CAMOUFLAGE IS THE by-product of an evolutionary arms race between one group—the predators—that want to eat another group—the prey. Prey seek to survive by tricking the perceptual and cognitive systems of the predators. And predators look to eat by breaking through the camouflage of the prey.
To put it all more formally, predators need to maximise their perception of signal (their proposed meal) from the noise (the general environment); the goal of prey is to minimise that same signal-to-noise ratio. While the physical manifestations of camouflage might be diverse, they function in one of three ways: to impair detection, to impair identification or to redirect attack. Methods that impair detection trick the perceptual system of a predator into believing that the prey is simply not there. Octopuses change colour to match their backgrounds, for example. The tasselled wobbegong shark (pictured) conceals its shadow against the ocean floor by being incredibly wide and flat. The white bellies of penguins match the sky, and their black coats, the depths of the ocean, in what is known as “countershading”. The arctic fox sports white fur in the winter and brown or grey in the summer. The comb jelly is transparent. Deep-sea fish are very black.