Posts tagged with vision

Written by Veronique Greenwood

An unknown number of women may perceive millions of colors invisible to the rest of us. One British scientist is trying to track them down and understand their extraordinary power of sight.

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These special arthropods (stomatopods) have 16 visual pigments! We only have four, and we can see millions of colors. Their vision is hyperspectral, they can see ultraviolet and infrared wavelengths, as well as polarized light.  They have 360 degree vision and three parts of each eye can focus on the same spot, so each individual eye has trinocular vision with depth perception.  They have a very large focal range and the eyes can emit light, which is used for communication.
They have the most complex visual organs on the planet.

Mantis shrimp. There are 400 different species divided into two distinct groups: spearers and smashers.

These special arthropods (stomatopods) have 16 visual pigments! We only have four, and we can see millions of colors. Their vision is hyperspectral, they can see ultraviolet and infrared wavelengths, as well as polarized light.  They have 360 degree vision and three parts of each eye can focus on the same spot, so each individual eye has trinocular vision with depth perception.  They have a very large focal range and the eyes can emit light, which is used for communication.

They have the most complex visual organs on the planet.

Mantis shrimp. There are 400 different species divided into two distinct groups: spearers and smashers.

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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.” - Jim Dawson (Nat. Geo.)

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.”

- Jim Dawson (Nat. Geo.)