Active camouflage the surface, so when marine animals are seen from below, they appear darker than the background. Some species of cephalopod, such as the eye-flash squid and the firefly squid, produce light in photophores on their undersides to match the background. Bioluminescence is common among marine animals, so counterillumination may be widespread, though light has other functions, including attracting prey and signalling. Color change permits camouflage against different backgrounds. Many cephalopods including octopuses, cuttlefish, and squids, and some terrestrial amphibians and reptiles including chameleons and anoles can rapidly change color and pattern, though the major reasons for this include signalling, not
Underwater camouflage predators and prey. Natural selection has produced a wide variety of methods of survival in the oceans. In Ancient Greece, Aristotle commented on the color-changing abilities, both for camouflage and for signalling, of cephalopods including the octopus, in his "Historia animalium": Three main camouflage methods predominate in the oceans: transparency, reflection, and counterillumination. Transparency and reflectivity are most important in the top 100 metres of the ocean; counterillumination is the main method from 100 metres down to 1000 metres; while camouflage becomes less important in the dark waters below 1000 metres. Most animals of the open sea use at least