Wednesday 10 February 2010 | Science = News feed=20
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'All seeing' hammerhead sharks could have the best vision in animal=20 kingdom
It may be ugly but the distinctive snout of the hammerhead shark = means it=20 has some of the best "all round" vision in the animal kingdom, = scientists have=20 discovered.
All seeing=20
hammerhead sharks Photo: AP =
Researchers have found that the odd shape of the head allows the = sharks,=20 which can grow up to 20 ft long, to have a 360 degree field of vision in = all=20 directions.
Not only does it have front, back and side vision it can also see = vertically=20 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,=20 in front and behind but also above and below."
The evolution of the odd shaped head has long puzzled scientists and = many=20 reasons such as manoeuvrability, smell and inbuilt "sonar" have been = tested.=20
But this is the first time it has been proved that the odd shape = improves=20 their eyesight.
The researchers used a machine called an "electroretinogram" to test = the=20 field of vision - firing a tiny beam of light at the shark in a darkened = tank=20 from all directions.
Electrodes embedded in the shark then picked up any signals sent from = the eye=20 to the brain.
Comparing them with pointy nosed species, the team found that the = scalloped=20 hammerheads had the largest visual field for each eye. It so large at = 182=20 degrees that both eyes together offer all round vision and even overlap = at the=20 front, creating an effect like binoculars.
Dr McComb said that the sharks not only have outstanding forward=20 "stereo-vision" and depth perception, but a respectable stereo rear view = too.=20
She believes the reason may be the sharks position in the middle of = the food=20 chain: not only does it need excellent forward vision to find and kill = prey but=20 it also needs to watch its back against predators.
The paper was published in the journal of Experimental Biology.
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