The
theoretical basis for camouflage is the underlying methodology used in by
camouflageCamouflage is a method of crypsis that allows an otherwise visible organism or object to remain indiscernible from the surrounding environment through deception. Examples include a tiger's stripes and the battledress of a modern soldier...
, whether natural or human-made. The definition of camouflage involves
concealment and
obscurity, whether applied to the natural coloration of animals, or the paint schemes used on military vehicles. The methods by which concealment or obscurity are attained share a common set of strategies intended to deceive the observer. Camouflage is not limited to the commonly encountered visual camouflage, but encompasses other senses as well.
The use of camouflage, no matter what the specific application, has certain basic requirements that must be met. First, the camouflage must be tailored to the observer. Second, the camouflage must deceive the observer into making a false judgment about the camouflaged object. The strategies of camouflage can be broken down into up to four categories, which are cryptic, disruptive, mimicry, and countershading. Each of these deals with a different method of deceiving the observer, and often strategies are combined increase their effectiveness. A
tigerThe tiger is a member of the Felidae family; the largest of the four "big cats" in the genus Panthera. Native to much of eastern and southern Asia, the tiger is an apex predator and an obligate carnivore...
's distinctive coloration, for example, uses a combination of countershading and cryptic colors and patterns to blend into its environment.
Human use of camouflage
Humans have been practicing the art of camouflage since prehistoric times, as evidenced by depictions of camouflage use in cave paintings. Among humans, camouflage is of particular importance to the military, where the art of camouflage is as important as marksmanship. United States Army
field manual__FORCETOC__Field Manual is the second solo album by Death Cab for Cutie guitarist Chris Walla, released on January 29, 2008 on Barsuk Records. The album is Walla's first under his own name...
FM 5-20 states in chapter 1:
Camouflage uses concealment and deception to promote our offensive action, to surprise, to mislead the enemy, and to prevent him from inflicting damage upon us. Concealment includes hiding from view, making hard to see clearly, arranging obstructions to vision, deceiving and disguising, and deception involving sound.
Painters and other visual
artistThe definition of an artist is wide-ranging and covers a broad spectrum of activities to do with creating art, practicing the arts and/or demonstrating an art. the worlds best artist is a man named mitchell peter lay who is often loved by the ladies. The common useage in both everyday speech and...
s are sometimes employed in the development of camouflage, because they often deal with human visual perception, and it was an American artist,
Abbott Handerson ThayerAbbott Handerson Thayer was an American artist, naturalist and teacher. As a painter of portraits, figures, animals and landscapes, he enjoyed a certain prominence during his lifetime, as shown by the fact that his paintings are in the most important U.S. art collections...
, who first published a scientific paper in 1892 describing the countershading technique (see below) often found in natural camouflage. While camouflage has been used for hunting, from when prehistoric hunters dressed in animal skins to mimic their prey, to the
ScottishScotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
gamekeeperA gamekeeper is a person who looks after an area of countryside to make sure there is enough game for shooting, or fish for angling, and who actively manages areas of woodland, moorland, waterway or farmland for the benefit of game birds, deer, fish and wildlife in general.Typically, a gamekeeper...
s'
ghillie suitA ghillie suit, or yowie suit, is a type of camouflage clothing designed to resemble heavy foliage. Typically, it is a net or cloth garment covered in loose strips of cloth or twine, sometimes even made to look like leaves and twigs...
s still worn by hunters and
sniperA sniper is a highly trained marksman who shoots targets from concealed positions or distances exceeding the capabilities of regular personnel. Snipers typically have specialized training and distinct high-precision rifles...
s today, camouflage in a military context was considered effeminate and greeted with scorn in the late 19th century.
Military camouflage did not achieve widespread use until
World War IWorld War I , also known as the First World War, the Great War, and the War to End All Wars, was a global military conflict which involved most of the world's great powers, assembled in two opposing alliances: the Triple Entente and the Triple Alliance...
, after the introduction of airplanes for observation made its use far more important.
FrenchFrance , officially the French Republic , is a country located in Western Europe, with several overseas islands and territories located on other continents. Metropolitan France extends from the Mediterranean Sea to the English Channel and the North Sea, and from the Rhine to the Atlantic Ocean...
gun crews wore smocks smeared with brown and green paint to break up their outlines and provide concealment from the aerial observers; it is likely that the first soldiers to try this were artists serving in the infantry. Upon seeing a camouflaged cannon for the first time, artist
Pablo PicassoPablo Diego José Francisco de Paula Juan Nepomuceno María de los Remedios Cipriano de la Santísima Trinidad Ruiz y Picasso was a Spanish painter, draughtsman, and sculptor. Commonly known simply as Picasso, he is one of the most recognized figures in 20th-century art...
is reported to have said,
C'est nous qui avons fait ca, or
it is we who have created that. This early camouflage was not restricted to just coloring, it applied to shape as well; at an early demonstration by the American Camouflage Corps, President
Woodrow WilsonThomas Woodrow Wilson was the 28th President of the United States. A leading intellectual of the Progressive Era, he served as President of Princeton University from 1902 to 1910, and then as the Governor of New Jersey from 1911 to 1913...
approached within ten feet of a soldier without noticing him. The soldier was in a foxhole covered by a
papier-mâchéPapier-mâché , sometimes called paper-mâché, is a construction material that consists of pieces of paper, sometimes reinforced with textiles, stuck together using a wet paste...
cover camouflaged as a rock.
Camouflage in nature
Many plants and animals possess some form of camouflage, for many reasons. Natural camouflage can involve many different senses, including sight, smell, touch, and sound. The reasons for camouflage are primarily to deceive predators or prey, but camouflage can serve to aid reproduction. Some animals are even capable of adapting their appearance to match their environment. A few examples of varied strategies in camouflage are:
- Deceiving prey
- Copperhead
Copperhead may refer to:Snakes:* Agkistrodon contortrix, a venomous pit viper species found in parts of North America.* Agkistrodon piscivorus, a.k.a. the cottonmouth, another venomous pit viper species found in North America....
snakes lure prey with a worm-like tail
- Praying mantises resemble the plants on which they lie in wait, resembling leaves or even flowers
- Deceiving predators
- The gopher snake acts like a rattlesnake
Rattlesnakes are a group of venomous snakes, genera Crotalus and Sistrurus. They belong to the subfamily of venomous snakes known commonly as pit vipers.-Overview:...
when threatened, coiling up and vibrating its tail in the brush to imitate the sound of a rattle
- Some octopus
The octopus is a cephalopod of the order Octopoda. The octopus inhabits many diverse regions of the ocean, especially coral reefs. The term may also be used to refer only to those creatures in the genus Octopus...
es behave like a ball of algaeAlgae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms. The largest and most complex marine forms are called seaweeds. They are photosynthetic, like plants, and "simple" because they lack the many distinct organs found in...
, curling into a ball and rolling along the sea floor
- Vivid patterns such as the zebra
Zebras are African equids best known for their distinctive white and black stripes. Their stripes come in different patterns unique to each individual. They are generally social animals and can be seen in small harems to large herds. In addition to their stripes, zebras have erect, mohawk-like manes...
's stripes serve to confuse predators' perceptions, allowing the zebra to escape capture
- Aiding in reproduction
- The Titan arum
The titan arum or Amorphophallus titanum is a flowering plant with the largest unbranched inflorescence in the world...
, or corpse flower, emits the smell of rotting meat to attract carrion flies for pollination.
- Some species of flower mimic the smell and feel of female insects to lure male insects for pollination, a strategy called pseudocopulation
Pseudocopulation describes behaviors similar to copulation that serve a reproductive function for one or both participants but do not involve actual sexual union between the individuals. It is most generally applied to a pollinator attempting to copulate with a flower. Some flowers mimic a...
.
- Adaptive camouflage
- Some animals, such as the Arctic Fox
The Arctic Fox , also known as the White Fox or Snow Fox, is a small fox native to cold Arctic regions of the Northern Hemisphere and is common throughout the Arctic tundra biome...
, moultIn biology, moulting signifies the manner in which an animal routinely casts off a part of its body , either at specific times of year, or at specific points in its life-cycle.Moulting can involve the epidermis , pelage In biology, moulting (or molting, also known as sloughing, shedding or for...
to change color with the seasons
- Some fish
A fish is any aquatic vertebrate animal that is typically ectothermic , covered with scales, and equipped with two sets of paired fins and several unpaired fins...
obtain their color from the coralCorals are marine organisms from the class Anthozoa and exist as small sea anemone-like polyps, typically in colonies of many identical individuals...
they eat, allowing them to adapt to the local background colors
Strategies of camouflage
Camouflage is an attempt to avoid observation, and as such, it is tailored to the vision of the expected observer. In military contexts, in particular, this is not limited to normal biological vision, but applies to night vision systems, radar, and arguably sonar as well. Camouflage strategies can be broken down into four categories: cryptic (or blending), disruptive (or dazzle), mimicry, and countershading. These may be applied individually, or in combination with one another to provide an overall camouflage strategy. For example, the blending of disruptive and cryptic coloration is called
coincident disruption.
Cryptic
Cryptic camouflage is an attempt to blend into the environment and become effectively imperceptible. To do this, the camouflaged object must minimize observable differences between itself and the background with respect to the senses of the target observer. The definitive example of camouflage is a cryptic camouflage designed to match the visual appearance of the expected background, generally using a mottled pattern of greens and browns to match ground and foliage color and break up the outline of the camouflaged object.
Blending into the background is a complex task in cases where the camouflage is to be effective in a wide range of environments; camouflage that works in the arctic, for example, is unlikely to work in the jungle, or in the desert. Cryptic camouflage must match the colors and spatial frequencies of the background to be effective, and may have to suppress non-visual cues as well.
Nature provides some extremely effective examples of cryptic camouflage, one example of which is the class of insects generally referred to as
stick insects or
walking sticks. They are of the
orderIn scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
PhasmatodeaThe Phasmatodea are an order of insects, whose members are variously known as stick insects , walking sticks or stick-bugs , phasmids, ghost insects and leaf insects...
, which derives from the
GreekGreek , an independent branch of the Indo-European family of languages, is the language of the Greeks. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. In its ancient form, it is the language of classical...
phasma, meaning
phantom or
appirition. Their cryptic camouflage matches both the coloration and shape of the plants in their environment, and they take the form of twigs, bark, leaves or lichen, depending on species.
A good example of cryptic camouflage applied to another sense is the insect repellant
DEETN,N-Diethyl-meta-toluamide, abbreviated DEET, is a slightly yellow oil. It is the most common active ingredient in insect repellents. It is intended to be applied to the skin or to clothing, and is primarily used to repel mosquitoes...
. DEET is believed to work by blocking insect olfactory receptors for
1-octen-3-ol1-Octen-3-ol, octenol for short , is a chemical that attracts biting insects such as mosquitos. It is contained in human breath and sweat, and it was once believed that insect repellent DEET works by blocking the insects' octenol odorant receptors.Octenol is used in combination with carbon dioxide...
, a secondary alcohol produced by humans and emitted by perspiration and
respirationIn animal physiology, respiration is the transport of oxygen from the outside air to the cells within tissues, and the transport of carbon dioxide in the opposite direction...
. By blocking the receptors, it makes the wearer effectively undetectable to
mosquitoMosquito is a common insect in the family Culicidae...
es,
tickTick is the common name for the small arachnids in superfamily Ixodoidea that, along with other mites, constitute the Acarina. Ticks are ectoparasites , living by hematophagy on the blood of mammals, birds, and occasionally reptiles and amphibians...
s, and many other insects that rely on olfactory cues to find their targets.
Disruptive
Disruptive camouflage is not intended to blend into the environment, and in fact often involves bright, eye-catching colors that would be the antithesis of cryptic camouflage. Disruptive camouflage seeks to confuse the observer, by providing visual cues that override the camouflaged object's features. This prevents the observer from accurately identifying characteristics of the camouflaged object(s), such as shape, size, orientation, and number of objects in a group.
Another form of disruptive camouflage is ink used by octopuses, or smoke used by the military to obscure movement. The cloud of ink or smoke is readily visible, but obscures what is within or behind it. The likely root of the word
camouflage is
camouflet, a
FrenchFrench is a Romance language globally spoken by about 65 million people as a first language , by 50 million as a second language, and by about another 200 million people as an acquired foreign language, with significant speakers in 57 countries. Most native speakers of the language live in France,...
term meaning
smoke blown in someone's face as a practical joke. In the case of the octopus ink, the resulting cloud also provides disruption of the sense of smell.
Mimicry
Mimicry is the attempt by the camouflaged object to be observed as some other type of object. In some cases this can be quite a complex process, such as in the case of the
Mimic OctopusThe mimic octopus, Thaumoctopus mimicus, is a species of octopus that has a strong ability to mimic other creatures. It grows up to 60 cm in length. Its normal colouring consists of brown and white stripes or spots....
, which can change shape to resemble
lionfishA Lionfish is any of several species of venomous marine fish in the genera Pterois, Parapterois, Brachypterois, Ebosia or Dendrochirus, of the family Scorpaenidae. The lionfish is also known as the Turkey Fish, Dragon Fish, Scorpion or Fire Fish...
or other poisonous fish in its habitat. Mimicry is perhaps the broadest example of camouflage; though the most obvious form to humans is visual mimicry, other senses, such as
olfactionOlfaction refers to the sense of smell. This sense is mediated by specialized sensory cells of the nasal cavity of vertebrates, and, by analogy, sensory cells of the antennae of invertebrates...
(smell) or
hearingHearing is one of the traditional five senses. It is the ability to perceive sound by detecting vibrations via an organ such as the ear...
may be involved as well.
- The Titan arum
The titan arum or Amorphophallus titanum is a flowering plant with the largest unbranched inflorescence in the world...
, or corpse flower, emits the smell of rotting meat to attract carrion flies for pollination.
- The False Cobra
The false cobra is an opisthoglyphous snake found in parts of Asia. The name "False Cobra" comes from the fact that this is not a cobra. It imitates a cobra's stance by spreading its neck into a hood and hissing like the cobra...
mimics the hood and aggressive stance of the highly poisonous cobraA cobra is a venomous snake, which is a member of the family Elapidae . The name is short for cobra de capelo , which is Portuguese for "snake with hood," or "hood-snake." When disturbed, most of these snakes can rear up and spread their neck in a characteristic threat display...
to deter predators.
- Some species of flower mimic the smell and feel of female insects to lure male insects for pollination, a strategy called pseudocopulation
Pseudocopulation describes behaviors similar to copulation that serve a reproductive function for one or both participants but do not involve actual sexual union between the individuals. It is most generally applied to a pollinator attempting to copulate with a flower. Some flowers mimic a...
.
DecoyA decoy is usually a person, device or event meant as a distraction to conceal what an individual or a group might be looking for. Decoys have been used for centuries most notably in game hunting, but also in wartime and in the committing or resolving of crimes.The decoy in war may for example be a...
s and
fishing lureIn terms of recreational fishing, a lure is an object attached to the end of the fishing line and designed to resemble and move like an item of fish prey. The purpose of the lure is to use movement, vibrations, and color to catch the fish's attention to make them bite the hook...
s also utilize mimicry to deceive and lure an observer. Some animals, such as the
anglerfishAnglerfish are the members of the order Lophiiformes . They are bony fish named for their characteristic mode of predation, wherein a fleshy growth from the fish's head acts as a lure; this is considered analogous to angling.Some anglerfish are pelagic , others are benthic...
, use part of their body to lure prey into range, while human hunters use decoys to lure targets into a
killing fieldA killing field, in military science, is an area in front of a defensive position that the enemy must cross during an assault and is specifically intended to allow the defending troops to incapacitate a large number of the enemy. Defensive emplacements such as anti-tank obstacles, barbed wire and...
. Decoys are also used by the military, typically to draw enemy fire to the decoy, and away from the real target.
Countershading
Also called Thayer's Law, a tribute to the artist who first described it, countershading is the process of using lighter colors on normally dark areas, and darker colors on normally light areas. This removes some of the visual cues used for
depth perceptionDepth perception is the visual ability to perceive the world in three dimensions. Although any animal capable of moving around its environment must be able to sense the distance of objects in that environment, the term perception is reserved for humans, who are, as far as is known, the only beings...
, causing the countershaded object to appear flat, rather than as an object with depth. This is the same effect used in the
hollow-face illusionThe Hollow-Face illusion is an optical illusion in which the perception of a concave mask of a face appears as a normal convex face.While a convex face will appear to look in a single direction, and a flat face such as the Lord Kitchener Wants You poster can appear to follow the moving viewer, a...
, where a concave object is shaded in such a way as to appear convex. Military doctrine also applies this technique to camouflage paint. The standard method for applying camouflage paint to exposed skin is to use dark paint for bright areas of the face, light paint for shadowed areas, and combining this with a disruptive pattern over large areas of skin.
Visual elements of camouflage
EyeEyes are organs that detect light, and send electrical impulses along the optic nerve to the visual and other areas of the brain. Complex optical systems with resolving power have come in ten fundamentally different forms, and 96% of animal species possess a complex optical system...
s differ widely across the animal kingdom. Some animals see in monochrome, perceiving only brightness, while other see two or, like humans, three types of color; some species of
birdBirds are winged, bipedal, endothermic , vertebrate animals that lay eggs. There are around 10,000 living species, making them the most numerous tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Birds range in size from the Bee Hummingbird to the ...
s and
reptileReptiles, or members of the class Reptilia, are air-breathing, generally "cold-blooded" amniotes that generally have skin covered in scales or scutes. They are tetrapods and lay amniote eggs, whose embryos are surrounded by the amnion membrane...
s are capable of distinguishing four different colors. Even in animals with the same degree of color perception, the
pigmentA pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...
s respond to different
wavelengthIn physics, the wavelength of a sinusoidal wave is the spatial period of the wave – the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...
s, meaning what would appear to be a
metamerIn colorimetry, metamerism is the matching of apparent color of objects with different spectral power distributions. Colors that match this way are called metamers....
to one species would be a completely different color to another species.
In addition to differences in how color is perceived, the
nervous systemThe nervous system is a network of specialized cells that communicate information about an organism's surroundings and itself. It processes this information and causes reactions in other parts of the body. It is composed of neurons and other specialized cells called glial cells that aid in the...
does a significant amount of processing to the image, finding edges, adjusting contrast, and determining spatial frequency.
Perception of color and brightness
Normal humans (excluding individuals who have a form of colorblindness) see though the actions of four types of receptors in the eye; the rods, which are highly sensitive, perceive brightness, while three types of cones perceive red, green, and blue colors. Humans, and most primates, are trichromats, able to perceive three types of color. The density and sensitivity of these rods and cones determine how sensitive the eye is to color. Brightness is the most important factor, followed by green, red, and blue colors, in that order. Sometimes unexpected colors provide good cryptic coloration, such as pink. A shade called
Mountbatten pinkMountbatten Pink, also called Plymouth Pink, is a naval camouflage color, a shade of mauve, invented by Louis Mountbatten of the British Royal Navy in autumn 1940 during World War II....
was used during
World War IIWorld War II, or the Second World War , was a global military conflict which involved a majority of the world's nations, including all great powers, organized into two opposing military alliances: the Allies and the Axis...
for ships when it was discovered that it disappeared against the morning and evening skies, and the
Special Air ServiceThe Special Air Service is a special forces regiment within the British Army which has served as a model for the special forces of other countries. The SAS forms a significant section of United Kingdom Special Forces alongside the Special Boat Service , Special Reconnaissance Regiment , and the...
used pink as the primary color on the
desertA desert is a landscape or region that receives almost no precipitation. Deserts are defined as areas with an average annual precipitation of less than per year, or as areas where more water is lost by evapotranspiration than falls as precipitation. In the Köppen climate classification system,...
camouflaged Land Rover Series IIA patrol vehicles, leading to the nickname
The Pink
Panthers.
Color perception in animals varies by species; most
mammalMammals are a class of vertebrate animals whose females are characterized by the possession of mammary glands while both males and females are characterized by sweat glands, hair, three middle ear bones used in hearing, and a neocortex region in the brain.Mammals are divided into three main...
s are dichromats, perceiving two colors.
DeerDeer are the ruminant mammals forming the family Cervidae. They include for example Moose, Red Deer, Reindeer, Roe and Chital. Animals from related families within the order Artiodactyla are often also considered to be deer – these include muntjac and water deer...
, for example, see blue and yellow, but not red, and their perception of blue is far broader and more acute than humans. A camouflage garment laundered in typical laundry detergent laced with
ultravioletUltraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than x-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
dyeA dye can generally be described as a colored substance that has an affinity to the substrate to which it is being applied. The dye is generally applied in an aqueous solution, and may require a mordant to improve the fastness of the dye on the fiber....
, added to brighten colors, may blend into the background when seen with the human eye, but the deer's eyes are sensitive into the near ultraviolet portion of the spectrum, and the garment will stand out as a brightly colored object. Orange and red, however, are far enough from the deer's yellow receptor range that they will appear as dim colors, so what a human sees as a bright orange element in a camouflage pattern will appear as a dark color to the deer's eye. Similarly, the rods of deer are sensitive further into the near ultraviolet than are human eyes (though still lacking in response at the red end of the spectrum), and provide a greater response. This gives
deer superior vision in low light conditions. Birds, on the other hand, do see red, and near ultraviolet; both ultraviolet dyes and blaze orange will be visible to them.
Perception of shapes and edges
Spatial frequencyIn mathematics, physics, and engineering, spatial frequency is a characteristic of any structure that is periodic across position in space. The spatial frequency is a measure of how often the structure repeats per unit of distance. The SI unit of spatial frequency is cycles per meter...
perceptors in the eyes of many animals allow easy identification of mismatched spatial frequencies. By matching the spatial frequency of the background, such as a tiger's stripes, the camouflaged object can blend in; by not matching it, such as with the zebra's stripes, the camouflaged object can stand out.
Perception of movement
Vision, in animals from
fliesThe housefly , Musca domestica, is the most common of all flies found in homes, and indeed one of the most widely distributed insects, found all over the world; it is often considered a pest that can carry serious diseases.- Physical description :The adults are 8–12 mm long...
to humans, has special processing mechanisms for detection of motion. Motion will destroy the illusion of even otherwise perfect cryptic camouflage, so objects relying on cryptic camouflage must remain very nearly stationary with respect to their environment. This does not apply to other camouflage strategies; the disruptive form of camouflage, for example, was applied to ships in the form of dazzle camouflage, providing a more effective camouflage for the moving ships than a cryptic strategy. Octopus ink and smoke screens are other forms of camouflage that can effectively be used to conceal movement.
Non-vision camouflage
Many animals rely far more on senses other than sight, so when attempting to deceive these animals, it is important to consider other senses. An example of this is the wide range of products available to the hunter to deal with the issue of scent. These can range from scent blocking clothing, which serves as a cryptic form of camouflage, to scents that mimic plant, animal, and food scents, designed to mask the hunter's scent or lure the game in.
Clothing can also provide a cryptic camouflage with respect to sound. Certain fabrics, such as
cottonCotton is a soft, staple fiber that grows in a form known as a boll around the seeds of the cotton plant, a shrub native to tropical and subtropical regions around the world, including the Americas, India and Africa. The fiber most often is spun into yarn or thread and used to make a soft,...
/
nylonNylon is a generic designation for a family of synthetic polymers known generically as polyamides and first produced on February 28, 1935 by Wallace Carothers at DuPont...
blends, create a significant amount of sound when rubbed together, or against other objects. Other fabrics, such as
polar fleecePolar fleece , usually referred to simply as "fleece," is a soft napped insulating synthetic wool fabric made from PET or other synthetic fibres. One of the first forms was Polar Fleece created in 1979 by Malden Mills, now Polartec LLC., a new, light and strong pile fabric meant to mimic and in...
and many all natural fiber fabrics, are much quieter, and will reduce the amount of noise generated by movement. Game calls are used as a form of mimicry, with calls existing that mimic the sounds of everything from
duckDuck is the common name for a number of species in the Anatidae family of birds. The ducks are divided between several subfamilies listed in full in the Anatidae article; they do not represent a monophyletic group but a form taxon, since swans and geese are not considered ducks...
s and
geeseThe word Goose is the English name for a considerable number of birds, belonging to the family Anatidae. This family also includes swans, most of which are larger than true geese, and ducks, which are smaller....
to
bearBears are mammals of the family Ursidae. Bears are classified as caniforms, or doglike carnivorans, with the pinnipeds being their closest living relatives. Although there are only eight living species of bear, they are widespread, appearing in a wide variety of habitats throughout the Northern...
s and
coyoteThe coyote , the American jackal or the prairie wolf, is a species of canid found throughout North and Central America, ranging from Panama in the south, north through Mexico, the United States and Canada...
s. These calls range from simple reed instruments that mimic a duck's
quack to remote controlled electronic playback devices that provide the user with a menu-driven selection of digitally recorded sounds.
Camouflage against technological observation
RadarRadar is an object detection system that uses electromagnetic waves to identify the range, altitude, direction, or speed of both moving and fixed objects such as aircraft, ships, motor vehicles, weather formations, and terrain. The term RADAR was coined in 1941 as an acronym for RAdio Detection And...
,
sonarSonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels. There are two kinds of sonar: active and passive. Sonar may be used as a means of acoustic location and of measurement of the echo characteristics of "targets" in the water...
,
night visionNight vision is the ability to see in a dark environment. Whether by biological or technological means, night vision is made possible by a combination of two approaches: sufficient spectral range, and sufficient intensity range...
, and thermal imaging are all common forms of observation, and just like natural senses, camouflage exists in many forms to deceive these technological senses. Camouflage may be implemented by cryptic means, such as
stealth technologyStealth technology also known as LO technology is a sub-discipline of military tactics and passive electronic countermeasures , which cover a range of techniques used with personnel, aircraft, ships, submarines, and missiles, in order to make them less visible to radar, infrared , sonar and other...
applied to military vehicles, by disruptive means, such as
radar jamming and deceptionRadar jamming and deception is the intentional emission of radio frequency signals to interfere with the operation of a radar by saturating its receiver with noise or false information...
, or mimicry means, such as the decoys like the
AN/SLQ-25 NixieThe AN/SLQ-25 Nixie and its variants are towed torpedo decoys used on US and allied warships. It consists of a towed decoy device and a shipboard signal generator...
and anti-missile
flaresA flare is an aerial infrared countermeasure to counter an infrared homing surface-to-air missile or air-to-air missile. Flares are commonly composed of a pyrotechnic composition based on magnesium or another hot-burning metal, with burning temperature equal to or hotter than engine exhaust...
.
In the more traditional sense of camouflage, there has even been camouflage clothing designed to help defeat technological detection. The US military issued a pattern that consisted of a grid of darker green lines on a spotted, dark green background, that was designed to confuse early night vision devices. There is also a thermal camouflage cream under development, that reduces thermal infrared emissions from bare skin. Tests have shown a five times or greater reduction in detection range when this cream is applied to exposed skin.
Adaptive camouflage
Chameleons and some octopuses have the ability to alter their color through the use of chromatophores which allow the animal to change the type and amount of light reflected. This is a form of adaptive or active camouflage. Research is being done into military adaptations of adaptive cryptic camouflage, using sensors and adaptive coloration to sense and adapt the coloration of an object to better match its background.