>What do they see?  And who are they? We know that some mollusks have
>"eyes". Is this "seeing" a family matter? Does depth, amount of light,
>affect seeing? Of those mollusks that do "see", what kind of world do
>they envision?
>     Q'Man

Hi Art

I'm sure this varies from species to species. I doubt that you can
even tell by presence or absence of a lens... pinhole (lensless)
cameras can cast quite a decent image.

Active beasts with elaborate eyes, such as stromboids, I'm sure have
acute sight. AND color vision. Trochids? Possibly rather poorer
vision, but no doubt still in color (I doubt any "normal"molluscs
will have grayscale vision, unlike most "higher" mammals. Carinaria
and other highly-active holoplanktonic heteropod predators must have
acute sight.

Polyplacophorans and pectinoids? Who knows? Possibly no better than
sophisticated light-sensors (possibly grayscale here).

Of course light levels are important, and some deepish-dwelling
species have good eyes... perhaps these can pick up the very limited
light (violet end of spectrum) reaching upper-bathyal depths (say
300m or a bit more)?
--
Andrew Grebneff
165 Evans St, Dunedin 9001, New Zealand
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