Cephalopod
Most cephalopods have chromatophores – that is, cells with different colours – which they can use in a number of surprising ways. As well as blending with their background, some cephalopods bioluminesce, shining light downwards to hide their shadows from any attackers. The bioluminescence is made by bacterial symbionts; the host cephalopod is able to find the light made by these animals. Bioluminescence may also be used to attract prey, and some species use colourful shows to get mates, amaze predators, or even signal to one another.