Cephalopods - Chameleons of the Sea
Cuttlefish, Octopus and Squid all have pigment cells - called chromatophores - consisting of yellow, red and brown pigments which allow them to change their appearance. There are up to 200 of these cells per square millimeter and each of them are controlled through muscle contractions - instead of hormones like other marine organisms - allowing them to consciously control them.
When signaling to change colors, the chromatophores can be rapidly expanded and then relaxed to hide the pigments and can even stay camouflaged while asleep. Chromatophores, however, only one type of cells. Other cells are layered below, made of white and iridescent pigments to reflect other wavelengths of light like blue and green.
Using all of these pigments, the cephalopods typically use 3 major pattern types; Uniform, Mottle (small light/dark splotches) and Disruptive. One of the coolest patterns is the Passing Cloud pattern which is used to hypnotize their prey. Among all of these amazing attributes, they can also change their skin texture voluntarily to match the object they are trying to hide next to and they do this through visual perception rather than touch.