Camouflage

This article is about protective coloration. For other uses, see Camouflage (disambiguation).

A disruptively patterned Flounder blending in with gravel on sea floor

Camouflage is a method of concealment that allows an otherwise visible animal, military vehicle, or other object to remain unnoticed by blending with its environment. Examples include a leopard's spotted coat, the battledress of a modern soldier and a leaf-mimic butterfly. Camouflage is a form of visual deception; the term probably comes from camouflet, a French term meaning smoke blown in someone's face as a practical joke. Military camouflage is part of a broad area of deception and concealment from all means of detection including sound and radar, and involving non-camouflage techniques such as use of decoys and electronic jamming.

According to Charles Darwin's theory of Natural Selection, characteristics such as camouflage that help an animal to survive will tend to evolve in any population.

Camouflage, whether in animals or in military use, can be achieved in different ways, including the apparent opposites Mimesis—being seen, but resembling something else, and Crypsis—being hidden. In both cases, however, camouflage is achieved not by actual invisibility, but by not being noticed. A third approach, Dazzle, found military application in the 20th century.

Camouflage is not the only form of Animal coloration that helps animals to survive. Other adaptations include Warning coloration, non-concealing forms of Mimicry (as when a harmless Hoverfly resembles a stinging Wasp), the use of bright colours in Sexual selection, and the use of pigment in the skin to protect against sunburn.

Camouflage by mimesis

Further information: Mimicry

In Mimesis (also called Masquerade), the whole animal (or piece of military equipment) looks like some other object, which is of no special interest to the observing animal or enemy. Mimesis is common in prey animals, for example when a Peppered Moth caterpillar mimics a twig, or a grasshopper mimics a dry leaf.

Mimesis is also employed by some predators (or parasites) to lure their prey, for example, a flower mantis mimics a particular kind of flower, such as an orchid

A different, non-camouflage strategy is Mimicry, where an animal boldly resembles another animal, typically one that is poisonous or distasteful: it is then easily seen, but avoided.

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  Peppered Moth caterpillars are superb twig mimics on birch (left) and willow (right) branches

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  Flower Mantis lures its insect prey by mimicking a Phalaenopsis orchid blossom

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  Hooded Grasshopper Teratodus monticollis, superbly mimics a leaf with a bright orange border

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  This Grasshopper hides from predators by mimicking a dry leaf

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  WWII Battle Tank hides from the enemy by mimicking a truck

Camouflage by crypsis

See also: Crypsis

Crypsis means blending with the background, making the animal (or military equipment) hard to see (or to detect in other ways, such as by sound or scent: for details, see Crypsis). Camouflage - visual crypsis - can be achieved in many different ways, including:

• General resemblance to background
• Disruptive patterning (breaking up outline)
• Eliminating shadow
• Crypsis by behavior
• Crypsis by changing skin pattern, color
• Countershading
• Counterillumination

These ways of achieving crypsis are described below.

General resemblance to background

Some animals' colors and patterns resemble a particular natural background, for example the Peppered Moth adult blends in with tree bark.

Disruptive patterning

Some animals, whether predators or prey, have disruptive patterns that help to achieve crypsis by breaking up their outlines with strongly-contrasting markings, for example in the Leopard. Disruptive patterns "are characterized by high-contrast light and dark patches, in a nonrepetitive configuration, that also provide camouflage by disrupting the recognizable shape or orientation of the animal".

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  Leopard: a disruptively camouflaged (and countershaded) predator

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  The Egyptian Nightjar nests in open sand with only its disruptive plumage to protect it

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  Papuan Frogmouth Podargus papuensis, superbly disruptive

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  Jumping Spider: a disruptively camouflaged invertebrate predator

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  A soldier applying a disruptive pattern to his face; his helmet and jacket are both disruptively patterned

Further information: List of camouflage patterns, Disruptive pattern material, and Military camouflage

Disruptive patterning is now common in military usage, both for uniforms and for military vehicles. Disruptive patterning, however, does not always achieve crypsis on its own, as an animal or a military target may be given away by other factors including shape, shine, and shadow.

Eliminating shadow

Some animals, such as the Horned Lizards of North America, have evolved elaborate measures to eliminate shadow: their bodies are flattened, with the sides thinning to an edge; the animals habitually press their bodies to the ground; and their sides are fringed with white scales which "break up and camouflage any dark shadow line that might fall along the body's edge." The theory that the body shape of the Horned Lizards which live in open desert is adapted to minimize shadow is supported by the one species which lacks fringe scales, "perhaps the exception that proves the rule": the Roundtail Horned Lizard, which lives in rocky areas and resembles a rock. "When threatened, it enhances this resemblance by hunching up its back, an act that displays rather than hides its three-dimensionality."

"Elimination of shadow" was identified as a principle of military camouflage during the Second World War.

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  Three countershaded and cryptically coloured Ibex almost invisible in the Israeli desert

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  "Shape, shine, shadow" make these 'camouflaged' military vehicles easily visible

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  The Flat-tail Horned Lizard's body is flattened and fringed to minimise its shadow

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  Camouflage netting is draped away from a military vehicle to reduce its shadow

Crypsis by behaviour

Decoration, keeping still, lying flat

Some animals actively seek to make themselves cryptic by using materials from their environment, such as twigs, sand, or pieces of shell to conceal their outlines, for example when a Caddis Fly larva builds a decorated case, or when a Decorator Crab covers its back with seaweed, sponges and stones. Most other forms of crypsis also require some animal behaviour, e.g., keeping still, lying flat, as in the Flat-tail Horned Lizard, or swaying as if rippled by wind or water currents, as in the Leafy Sea Dragon.

Similar principles can be applied for military purposes, for example when a Sniper wears a Ghillie suit designed to be further camouflaged by decoration with materials such as tufts of grass from the sniper's immediate environment.

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  Sniper camouflaged with a Ghillie suit and plant materials from the environment

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  Crab camouflaged with algae from the environment

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  Leafy Sea Dragon camouflaged by pattern, shape, colour and swaying like the seaweed that it mimics

Motion camouflage

Most forms of camouflage break down when the camouflaged animal or object moves, because the motion is easily seen by the observing predator, prey or enemy. However, some insects such as hoverflies and dragonflies use Motion camouflage, the hoverflies to approach possible mates, and the dragonflies to approach rivals when defending territories. Motion camouflage is achieved by moving so as to stay on a straight line between the target and a fixed point in the landscape; the pursuer thus appears not to move, but only to loom larger in the target's field of vision. Numerical simulations show that motion camouflage can be more efficient than classical pursuit (moving straight towards the target at all times). The same technique could be used for military purposes, for example by missiles to minimise their risk of detection by the enemy.

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  Male Syritta pipiens hoverflies use motion camouflage to approach females

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  Male Australian Emperor dragonflies use motion camouflage to approach rivals

Crypsis by changing skin pattern, colour

Further information: Animal coloration and Category:Animals that can change color

Animals such as chameleon, flatfish, squid or octopus actively and rapidly change their skin patterns and colours using special chromatophore cells to resemble whatever background they are currently resting on (as well as for signalling).

On a longer timescale, some animals like the Arctic hare, Arctic fox, Stoat (also called Ermine), and Ptarmigan change their coat colour (by moulting and growing new fur or feathers) from brown or grey in the summer to white in the winter; the Arctic fox is the only species in the dog family (Canidae) to do so. However, Arctic hares which live in the far north of Canada, where summer is very short, remain white all year round.

Again, similar principles can be applied for military purposes. Active camouflage could in theory make use of both dynamic colour change and counterillumination. Simpler techniques such as changing uniforms and repainting vehicles for winter have been in use since the Second World War.

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  Rock Ptarmigan, changing colour in springtime. The male is still mostly in winter plumage

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  Soldiers change uniforms to snow camouflage in winter

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  Arctic Hares in the Low arctic change from brown to white in winter

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  Snow-camouflaged German vehicles in Russia, October 1941

Crypsis by countershading

Main article: Countershading

Countershading uses graded colour to create the illusion of flatness. Shadow makes an animal lightest on top, darkest below; countershading 'paints in' tones which are darkest on top, lightest below, making the countershaded animal nearly invisible against a matching background. American artist Abbott Handerson Thayer's observation that "Animals are painted by Nature, darkest on those parts which tend to be most lighted by the sky's light, and vice versa" is called Thayer's Law.

Countershading is widely used by both terrestrial and marine animals. Examples include deer and sharks.

Countershading is relatively seldom used for military camouflage, despite Second World War experiments that demonstrated its effectiveness. English Zoologist Hugh B. Cott encouraged the use of techniques including countershading to provide effective concealment, observing that soldiers viewed camouflage netting as "some kind of invisibility cloak: just throw it over the truck and now you don't see it", as Peter Forbes comments. At the same time in Australia, zoologist William John Dakin advised soldiers to copy animals' methods, using their instincts for wartime camouflage.

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  Countershaded Reef Shark, Carcharhinus amblyrynchos

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  Countershaded US Navy Vigilante aircraft in jungle colours

Crypsis by counterillumination

Counterillumination means producing light to match the background, notably in some species of Squid, such as the Sparkling Enope Squid (Watasenia scintillans) and the Midwater Squid (Abralia veranyi). Abralia has light-producing organs (photophores) scattered all over its underside; these create a sparkling glow that prevents the animal from appearing as a dark shape when seen from below.

Counterillumination is the likely function of the bioluminescence of many marine organisms, though light is also produced to attract prey and for signalling.

Counterillumination has rarely been used for military purposes. Diffused lighting camouflage, in which light was projected on to the sides of ships to match the faint glow of the night sky, was trialled by Canada's National Research Council during World War II. The Canadian concept was trialled in American aircraft including B-24 Liberators, using forward-pointing lamps automatically adjusted to match the brightness of the sky.

The Sparkling Enope Squid uses Bioluminescence to make its underside as bright as the sea surface above it

Dazzle patterning

Further information: Military camouflage, Dazzle camouflage, and Ship camouflage

Most forms of camouflage are made ineffective by movement: a deer or grasshopper may be highly cryptic when motionless, but instantly seen when it moves. But one form of 'camouflage' works only when in motion: dazzle patterning.

Military dazzle 'camouflage'

Dazzle patterning superficially resembles disruptive patterning, but has a different purpose. It was used on ships during the First World War, not to make vessels hard to see, but to make their speed, size, range and direction difficult to ascertain by eye. Dazzle patterning is therefore arguably (by definition) not camouflage, though it has been called camouflage since the First World War. Non-aligning dazzle patterns may have helped to confuse gunners using optical rangefinders, where two halves of the image had to be aligned by eye to estimate the range to the target ship. However the evidence for its success in naval warfare is mixed. Remarkably, some United States Navy camouflage schemes in World War II attempted to combine disruptive camouflage and dazzle.

Motion dazzle

Motion dazzle is caused by rapidly-moving bold patterns of contrasting stripes, as when zebras run from a lion. Motion dazzle may degrade predators' ability to estimate the prey's speed and direction accurately, giving the prey an improved chance of escape. Motion dazzle distorts speed perception, and is most effective at high speeds; stripes can also distort perception of size (and so, perceived range to the target). Since dazzle patterns (such as a zebra's stripes) make animals more difficult to locate accurately when moving, but easier to see when stationary, there is an evolutionary trade-off between dazzle and crypsis.

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  A troopship painted with Dazzle camouflage to confuse enemy gunners as to her speed, direction, and range

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  The zebra's bold pattern may momentarily confuse predators, especially when many animals are close together and moving rapidly

See also

• Active camouflage
• Animal coloration (including mechanisms of colour production in animals)
• Antipredator adaptation
• Aposematism
• Mimicry
• Military camouflage
• Motion camouflage
• Underwater camouflage and mimicry

Bibliography

Camouflage in nature

Pioneering research

• Hugh Cott. Adaptive Coloration in Animals. Methuen, London, 1940.
• E. B. Poulton. The Colours of Animals. London, 1890.
• Thayer, Abbott H. and G. H. Thayer. Concealing Colouration in the Animal Kingdom. New York, 1909.

Recent research

• Stevens, Martin and and Sami Merilaita (editors). Animal Camouflage: Mechanisms and Function. Cambridge University Press, 2011.
• Stevens, Martin and Innes C Cuthill, Amy M.M Windsor, and Hannah J Walker, Disruptive contrast in animal camouflage. Proceedings of the Royal Society B: Biological Sciences. 2006 October 7; 273(1600): 2433–2438. Published online 2006 July 5. doi: 10.1098/rspb.2006.3614 Whole Text

General reading

• Behrens, Roy R. False Colors: Art, Design and Modern Camouflage. Bobolink Books, 2002. ISBN 0-97132-440-9.
• Behrens, Roy R. Camoupedia: A Compendium of Research on Art, Architecture and Camouflage. Bobolink Books, 2009. ISBN 978-0-9713244-6-8.
• Elias, Ann. Camouflage Australia: Art, Nature, Science and War. Sydney University Press, 2011. ISBN 9781920899738.
• Forbes, Peter. Dazzled and Deceived: Mimicry and Camouflage. Yale, 2009.
• Wickler, W. Mimicry in plants and animals. McGraw-Hill, 1968.

Children's books

• Kalman, B. and J. Crossingham. What are Camouflage and Mimicry?. Crabtree Publishing. (ages 4-8)
• Mettler, Rene. Animal Camouflage. Moonlight Publishing. First Discovery series, 2001. (ages 4-8)

Military camouflage

• Behrens, Roy R., ed. Ship Shape: A Dazzle Camouflage Sourcebook. Bobolink Books, 2012. ISBN 978-0-9713244-7-3.
• Gooden, Henrietta. Camouflage and Art: Design for Deception in World War 2. Unicorn Press, 2009. ISBN 978-0-906290-87-2.
• Latimer, Jon. Deception in War. John Murray, 2001.
• Newark, Tim. Camouflage. Thames and Hudson, with Imperial War Museum, 2007. ISBN 978-0-500-51347-7.

External links

• Marine Biological Laboratory: Roger Hanlon - videos, photographs, research bibliography
• Roy R. Behrens, "The Thinking Eye: a Chronology of Camouflage" 2006
• "An informal study into camouflage"
• Octopus camouflage video