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 was heading and where to aim. However, the ships painted in dazzle were larger than the uncamouflaged ships, 38% of them being over 5000 tons compared to only 13% of uncamouflaged ships, making comparisons unreliable. With hindsight, too many factors (choice of colour scheme; size and speed of ships; tactics used) had been varied for it to be possible to determine which factors were significant or which schemes worked best. Thayer did carry out an experiment on dazzle camouflage, but it failed to show any reliable advantage over plain paintwork. The American data were analysed by Harold Van Buskirk in