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
Dazzle camouflage the Animal Kingdom". Seeing the opportunity to put his theory into service, Thayer wrote to Churchill in February 1915, proposing to camouflage submarines by countershading them like fish such as mackerel, and advocating painting ships white to make them invisible. His ideas were considered by the Admiralty, but rejected along with Kerr's proposals as being "freak methods of painting ships ... of academic interest but not of practical advantage". The Admiralty noted that the required camouflage would vary depending on the light, the changing colours of sea and sky, the time of day, and the angle of the sun. Thayer