In a cloaking clip from the PBS documentary Octopus: Making Contact, a sleeping octopus began changing colors as she seemingly dreamed as she lay upside down in the water. As this was happening, marine biologist Dr. David Scheel amusingly narrated what the dream might be in accordance with the particular shade of camouflage being exhibited at each moment.
From video narration: "So here she’s asleep, she sees a crab and her color starts to change a little bit. Then she turns all dark. Octopuses will do that when they leave the bottom. This is a camouflage, like she’s just subdued a crab and now she’s going to sit there and eat it and she doesn’t want anyone to notice her. …This really is fascinating. But yeah, if she’s dreaming that’s the dream."
Cephalopods are the ultimate color-changers, able to match their backgrounds in an instant so perfectly that even a keen observer can lose them. As invisibility cloaks go, theirs are close to perfect. Cephalopod skin is like a pixelated video screen. The top layer contains tens of thousands of tiny pockets of three different colors that can be opened and closed at will to display bright reds, yellows, browns or other shades, depending on the palette a particular species has. Below them lies a layer of reflective cells that interacts with stacked plates to create iridescence. Underneath them is another reflective layer to bounce back incoming light.
Cephalopod skin patterns are no mere color-matching trick. They are capable of scintillating moving displays, flashing pulses of color like passing clouds, forking silver lighting or shimmering waves from a stone thrown into a pool. Cuttlefish can play two screens at once on their bodies, sending signals to entice a possible mate from one side and warning off competitors with a separate display on the other.