Other Minds: The Octopus, the Sea, and the Deep Origins of Consciousness

by Peter Godfrey-Smith

But this mechanism has no means to produce many other colors a cuttlefish might display. There’s no way to produce blue, green, violet, or silver-white. Those colors are produced by mechanisms in the next layers of skin. Here we find several kinds of reflecting cells. These cells do not display fixed pigments, as chromatophores do, but reflect back incoming light. This reflecting need not be a simple mirroring. In iridophores, light is bounced and filtered through tiny stacks of plates. These plates separate and direct the light’s different wavelengths, shining back colors that can be different from those that came in. The results include the greens and blues that chromatophores cannot produce. These cells are not attached directly to the brain, but it seems that some of them are controlled, more slowly, by other chemical signals.