Squid eyesight??

Jan 25, 2003
Hi folks:smile:)

I am wondering if squid, octos and cuttle fish have full colour vision??

I was wondering if a deep sea squid would actually need colour vision as thier environment is so dark naturally, so my presumption would be that they only need light sensors rather that a larger spectrum.

Or do they in fact have eyesight that progresses into the "invisible" lights that we cannot see?? i.e. ultraviolet, infra red or whatever else is down there.

Has there been any studies on the availability of these other forms of light down in thoise depths??

Have fun, keep smiling and take care.

Colour Blind

Cephalopods have only one visual pigemtn, meaning that most cephalopods are colour blind. However, "octopuses can discriminate cetween two shapes on the basis of 1) brightness, 2) size, 3) horizontal/vertical orientation, 4) form, and 5) plane of polarization."
All of this information was foundin Cephalopos Behaviiour by Hanlon and Messenger p. 18-19.

Michael O'Shea
Very interesting Michael,
It surprises me that they are in fact colourblind when you see them change colour to mimic exactly surrounding colours.

Plus sometimes they have a definite preference for a particular colour eg red, pink, orange and light purple i would think would look almost identical in black and white, yet they will attack maybe the orange colour but refuse to entertain any other colour. The jigs im talking about are all identical size shape and model, just in differing colours.

Keep smiling and take care,
I believe that the differentiation may be due to relative brightnesses between the different colors. I don't remember which book it was, but they mentioned that octopuses could not distinguish between different colored objects that were matched for brightness. However, I believe there is at least one squid species that has multiple visual pigments (Histioteuthis? I don't have any of my books at work with me), and it is presumed that this particular animal may be able to distinguish colors. However, I am no scientist, merely an interested layperson, and it is up to the real scientists here to give you a definite answer!
Oop, I was quite wrong. In flipping thru Cephalopod Behaviour last night, I noticed that it was in fact Watasenia scintillans that is credited with having three visual pigments. Anybody have any more information on these animals? Do we know whether they have color vision yet?

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