Hiding In Plain Sight
Many animals use camouflage to hide or to disguise themselves. People can use it also; the idea is simply to not be seen. Photo of katydid courtesy of James Mallet
Camouflage can have different purposes. Most often we think of animals using it to avoid being seen by predators, but predators also use camouflage to hide from prey to allow them to either sneak up on their intended victims or to lie in wait unseen so they can suddenly attack.
Generally animals will blend in with their usual backgrounds. A lion is a tawny color to avoid being seen as it sneaks through the dry grass towards its prey. The coats of mice vary even within a species depending on where they live so that they will be less visible to predators. Moths have been found to change color over relatively few generations in response to environmental conditions. For instance, the peppered moth was originally light colored, but as a result of the Industrial Revolution in England the trees it rested on became covered with soot, so darker forms were more likely to survive and became dominant. WIth the recent reduction in pollutants and soot, the tree trunks are returning to their natural states and the moths are once again becoming lighter in color - a classic case of natural selection.
Baby animals whose mothers park them under trees during the day often have dappled or striped coats to help them blend in - lion cubs, fawns and baby tapirs for instance - but lose their spots as they grow. Jungle or tree dwellers, whether predator or prey, may have spotted or striped coats for the same reason - tigers, leopards, jaguars,
Still others may have patterned coats that don't really camouflage them but might help confuse would-be predators. It was long thought that the stripes of zebras had this function; but since the stripes also vary from animal to animal they are probably also used for identification. Now recent research suggests that some biting flies avoid landing on black and white stripes; see "The function of zebra stripes" by Caro et al. in Nature Communications 5 ( 2014).
Photo by D. Barr
Some animals have spectacular ways of using camouflage. The chameleon changes color to blend in with its background of the moment. Octopuses, cuttlefish and squid use chromatophores to change their appearance, often instantly and dramatically.
Photo by RIchard Ling
There are other kinds of camouflage too. Some butterflies, insects and even birds are very flashy when in motion, but when they stop and settle they become cryptic, blending in with their surroundings so as to practically disappear. An excellent example is the male blue morpho butterfly; its underwings are drab brown so when it is settled or feeding with its wings closed it is very hard to see. When it takes flight, however, there are flashes of bright blue from the tops of the wings, adding another layer of protection by startling would-be predators. This is also an example of camouflage - with a flip side.
Top view of blue morpho male followed by bottom side.
(Incidentally, female morphos look like the undersides of the males on both sides.)