Camouflage there is no background, the principal methods of camouflage are transparency, silvering, and countershading, while the ability to produce light is among other things used for counter-illumination on the undersides of cephalopods such as squid. Some animals, such as chameleons and octopuses, are capable of actively changing their skin pattern and colours, whether for camouflage or for signalling. It is possible that some plants use camouflage to evade being eaten by herbivores. Military camouflage was spurred by the increasing range and accuracy of firearms in the 19th century. In particular the replacement of the inaccurate musket with the rifle made
Snow camouflage to escape the conclusion that cryptic brown summer plumage becomes a liability in snow, and white plumage is therefore another cryptic adaptation." All the same, he notes, "in spite of winter plumage, many Ptarmigan in NE Iceland are killed by Gyrfalcons throughout the winter." Some animals of the far north, like the showshoe and Arctic hares, Arctic fox, stoat, and rock ptarmigan change their coat colour (by moulting and growing new fur or feathers) from brown or grey summer camouflage to white in the winter; the Arctic fox is the only species in the dog family to do so. However,