Loligo can change from a bright red to a greenish hue to almost transparent in the blink of an eye. Other cephalopods have even more impressive displays with moving patterns and shifting iridescence. They have such control over these colors and patterns that they use them to communicate with each other as well as warn other species. This ability to control color is another example of the finely tuned nervous system of cephalopods. The skin itself is nearly transparent.
Color comes from cells full of pigment known as chromatophores .
These cells are like flexible bags of paint. They are controlled by muscles which are in turn are controlled by nerve fibers connected to the brain. When the muscles contract, the chromatophore is spread apart and the result is a spot of color. When the muscles relax the chromatphore returns to a compact shape and the color shrinks to a small dot. A nerve fiber might control several chromatophores.