Can octopuses see through their eye lids?

CaptFish

Colossal Squid
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#1
I have noticed with two of my octopuses Leggs, O.briareus, and Pen, unknown species, Both perch on top of the live rock and appear to be sleeping. You can clearly see that their eyes are closed; however, if I make a sudden movement or approach the tank it is clear they can see me. I just watched Pen do it two seconds ago. He was sitting just outside his den with his eyes closed and I leaned back in my chair and stretched which caused him to quickly change camouflage and he opened his eyes. He briefly responded to my movements and now he appears to be sleeping again.

So can they see through their eye lids? Or are their eyes not really closed?
 

DWhatley

Cthulhu
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#2
Another member asked if their skin/arms might have light sensativity (similar thought where lighting changed and caused a reaction but the eyes did not appear to be involved) but the question was never really resolved.
 

CaptFish

Colossal Squid
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#3
It's clear that both octopuses could detect me with there eyes closed. All I have to do is wave my arm in front of the tank and sure enough the eyes open. I remember the post your talking about, it ended with a post about how Roger Hanlon is studying that now.
 

cuttlegirl

Colossal Squid
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#4

Jean

Colossal Squid
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#5
In my understanding octopus don't actually have eyelids! BUT they can narrow down both the pupil and the actual eye diameter (at least that's how it looks in ours!!!)
 

Level_Head

Vampyroteuthis
Registered
#6
Jean;162775 said:
In my understanding octopus don't actually have eyelids! BUT they can narrow down both the pupil and the actual eye diameter (at least that's how it looks in ours!!!)
It appears that at least some species can partially retract their eyes or close the aperture around the eye, and many papers speak matter-of-factly about eyelids. In the paper "Circadian rhythms to light-dark cycles in the lesser octopus, Eledone clrrhosa" it says:
In this condition the eyelids remained closed and the octopus, pale in colour, was unreactive to disturbance.
In another paper, Development Influences Evolution:
Many biologists point to the development of human and octopus eyes as an example of convergent evolution. Both eyes have an eyelid, iris, lens, pupil and retina, but they are formed by completely different mechanisms.
This paper, Convergent Evolution of Camera Eye (full PDF document), has a diagram of analogous structures of human and octopus eye (see graphic on page 1556) showing the eyelid on each:
Structural similarities between human and octopus eyes. Even though there are some differences between human and octopus eyes, each of the tissues such as eyelid, cornea, pupil, iris, ciliary muscle, lens, retina, and optic nerve/ganglion corresponds well to each other.
An aquatic creature would not have the frequent blinking that terrestrial mammals do to keep the cornea moist; it would primarily be for protection. And indeed, it is rarely evident in octopus photos and videos that I've seen.

An aside: In my novel, I've written that octans—evolved, roughly human-intelligent octopuses—rarely blink per se. What we would consider a "wink" they do with a twitching of an eyestalk. Nevertheless, they can blink and their word for "blink" has entered their language as a very short period of time. (Technically, about a third of a second; their time is based on 64 periods in a day, then two more layers of 64 below that.)
 

Jean

Colossal Squid
Supporter
#7
Thanks for the info. Ours I'd say is more of the retract type there are definitely no eyelids (I went and looked!).

Sorry to say haven't had much time to read your novel, but what I have read so far I'm thoroughly enjoying!
 

DWhatley

Cthulhu
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#8
Jean, if you get a chance with your new camera can you try to get a close-up? All the ones I have kept have something I would call an upper and lower lid that can change color and open and close.
 

skywindsurfer

Architeuthis
Registered
#9
From what I've experienced with E. Dofleini there doesn't seem to be an eye lid, but they appear to have the ability to 'squeeze' the skin around their eyes in a circular fashion to sort of close their eyes. From what I know about eye lids, they are generally one solid mass that goes from one side to the other. I've noticed this with O. Hummelincki and O. Briareus a little but not so much as E. Dofleini.

Though as I've never diesected an octopus before I can't say yes or no for certain.
 

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