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

by Peter Godfrey-Smith

This is baffling. These animals are doing so much with color. They are also superb at matching the color of their surroundings, for camouflage. How can you match colors you cannot see? Biologists sometimes offer explanations along these lines: First, cephalopods may be using subtle differences in brightness as indicators of the likely colors (hues) of objects around them, given the typical colors in their environment. Second, the reflecting cells, the mirrors in the skin, can help. You can produce a color you cannot see by reflecting it back from outside. This makes sense of some of what cephalopods can do. Camouflage can be achieved with reflection—if the color you aim to match in your background is also coming toward you from other directions. Simple reflection cannot be the explanation if an animal is matching a color behind its back, while the light coming in from the front is different.