vision – firing a tiny beam of light at the shark in a darkened tank from all directions.

Electrodes embedded in the shark then picked up any signals sent from the eye to the brain.Comparing them with pointy nosed species, the team found that the scalloped hammerheads had the largest visual field for each eye. It so large at 182 degrees that both eyes together offer all round vision and even overlap at the front, creating an effect like binoculars.

Dr McComb said that the sharks not only have outstanding forward “stereo-vision” and depth perception, but a respectable stereo rear view too.She believes the reason may be the sharks position in the middle of the food chain: not only does it need excellent forward vision to find and kill prey but it also needs to watch its back against predators.

The paper was published in the journal of Experimental Biology.

(source)

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