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I've read that unlike humans, octopuses have eyes "designed" the "right way", i.e. with the nerve fibers behind the retina, thus getting rid of the blind spot we humans have as well as theoretically improving eyesight.

Have there been tests to compare octopus sight with that of humans, and do they indeed have better vision than us?

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I'd suggest adding the tag "cephalopods". –  nbubis Jan 7 '13 at 12:20
    
Why would removing the blind spot result in better vision? –  terdon Jan 7 '13 at 12:30
    
the blind spot perhaps not, (although it could come in ahndy if the eyes are on the side of your head and not in front), but mostly one would think that the lack of nerve fibers would somehow improve resolution, vision in dim light, etc. –  nbubis Jan 7 '13 at 12:37
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up vote 7 down vote accepted

There are a couple of advantages and disadvantages of possessing the eyes of octopuses.

  • The first advantage of the octopus eye is that it has no blind spot. This means that octopuses can see everything that is going on in their environment, and are more aware of predators and prey than some vertebrates. Also, they have many more photoreceptors than vertebrates, at roughly 20,000-50,000/mm2 which means that their vision is much better than that of any human.

  • The disadvantage of the octopus eye is that it can not see in colour. The eyes possess no cones, only the invertebrate equivalent of rods. This means that octopuses can only distinguish between light and dark.

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So if a diver and an octopus where to be threatened by a shark, the octopus would see the shark first? –  nbubis Jan 7 '13 at 19:01
    
Of course it depends, As I cleared above both have some advantages and disadvantages. So, It's completely depends. But In some manner of course the Octopus will see the Shark first because they didn't have blind spot so their field of view is more than a common person. –  Alpha Jan 8 '13 at 5:38
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Nice answer, +1. Do you have a reference for the photoreceptor claim? –  terdon Jan 8 '13 at 17:19
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"Like other cephalopods, they can distinguish the polarization of light. Color vision appears to vary from species to species, being present in O. aegina but absent in O. vulgaris." - en.wikipedia.org/wiki/Octopus#Sensation –  MCM Jan 8 '13 at 18:58
    
Would the blind spot matter? The respective blind spots of the two eyes don't overlap, so unless you are a pirate (I suppose a frequent victim of sharks), you will still see all the things in either of your blind spots, there will just be two small spots in your FOV where you don't have depth perception. –  Superbest Apr 21 at 20:59
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