Sunday, 27 November 2016

zoology - Do octopuses have better eyes than humans?


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?



Answer




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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