A great hammerhead shark prowls the waters of the northern Bahamas. Photo by: Brian Skerry, National Geographic Stock.
A Shark’s-eye View Why are hammerhead sharks’ eyes so widely separated on their bizarrely shaped heads? Whatever the evolutionary reason for the placement, scientists have debated whether it was to provide good vision. Florida Atlantic University marine biologist Michelle McComb has settled that vision question by studying three of the eight types of hammerheads. She found that hammerheads see not only directly ahead with binocular vision similar to that of humans; they also see up, down, and behind themselves simultaneously. “Their eyes are canted forward, and that is the key,” McComb says. Their eye separation gives hammerheads great binocular vision and depth perception—a bonus when pursuing fast-moving prey.
Although hammerheads do have a particularly big blind spot in front of their widely spaced eyes, other senses compensate for this hole in their visual field. Sensors on the sharks’ heads help them detect electrical fields emitted by fish, and the placement of nostrils near their eyes could mean they use what McComb calls “enhanced stereo smell” to monitor the blind spot.
(Source: freshoptical.co.uk)
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