Animal Camouflage
Nature’s masters of disquise
Many animals can blend in with their surroundings. Called ‘camouflage’, colours and patterns, but often the animal’s behaviour is important too. Camouflage is used by predators to give them the element of surprise and also by prey in order to remain inconspicuous.
Blending in – From the polar bear moving unobtrusively over an ice floe to a green treefrog that is almost invsible against a rainforest leaf, many animals match the colour of their habitat. Some even blend in with their surroundingswhen seen from two different directions: from above the dark coloured back of the spotted eagle ray perfectly matches that of deep water, while its lighter underside blends in with the sky, when seen from below.
Break it up – In some cases , camouflage works by breaking up an animal’s outline, making it difficult to either distinguish it from its background, or to focus on individuals within a herd. The bold, black and white stripes of a zbra herd, for instance, confuse predators such as lions because the patterns disrupt the outlines of individual animals. To a lion, the herd appears as a single striped mass, particularly since the patterns are ‘out of line’ with the zebra’s shape.
Changing colour – some animals such as chameleons and cuttlefish can change colour rapidly, due to colour cells in the base of the skin called chromatophores. As the animal’s eyes record the coloursin its immediate environment, nerves send messages, aided by hormones, which react by causing the constriction of all the chromatophores of a particular colour. In this way the animal changes its hue to match its background. Some Arctic dwellers change fur colour with the season. The Arctic hare for instance is only white in winter. Changes in daylight or temperature produce hormonal changes that bring about a colour alteration to match the summer landscape.
Camouflage Extras – Some animals have extra body pats to make their disguises near-perfect. Few creatures better illustrate this than the leafy sea dragon, of Australian waters. This relative of the seahorse has flowing appendages that make the animal look like a piece of floating seaweed.
Great Pretenders – The animal’s behaviour is also vital to the succes of some disguises. Described as the ‘I’m not here bird’, the Central and South American potoo masquerades as a dead tree stump when danger threatens. With its lichen-coloured plumage, it perches still and upright, peering out through tiny slits in its eyelids. Using similar behavioural tactics, some leaf insects ensure that when resting on a twig, their leafy body points a similar way as nearby leaves, to blend in. The crocodile meanwhile sneaks up on prey by mimicking a semi-submerged log, floating along in the water.
Malayan Tapir’s Vanishing Trick – The Malayan Tapir’s half-black, half-white colouration may not look like camouflage but it is particularly effective. At dusk and dawn when the Tapir is active, these colours actually break up the animal’s outline in the jungle, making it hard for predators to see it.
[tags]colour, tapir, camouflage, trick[/tags]
