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Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the
leopard The leopard (''Panthera pardus'') is one of the five extant cat species in the genus ''Panthera''. It has a pale yellowish to dark golden fur with dark spots grouped in rosettes. Its body is slender and muscular reaching a length of with a ...
's spotted coat, the
battledress A combat uniform, also called a field uniform, battledress, or fatigues, is a casual wear, casual uniform used by military, police, firefighter, fire, and other public uniformed services for everyday fieldwork and duty, as opposed to dress uni ...
of a modern
soldier A soldier is a person who is a member of an army. A soldier can be a Conscription, conscripted or volunteer Enlisted rank, enlisted person, a non-commissioned officer, a warrant officer, or an Officer (armed forces), officer. Etymology The wo ...
, and the leaf-mimic katydid's wings. A third approach, motion dazzle, confuses the observer with a conspicuous pattern, making the object visible but momentarily harder to locate. The majority of camouflage methods aim for
crypsis In ecology, crypsis is the ability of an animal or a plant to avoid observation or detection by other animals. It may be part of a predation strategy or an antipredator adaptation. Methods include camouflage, nocturnality, subterranean life ...
, often through a general resemblance to the background, high contrast
disruptive coloration Disruptive coloration (also known as disruptive camouflage or disruptive patterning) is a form of camouflage that works by breaking up the outlines of an animal, soldier or military hardware with a strongly contrasting pattern. It is often com ...
, eliminating shadow, and
countershading Countershading, or Thayer's law, is a method of camouflage in which animal coloration, an animal's coloration is darker on the top or upper side and lighter on the underside of the body. This pattern is found in many species of mammals, reptile ...
. In the open ocean, where there is no background, the principal methods of camouflage are transparency, silvering, and countershading, while the ability to produce light is among other things used for
counter-illumination Counter-illumination is a method of active camouflage seen in marine animals such as firefly squid and midshipman fish, and in military prototypes, producing light to match their backgrounds in both brightness and wavelength. Marine animals of ...
on the undersides of
cephalopod A cephalopod is any member of the molluscan Taxonomic rank, class Cephalopoda (Greek language, Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral symm ...
s such as
squid A squid (: squid) is a mollusc with an elongated soft body, large eyes, eight cephalopod limb, arms, and two tentacles in the orders Myopsida, Oegopsida, and Bathyteuthida (though many other molluscs within the broader Neocoleoidea are also ...
. Some animals, such as
chameleon Chameleons or chamaeleons (Family (biology), family Chamaeleonidae) are a distinctive and highly specialized clade of Old World lizards with 200 species described as of June 2015. The members of this Family (biology), family are best known for ...
s and
octopus An octopus (: octopuses or octopodes) is a soft-bodied, eight-limbed mollusc of the order Octopoda (, ). The order consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttlefish, and nautiloids. Like oth ...
es, are capable of actively changing their skin pattern and colours, whether for camouflage or for signalling. It is possible that some plants use camouflage to evade being eaten by
herbivore A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat ...
s.
Military camouflage Military camouflage is the use of camouflage by an Military, armed force to protect personnel and equipment from observation by enemy forces. In practice, this means applying colour and materials to military equipment of all kinds, including ...
was spurred by the increasing range and accuracy of firearms in the 19th century. In particular the replacement of the inaccurate
musket A musket is a muzzle-loaded long gun that appeared as a smoothbore weapon in the early 16th century, at first as a heavier variant of the arquebus, capable of penetrating plate armour. By the mid-16th century, this type of musket gradually dis ...
with the
rifle A rifle is a long gun, long-barreled firearm designed for accurate shooting and higher stopping power, with a gun barrel, barrel that has a helical or spiralling pattern of grooves (rifling) cut into the bore wall. In keeping with their focus o ...
made personal concealment in battle a survival skill. In the 20th century, military camouflage developed rapidly, especially during the
World War I World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...
. On land, artists such as
André Mare Charles André Mare (1885–1932), or André-Charles Mare, was a French painter and textile designer, and co-founder of the Company of French Art (''la Compagnie des Arts Français'') in 1919. He was a designer of colorful textiles, and was one o ...
designed camouflage schemes and observation posts disguised as trees.
At sea A sea is a large body of salt water. There are particular seas and the sea. The sea commonly refers to the ocean, the interconnected body of seawaters that spans most of Earth. Particular seas are either marginal seas, second-order section ...
, merchant ships and troop carriers were painted in
dazzle Dazzle may refer to: Arts * ''Dazzle'' (manga), a Japanese manga by Minari Endoh * "Dazzle" (song), by the English post-punk band Siouxsie and the Banshees * The Dazzle Dancers, a performance group founded in 1996 * " Dazzle Dazzle", a song by ...
patterns that were highly visible, but designed to confuse enemy submarines as to the target's speed, range, and heading. During and after
World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
, a variety of camouflage schemes were used for
aircraft An aircraft ( aircraft) is a vehicle that is able to flight, fly by gaining support from the Atmosphere of Earth, air. It counters the force of gravity by using either Buoyancy, static lift or the Lift (force), dynamic lift of an airfoil, or, i ...
and for ground vehicles in different theatres of war. The use of radar since the mid-20th century has largely made camouflage for fixed-wing military aircraft obsolete. Non-military use of camouflage includes making cell telephone towers less obtrusive and helping hunters to approach wary game animals. Patterns derived from military camouflage are frequently used in fashion clothing, exploiting their strong designs and sometimes their symbolism. Camouflage themes recur in modern art, and both figuratively and literally in science fiction and works of literature.


History


Classical antiquity

In ancient Greece,
Aristotle Aristotle (; 384–322 BC) was an Ancient Greek philosophy, Ancient Greek philosopher and polymath. His writings cover a broad range of subjects spanning the natural sciences, philosophy, linguistics, economics, politics, psychology, a ...
(384–322 BC) commented on the colour-changing abilities, both for camouflage and for
signalling A signal is both the process and the result of transmission of data over some media accomplished by embedding some variation. Signals are important in multiple subject fields including signal processing, information theory and biology. In ...
, of
cephalopod A cephalopod is any member of the molluscan Taxonomic rank, class Cephalopoda (Greek language, Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral symm ...
s including the
octopus An octopus (: octopuses or octopodes) is a soft-bodied, eight-limbed mollusc of the order Octopoda (, ). The order consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttlefish, and nautiloids. Like oth ...
, in his ''
Historia animalium ''History of Animals'' (, ''Ton peri ta zoia historion'', "Inquiries on Animals"; , "History of Animals") is one of the major texts on biology by the ancient Greek philosopher Aristotle. It was written in sometime between the mid-fourth centur ...
'':


Zoology

Camouflage has been a topic of interest and research in
zoology Zoology ( , ) is the scientific study of animals. Its studies include the anatomy, structure, embryology, Biological classification, classification, Ethology, habits, and distribution of all animals, both living and extinction, extinct, and ...
for well over a century. According to
Charles Darwin Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English Natural history#Before 1900, naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all speci ...
's 1859 theory of
natural selection Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the Heredity, heritable traits characteristic of a population over generation ...
, features such as camouflage
evolved Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, re ...
by providing individual animals with a reproductive advantage, enabling them to leave more offspring, on average, than other members of the same
species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
. In his ''
Origin of Species ''On the Origin of Species'' (or, more completely, ''On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life'')The book's full original title was ''On the Origin of Species by M ...
'', Darwin wrote: The English zoologist
Edward Bagnall Poulton Sir Edward Bagnall Poulton, FRS HFRSE FLS (27 January 1856 – 20 November 1943) was a British evolutionary biologist, a lifelong advocate of natural selection through a period in which many scientists such as Reginald Punnett doubted its ...
studied
animal coloration Animal coloration is the general appearance of an animal resulting from the reflection or emission of light from its surfaces. Some animals are brightly coloured, while others are hard to see. In some species, such as the peafowl, the male h ...
, especially camouflage. In his 1890 book ''
The Colours of Animals ''The Colours of Animals'' is a zoology book written in 1890 by Sir Edward Bagnall Poulton (1856–1943). It was the first substantial textbook to argue the case for Charles Darwin, Darwinian selection applying to all aspects of animal colorati ...
'', he classified different types such as "special protective resemblance" (where an animal looks like another object), or "general aggressive resemblance" (where a
predator Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...
blends in with the background, enabling it to approach prey). His experiments showed that swallow-tailed moth
pupae A pupa (; : pupae) is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their life cycle, the stages th ...
were camouflaged to match the backgrounds on which they were reared as
larvae A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect developmental biology, development such as insects, some arachnids, amphibians, or cnidarians typical ...
. Poulton's "general protective resemblance" was at that time considered to be the main method of camouflage, as when
Frank Evers Beddard Frank Evers Beddard FRS FRSE (19 June 1858 – 14 July 1925) was an English zoologist. He became a leading authority on annelids, including earthworms. He won the Linnean Medal in 1916 for his book on oligochaetes. Life Beddard was born in ...
wrote in 1892 that "tree-frequenting animals are often green in colour. Among vertebrates numerous species of
parrot Parrots (Psittaciformes), also known as psittacines (), are birds with a strong curved beak, upright stance, and clawed feet. They are classified in four families that contain roughly 410 species in 101 genus (biology), genera, found mostly in ...
s,
iguana ''Iguana'' (, ) is a genus of herbivorous lizards that are native to tropical areas of Mexico, Central America, South America, and the Caribbean. The genus was first described by Austrian naturalist Josephus Nicolaus Laurenti, J.N. Laurenti in ...
s, tree-frogs, and the green tree-snake are examples". Beddard did however briefly mention other methods, including the "alluring coloration" of the
flower mantis Flower mantises are praying mantises that use a special form of camouflage referred to as aggressive mimicry, which they not only use to attract prey, but avoid predators as well. These insects have specific colorations and behaviors that mimic ...
and the possibility of a different mechanism in the orange tip butterfly. He wrote that "the scattered green spots upon the under surface of the wings might have been intended for a rough sketch of the small flowerets of the plant n umbellifer">umbellifer.html" ;"title="n umbellifer">n umbellifer so close is their mutual resemblance." He also explained the coloration of sea fish such as the mackerel: "Among pelagic fish it is common to find the upper surface dark-coloured and the lower surface white, so that the animal is inconspicuous when seen either from above or below." The artist
Abbott Handerson Thayer Abbott Handerson Thayer (August 12, 1849May 29, 1921) was an American painter, naturalist, and teacher. As a painter of portraits, figures, animals, and landscapes, he enjoyed a certain prominence during his lifetime, and his paintings are repres ...
formulated what is sometimes called Thayer's Law, the principle of
countershading Countershading, or Thayer's law, is a method of camouflage in which animal coloration, an animal's coloration is darker on the top or upper side and lighter on the underside of the body. This pattern is found in many species of mammals, reptile ...
. However, he overstated the case in the 1909 book '' Concealing-Coloration in the Animal Kingdom'', arguing that "All patterns and colors whatsoever of all animals that ever preyed or are preyed on are under certain normal circumstances obliterative" (that is, cryptic camouflage), and that "Not one '
mimicry In evolutionary biology, mimicry is an evolved resemblance between an organism and another object, often an organism of another species. Mimicry may evolve between different species, or between individuals of the same species. In the simples ...
' mark, not one ' warning color'... nor any ' sexually selected' color, exists anywhere in the world where there is not every reason to believe it the very best conceivable device for the concealment of its wearer", and using paintings such as ''Peacock in the Woods'' (1907) to reinforce his argument. Thayer was roundly mocked for these views by critics including
Teddy Roosevelt Theodore Roosevelt Jr. (October 27, 1858 – January 6, 1919), also known as Teddy or T.R., was the 26th president of the United States, serving from 1901 to 1909. Roosevelt previously was involved in New York politics, including serving as ...
. The English zoologist
Hugh Cott Hugh Bamford Cott (6 July 1900 – 18 April 1987) was a British zoologist, an authority on both natural and military camouflage, and a scientific illustrator and photographer. Many of his field studies took place in Africa, where he was especia ...
's 1940 book ''
Adaptive Coloration in Animals ''Adaptive Coloration in Animals'' is a 500-page textbook about camouflage, warning coloration and mimicry by the Cambridge zoologist Hugh Cott, first published during the Second World War in 1940; the book sold widely and made him famous. Th ...
'' corrected Thayer's errors, sometimes sharply: "Thus we find Thayer straining the theory to a fantastic extreme in an endeavour to make it cover almost every type of coloration in the animal kingdom." Cott built on Thayer's discoveries, developing a comprehensive view of camouflage based on "maximum disruptive contrast", countershading and hundreds of examples. The book explained how
disruptive camouflage Disruptive coloration (also known as disruptive camouflage or disruptive patterning) is a form of camouflage that works by breaking up the outlines of an animal, soldier or military hardware with a strongly contrasting pattern. It is often com ...
worked, using streaks of boldly contrasting colour, paradoxically making objects less visible by breaking up their outlines. While Cott was more systematic and balanced in his view than Thayer, and did include some experimental evidence on the effectiveness of camouflage, his 500-page textbook was, like Thayer's, mainly a
natural history Natural history is a domain of inquiry involving organisms, including animals, fungi, and plants, in their natural environment, leaning more towards observational than experimental methods of study. A person who studies natural history is cal ...
narrative which illustrated theories with examples. Experimental evidence that camouflage helps prey avoid being detected by predators was first provided in 2016, when ground-nesting birds (
plovers Plovers ( , ) are members of a widely distributed group of wading birds of subfamily Charadriinae. The term "plover" applies to all the members of the subfamily, though only about half of them include it in their name. Species list in t ...
and coursers) were shown to survive according to how well their egg contrast matched the local environment.


Evolution

As there is a lack of evidence for camouflage in the fossil record, studying the evolution of camouflage strategies is very difficult. Furthermore, camouflage traits must be both adaptable (provide a fitness gain in a given environment) and heritable (in other words, the trait must undergo
positive selection In population genetics, directional selection is a type of natural selection in which one extreme phenotype is favored over both the other extreme and moderate phenotypes. This genetic selection causes the allele frequency to shift toward the ...
). Thus, studying the evolution of camouflage strategies requires an understanding of the genetic components and various ecological pressures that drive crypsis.


Fossil history

Camouflage is a soft-tissue feature that is rarely preserved in the
fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...
record, but rare fossilised skin samples from the
Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...
period show that some marine reptiles were countershaded. The skins, pigmented with dark-coloured
eumelanin Melanin (; ) is a family of biomolecules organized as oligomers or polymers, which among other functions provide the pigments of many organisms. Melanin pigments are produced in a specialized group of cells known as melanocytes. There are ...
, reveal that both leatherback turtles and
mosasaur Mosasaurs (from Latin ''Mosa'' meaning the 'Meuse', and Ancient Greek, Greek ' meaning 'lizard') are an extinct group of large aquatic reptiles within the family Mosasauridae that lived during the Late Cretaceous. Their first fossil remains wer ...
s had dark backs and light bellies. There is fossil evidence of camouflaged insects going back over 100 million years, for example lacewings larvae that stick debris all over their bodies much as their modern descendants do, hiding them from their prey. Dinosaurs appear to have been camouflaged, as a 120 million year old fossil of a ''
Psittacosaurus ''Psittacosaurus'' ( ; "parrot lizard") is a genus of extinct ceratopsian dinosaur from the Early Cretaceous of what is now Asia, existing between 125 and 105 million years ago. It is notable for being the most species-rich non-avian dinosaur ...
'' has been preserved with
countershading Countershading, or Thayer's law, is a method of camouflage in which animal coloration, an animal's coloration is darker on the top or upper side and lighter on the underside of the body. This pattern is found in many species of mammals, reptile ...
.


Genetics

Camouflage does not have a single genetic origin. However, studying the genetic components of camouflage in specific organisms illuminates the various ways that crypsis can evolve among lineages. Many
cephalopod A cephalopod is any member of the molluscan Taxonomic rank, class Cephalopoda (Greek language, Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral symm ...
s have the ability to actively camouflage themselves, controlling crypsis through neural activity. For example, the genome of the common cuttlefish includes 16 copies of the reflectin gene, which grants the organism remarkable control over coloration and iridescence. The reflectin gene is thought to have originated through transposition from symbiotic '' Aliivibrio fischeri'' bacteria, which provide bioluminescence to its hosts. While not all cephalopods use
active camouflage Active camouflage or adaptive camouflage is camouflage that adapts, often rapidly, to the surroundings of an object such as an animal or military vehicle. In theory, active camouflage could provide perfect concealment from visual detection. Acti ...
, ancient cephalopods may have inherited the gene horizontally from symbiotic ''A. fischeri'', with divergence occurred through subsequent gene duplication (such as in the case of ''Sepia officinalis'') or gene loss (as with cephalopods with no active camouflage capabilities). /sup> This is unique as an instance of camouflage arising as an instance of
horizontal gene transfer Horizontal gene transfer (HGT) or lateral gene transfer (LGT) is the movement of genetic material between organisms other than by the ("vertical") transmission of DNA from parent to offspring (reproduction). HGT is an important factor in the e ...
from an
endosymbiont An endosymbiont or endobiont is an organism that lives within the body or cells of another organism. Typically the two organisms are in a mutualism (biology), mutualistic relationship. Examples are nitrogen-fixing bacteria (called rhizobia), whi ...
. However, other methods of horizontal gene transfer are common in the evolution of camouflage strategies in other lineages.
Peppered moth The peppered moth (''Biston betularia'') is a temperate species of Nocturnality, night-flying moth. It is mostly found in the northern hemisphere in places like Asia, Europe and North America. Peppered moth evolution is an example of populatio ...
s and walking stick insects both have camouflage-related genes that stem from transposition events. The
Agouti The agouti (, ) or common agouti is any of several rodent species of the genus ''Dasyprocta''. They are native to Central America, northern and central South America, and the southern Lesser Antilles. Some species have also been introduced else ...
genes are orthologous genes involved in camouflage across many lineages. They produce yellow and red coloration (
phaeomelanin Melanin (; ) is a family of biomolecules organized as oligomers or polymers, which among other functions provide the pigments of many organisms. Melanin pigments are produced in a specialized group of cells known as melanocytes. There are ...
), and work in competition with other genes that produce black (melanin) and brown (eumelanin) colours. In eastern deer mice, over a period of about 8000 years the single agouti gene developed 9 mutations that each made expression of yellow fur stronger under natural selection, and largely eliminated melanin-coding black fur coloration. On the other hand, all black domesticated cats have deletions of the agouti gene that prevent its expression, meaning no yellow or red color is produced. The evolution, history and widespread scope of the agouti gene shows that different organisms often rely on orthologous or even identical genes to develop a variety of camouflage strategies.


Ecology

While camouflage can increase an organism's fitness, it has genetic and energetic costs. There is a trade-off between detectability and mobility. Species camouflaged to fit a specific
microhabitat In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...
are less likely to be detected when in that microhabitat, but must spend energy to reach, and sometimes to remain in, such areas. Outside the microhabitat, the organism has a higher chance of detection. Generalized camouflage allows species to avoid predation over a wide range of habitat backgrounds, but is less effective. The development of generalized or specialized camouflage strategies is highly dependent on the biotic and abiotic composition of the surrounding environment. There are many examples of the tradeoffs between specific and general cryptic patterning. ''
Phestilla ''Phestilla'' is a genus of sea slugs, aeolid nudibranchs, marine gastropod molluscs in the family Trinchesiidae. Its members are unusual in feeding on hard corals, unlike other members of the family Trinchesiidae which feed on hydroids. Adult ...
melanocrachia'', a species of nudibranch that feeds on
stony coral Scleractinia, also called stony corals or hard corals, are marine animals in the phylum Cnidaria that build themselves a hard skeleton. The individual animals are known as polyps and have a cylindrical body crowned by an oral disc in which a mo ...
, utilizes specific cryptic patterning in reef ecosystems. The nudibranch syphons pigments from the consumed coral into the epidermis, adopting the same shade as the consumed coral. This allows the nudibranch to change colour (mostly between black and orange) depending on the coral system that it inhabits. However, ''P. melanocrachia'' can only feed and lay eggs on the branches of host-coral, '' Platygyra carnosa'', which limits the geographical range and efficacy in nudibranch nutritional crypsis. Furthermore, the nudibranch colour change is not immediate, and switching between coral hosts when in search for new food or shelter can be costly. The costs associated with distractive or disruptive crypsis are more complex than the costs associated with background matching. Disruptive patterns distort the body outline, making it harder to precisely identify and locate. However, disruptive patterns result in higher predation. Disruptive patterns that specifically involve visible symmetry (such as in some butterflies) reduce survivability and increase predation. Some researchers argue that because wing-shape and color pattern are genetically linked, it is genetically costly to develop asymmetric wing colorations that would enhance the efficacy of disruptive cryptic patterning. Symmetry does not carry a high survival cost for butterflies and moths that their predators views from above on a homogeneous background, such as the bark of a tree. On the other hand, natural selection drives species with variable backgrounds and habitats to move symmetrical patterns away from the centre of the wing and body, disrupting their predators' symmetry recognition.


Principles

Camouflage can be achieved by different methods. Most of the methods help to hide against a background; but mimesis and motion dazzle protect without hiding. Methods may be applied on their own or in combination. Many mechanisms are visual, but some research has explored the use of techniques against
olfactory The sense of smell, or olfaction, is the special sense through which smells (or odors) are perceived. The sense of smell has many functions, including detecting desirable foods, hazards, and pheromones, and plays a role in taste. In humans, it ...
(scent) and acoustic (sound) detection. Methods may also apply to military equipment.


Background matching

Some animals' colours and patterns match a particular natural background. This is an important component of camouflage in all environments. For instance, tree-dwelling
parakeet A parakeet is any one of many small- to medium-sized species of parrot, in multiple genera, that generally has long tail feathers. Etymology and naming The name ''parakeet'' is derived from the French word ''perroquet'', which is reflect ...
s are mainly green;
woodcock The woodcocks are a group of seven or eight very similar living species of sandpipers in the genus ''Scolopax''. The genus name is Latin for a snipe or woodcock, and until around 1800 was used to refer to a variety of waders. The English name ...
s of the forest floor are brown and speckled; reedbed
bittern Bitterns are birds belonging to the subfamily Botaurinae of the heron family Ardeidae. Bitterns tend to be shorter-necked and more secretive than other members of the family. They were called ''hæferblæte'' and various iterations of ''rared ...
s are streaked brown and buff; in each case the animal's coloration matches the hues of its habitat. Similarly,
desert animals A xerocole (), is a general term referring to any animal that is adapted to live in a desert. The main challenges xerocoles must overcome are lack of water and excessive heat. To conserve water they avoid evaporation and concentrate excretions (i. ...
are almost all desert coloured in tones of sand, buff, ochre, and brownish grey, whether they are mammals like the
gerbil The Mongolian gerbil or Mongolian jird (''Meriones unguiculatus'') is a rodent belonging to the subfamily Gerbillinae. Their body size is typically , with a tail, and body weight , with adult males larger than females. The animal is used in s ...
or
fennec fox The fennec fox (''Vulpes zerda'') is a small fox native to the deserts of North Africa, ranging from Western Sahara and Mauritania to the Sinai Peninsula. Its most distinctive feature is its unusually large ears, which serve to dissipate hea ...
, birds such as the
desert lark The desert lark (''Ammomanes deserti'') breeds in deserts and semi-deserts from Morocco to western India. It has a very wide distribution and faces no obvious threats, and surveys have shown that it is slowly increasing in numbers as it expands ...
or
sandgrouse Sandgrouse is the common name for Pteroclidae (), a family (biology), family of sixteen species of bird, members of the order Pterocliformes (). They are traditionally placed in two Genus, genera. The two central Asian species are classified as ...
, or reptiles like the
skink Skinks are a type of lizard belonging to the family (biology), family Scincidae, a family in the Taxonomic rank, infraorder Scincomorpha. With more than 1,500 described species across 100 different taxonomic genera, the family Scincidae is one o ...
or horned viper. Military uniforms, too, generally resemble their backgrounds; for example
khaki The color khaki (, ) is a light shade of tan (color), tan with a slight yellowish tinge. Khaki has been used by many armies around the world for uniforms and equipment, particularly in arid or desert regions, where it provides camouflage rela ...
uniforms are a muddy or dusty colour, originally chosen for service in South Asia. Many moths show
industrial melanism Industrial melanism is an evolutionary effect prominent in several arthropods, where dark pigmentation (melanism) has evolved in an environment affected by industrial pollution, including Sulfur dioxide, sulphur dioxide gas and dark soot deposit ...
, including the
peppered moth The peppered moth (''Biston betularia'') is a temperate species of Nocturnality, night-flying moth. It is mostly found in the northern hemisphere in places like Asia, Europe and North America. Peppered moth evolution is an example of populatio ...
which has coloration that blends in with tree bark. The coloration of these insects evolved between 1860 and 1940 to match the changing colour of the tree trunks on which they rest, from pale and mottled to almost black in polluted areas. This is taken by zoologists as evidence that camouflage is influenced by natural selection, as well as demonstrating that it changes where necessary to resemble the local background. File:Lion-in-tall-grass.jpg, Lion in Kruger National Park, South Africa, blending in with the tall grass File:Tanzania 0607 cropped Nevit.jpg, Black-faced sandgrouse is coloured like its desert background. File:Caprimulgus aegyptius.jpg, Egyptian nightjar nests in open sand with only its camouflaged plumage to protect it. File:Katydid camouflaged in basil plant.jpg, Bright green
katydid Insects in the family Tettigoniidae are commonly called katydids (especially in North America) or bush crickets. They have previously been known as "long-horned grasshoppers". More than 8,000 species are known. Part of the suborder Ensifera, the ...
has the colour of fresh vegetation.


Disruptive coloration

Disruptive patterns use strongly contrasting, non-repeating markings such as spots or stripes to break up the outlines of an animal or military vehicle, or to conceal telltale features, especially by masking the eyes, as in the
common frog The common frog or grass frog (''Rana temporaria''), also known as the European common frog, European common brown frog, European grass frog, European Holarctic true frog, European pond frog or European brown frog or simply the frog, is a semi ...
. Disruptive patterns may use more than one method to defeat visual systems such as
edge detection Edge or EDGE may refer to: Technology Computing * Edge computing, a network load-balancing system * Edge device, an entry point to a computer network * Adobe Edge, a graphical development application * Microsoft Edge, a web browser developed b ...
. Predators like the
leopard The leopard (''Panthera pardus'') is one of the five extant cat species in the genus ''Panthera''. It has a pale yellowish to dark golden fur with dark spots grouped in rosettes. Its body is slender and muscular reaching a length of with a ...
use disruptive camouflage to help them approach prey, while potential prey use it to avoid detection by predators. Disruptive patterning is 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 factors like shape, shine, and shadow. The presence of bold skin markings does not in itself prove that an animal relies on camouflage, as that depends on its behaviour. Roosevelt attacks Thayer on page 191, arguing that neither zebra nor giraffe are "'adequately obliterated' by countershading or coloration pattern or anything else." For example, although
giraffe The giraffe is a large Fauna of Africa, African even-toed ungulate, hoofed mammal belonging to the genus ''Giraffa.'' It is the Largest mammals#Even-toed Ungulates (Artiodactyla), tallest living terrestrial animal and the largest ruminant on ...
s have a high contrast pattern that could be disruptive coloration, the adults are very conspicuous when in the open. Some authors have argued that adult giraffes are cryptic, since when standing among trees and bushes they are hard to see at even a few metres' distance. However, adult giraffes move about to gain the best view of an approaching predator, relying on their size and ability to defend themselves, even from lions, rather than on camouflage. A different explanation is implied by young giraffes being far more vulnerable to predation than adults. More than half of all giraffe calves die within a year, and giraffe mothers hide their newly born calves, which spend much of the time lying down in cover while their mothers are away feeding. The mothers return once a day to feed their calves with milk. Since the presence of a mother nearby does not affect survival, it is argued that these juvenile giraffes must be very well camouflaged; this is supported by coat markings being strongly inherited. The possibility of
camouflage in plants In evolutionary biology, mimicry in plants is where a plant evolves to resemble another organism physically or chemically. Mimicry in plants has been studied far less than mimicry in animals. It may provide protection against herbivory, or may ...
was little studied until the late 20th century. Leaf
variegation '' Cryptocarya williwilliana'' showing leaf venation and variegated leaves Variegation is the appearance of differently coloured zones in the foliage, flowers, and sometimes the stems and fruit of plants, granting a speckled, striped, or patch ...
with white spots may serve as camouflage in forest
understory In forestry and ecology, understory (American English), or understorey (English in the Commonwealth of Nations, Commonwealth English), also known as underbrush or undergrowth, includes plant life growing beneath the Canopy (biology), forest ca ...
plants, where there is a dappled background; leaf mottling is correlated with closed habitats. Disruptive camouflage would have a clear evolutionary advantage in plants: they would tend to escape from being eaten by
herbivore A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat ...
s. Another possibility is that some plants have leaves differently coloured on upper and lower surfaces or on parts such as veins and stalks to make green-camouflaged insects conspicuous, and thus benefit the plants by favouring the removal of herbivores by carnivores. These hypotheses are testable. File:Great male Leopard in South Afrika-JD.JPG, Leopard: a disruptively camouflaged predator File:T-90 main battle tank (2).jpg, Russian T-90 battle tank painted in bold disruptive pattern of sand and green File:Gaboon viper (4530693343).jpg,
Gaboon viper The Gaboon viper (''Bitis gabonica''), also called the Gaboon adder, is a large and highly venomous viper species found in the rainforests and savannas of sub-Saharan Africa.McDiarmid RW, Campbell JA, Touré T. 1999. ''Snake Species of the Wor ...
's bold markings are powerfully disruptive. File:Ptarmigan and five chicks.JPG, A
ptarmigan ''Lagopus'' is a genus of birds in the grouse subfamily commonly known as ptarmigans (). The genus contains four living species with numerous described subspecies, all living in tundra or cold upland areas. Taxonomy and etymology The genus ''L ...
and five chicks exhibit exceptional disruptive camouflage File:Jumping spider with prey.jpg,
Jumping spider Jumping spiders are a group of spiders that constitute the family (biology), family Salticidae. , this family contained over 600 species description, described genus, genera and over 6,000 described species, making it the largest family of spide ...
: a disruptively camouflaged invertebrate predator File:Smilax bona-nox, Colt Creek State Park, Lakeland, Florida.jpg, Many
understory In forestry and ecology, understory (American English), or understorey (English in the Commonwealth of Nations, Commonwealth English), also known as underbrush or undergrowth, includes plant life growing beneath the Canopy (biology), forest ca ...
plants such as the saw greenbriar, ''
Smilax bona-nox ''Smilax bona-nox'', the saw greenbrier, is a species of plant in the family Smilacaceae. It is native to the Southern United States, and eastern Mexico. Description ''Smilax bona-nox,'' also known as saw greenbrier, is a flowering vine that ...
'' have pale markings, possibly disruptive camouflage.


Countershading

Countershading uses graded colour to counteract the effect of self-shadowing, creating an illusion of flatness. Self-shadowing makes an animal appear darker below than on top, grading from light to dark; countershading 'paints in' tones which are darkest on top, lightest below, making the countershaded animal nearly invisible against a suitable background. Thayer observed that "Animals are painted by Nature, darkest on those parts which tend to be most lighted by the sky's light, and ''vice versa''". Accordingly, the principle of countershading is sometimes called Thayer's Law. Countershading is widely used by
terrestrial animals Terrestrial animals are animals that live predominantly or entirely on land (e.g. cats, chickens, ants, most spiders), as compared with aquatic animals, which live predominantly or entirely in the water (e.g. fish, lobsters, octopuses), and se ...
, such as
gazelle A gazelle is one of many antelope species in the genus ''Gazella'' . There are also seven species included in two further genera; '' Eudorcas'' and '' Nanger'', which were formerly considered subgenera of ''Gazella''. A third former subgenus, ' ...
s and grasshoppers; marine animals, such as
sharks Sharks are a group of elasmobranch cartilaginous fish characterized by a ribless endoskeleton, dermal denticles, five to seven gill slits on each side, and pectoral fins that are not fused to the head. Modern sharks are classified within the ...
and
dolphins A dolphin is an aquatic mammal in the cetacean clade Odontoceti (toothed whale). Dolphins belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontopori ...
; and birds, such as
snipe A snipe is any of about 26 wading bird species in three genera in the family Scolopacidae. They are characterized by a very long, slender bill, eyes placed high on the head, and cryptic/ camouflaging plumage. ''Gallinago'' snipe have a nearly ...
and
dunlin The dunlin (''Calidris alpina'') is a small wader in the genus '' Calidris''. The English name is a dialect form of "dunling", first recorded in 1531–1532. It derives from ''dun'', "dull brown", with the suffix ''-ling'', meaning a person or ...
. Countershading is less often used for military camouflage, despite Second World War experiments that showed its effectiveness. English zoologist
Hugh Cott Hugh Bamford Cott (6 July 1900 – 18 April 1987) was a British zoologist, an authority on both natural and military camouflage, and a scientific illustrator and photographer. Many of his field studies took place in Africa, where he was especia ...
encouraged the use of methods including countershading, but despite his authority on the subject, failed to persuade the British authorities. Soldiers often wrongly viewed camouflage netting as a kind of invisibility cloak, and they had to be taught to look at camouflage practically, from an enemy observer's viewpoint. At the same time in
Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...
, zoologist William John Dakin advised soldiers to copy animals' methods, using their instincts for wartime camouflage. The term countershading has a second meaning unrelated to Thayer's Law. It is that the upper and undersides of animals such as sharks, and of some military aircraft, are different colours to match the different backgrounds when seen from above or from below. Here the camouflage consists of two surfaces, each with the simple function of providing concealment against a specific background, such as a bright water surface or the sky. The body of a shark or the
fuselage The fuselage (; from the French language, French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds Aircrew, crew, passengers, or cargo. In single-engine aircraft, it will usually contain an Aircraft engine, engine as wel ...
of an aircraft is not gradated from light to dark to appear flat when seen from the side. The camouflage methods used are the matching of background colour and pattern, and disruption of outlines. File:Gazella-dorcas.jpg, Countershaded
Dorcas gazelle The dorcas gazelle (''Gazella dorcas''), also known as the ariel gazelle, is a small and common gazelle. The dorcas gazelle stands about at the shoulder, with a head and body length of and a weight of . The numerous subspecies survive on veget ...
, ''Gazella dorcas'' File:Tiburón.jpg, Countershaded
grey reef shark The grey reef shark or gray reef shark (''Carcharhinus amblyrhynchos'', sometimes misspelled ''amblyrhynchus'' or ''amblyrhinchos'') is a species of requiem shark, in the family (biology), family Requiem shark, Carcharhinidae. One of the most com ...
, ''Carcharhinus amblyrhynchos'' File:Thayers ships.jpg, Countershaded ship and submarine in Thayer's 1902 patent application File:Abbott thayer countershading.jpg, Two model birds painted by Thayer: painted in background colours on the left, countershaded and nearly invisible on the right File:Focke-Wulf Fw 190D-9 outside USAF.jpg, Countershaded Focke-Wulf Fw 190D-9


Eliminating shadow

Some animals, such as the
horned lizard ''Phrynosoma'', whose members are known as the horned lizards, horny toads, or horntoads, is a genus of North American lizards and the type genus of the Family (biology), family Phrynosomatidae. Their common names refer directly to their horns or ...
s 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 effectively hide and disrupt any remaining areas of shadow there may be under the edge of the body. The theory that the body shape of the horned lizards which live in open desert is adapted to minimise shadow is supported by the one species which lacks fringe scales, the roundtail horned lizard, which lives in rocky areas and resembles a rock. When this species is threatened, it makes itself look as much like a rock as possible by curving its back, emphasizing its three-dimensional shape. Some species of butterflies, such as the speckled wood, ''
Pararge aegeria The speckled wood (''Pararge aegeria'') is a butterfly found in and on the borders of woodland areas throughout much of the Palearctic realm. The species is subdivided into multiple subspecies, including ''Pararge aegeria aegeria'', ''Pararge aeg ...
'', minimise their shadows when perched by closing the wings over their backs, aligning their bodies with the sun, and tilting to one side towards the sun, so that the shadow becomes a thin inconspicuous line rather than a broad patch. Similarly, some ground-nesting birds, including the
European nightjar The European nightjar (''Caprimulgus europaeus''), common goatsucker, Eurasian nightjar or just nightjar is a crepuscular and nocturnal bird in the nightjar family that breeds across most of Europe and the Palearctic to Mongolia and Northweste ...
, select a resting position facing the sun. Eliminating shadow was identified as a principle of military camouflage during the
Second World War World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
. File:Ibexes.jpg, Three countershaded and cryptically coloured
ibex An ibex ( : ibex, ibexes or ibices) is any of several species of wild goat (genus ''Capra''), distinguished by the male's large recurved horns, which are transversely ridged in front. Ibex are found in Eurasia, North Africa and East Africa. T ...
almost invisible in the Israeli desert File:Armoured personnel carriers, Eriboll - geograph.org.uk - 1316295.jpg, "Shape, shine, shadow" make these 'camouflaged' military vehicles easily visible. File:Phrynosoma mcallii.jpg, The
flat-tail horned lizard The flat-tail horned lizard (''Phrynosoma mcallii'') is a species of lizard in the family Phrynosomatidae. A species of reptile, it is endemic to the Sonoran Desert of the southwestern United States and northwestern Mexico. Its multiple adaptatio ...
's body is flattened and fringed to minimise its shadow. File:Øvelse på Evjemoen Tropp 4.2 - camouflage nettings.jpg, Camouflage
netting In law, set-off or netting is a legal technique applied between persons or businesses with mutual rights and Liability (financial accounting), liabilities, replacing gross positions with net positions. It permits the rights to be used to discharg ...
is draped away from a military vehicle to reduce its shadow. File:Perfect Camouflage (Caterpillar on teakwood branch).jpg, A caterpillar's fringe of bristles conceals its shadow.


Distraction

Many prey animals have conspicuous high-contrast markings which paradoxically attract the predator's gaze. These distractive markings may serve as camouflage by distracting the predator's attention from recognising the prey as a whole, for example by keeping the predator from identifying the prey's outline. Experimentally, search times for
blue tit The Eurasian blue tit (''Cyanistes caeruleus'') is a small passerine bird in the tit (bird), tit family, Paridae. It is easily recognizable by its blue and yellow plumage and small size. Eurasian blue tits, usually resident bird, resident a ...
s increased when artificial prey had distractive markings.


Cryptic behaviour

Movement catches the eye of prey animals on the lookout for predators, and of predators hunting for prey. Most methods of crypsis therefore also require suitable cryptic behaviour, such as lying down and keeping still to avoid being detected, or in the case of stalking predators such as the
tiger The tiger (''Panthera tigris'') is a large Felidae, cat and a member of the genus ''Panthera'' native to Asia. It has a powerful, muscular body with a large head and paws, a long tail and orange fur with black, mostly vertical stripes. It is ...
, moving with extreme stealth, both slowly and quietly, watching its prey for any sign they are aware of its presence. As an example of the combination of behaviours and other methods of crypsis involved, young giraffes seek cover, lie down, and keep still, often for hours until their mothers return; their skin pattern blends with the pattern of the vegetation, while the chosen cover and lying position together hide the animals' shadows. The
flat-tail horned lizard The flat-tail horned lizard (''Phrynosoma mcallii'') is a species of lizard in the family Phrynosomatidae. A species of reptile, it is endemic to the Sonoran Desert of the southwestern United States and northwestern Mexico. Its multiple adaptatio ...
similarly relies on a combination of methods: it is adapted to lie flat in the open desert, relying on stillness, its cryptic coloration, and concealment of its shadow to avoid being noticed by predators. In the ocean, the leafy sea dragon sways mimetically, like the seaweeds amongst which it rests, as if rippled by wind or water currents. Swaying is seen also in some insects, like Macleay's spectre stick insect, '' Extatosoma tiaratum''. The behaviour may be motion crypsis, preventing detection, or motion masquerade, promoting misclassification (as something other than prey), or a combination of the two.


Motion camouflage

Most forms of camouflage are ineffective when the camouflaged animal or object moves, because the motion is easily seen by the observing predator, prey or enemy. However, insects such as
hoverflies Hoverflies, also called flower flies or syrphids, make up the insect family (biology), family Syrphidae. As their common name suggests, they are often seen Hover (behaviour), hovering or nectaring at flowers; the adults of many species feed main ...
and
dragonflies A dragonfly is a flying insect belonging to the infraorder Anisoptera below the order Odonata. About 3,000 extant species of dragonflies are known. Most are tropical, with fewer species in temperate regions. Loss of wetland habitat threate ...
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. Some insects sway while moving to appear to be blown by the wind. The same method can be used for military purposes, for example by missiles to minimise their risk of detection by an enemy. However, missile engineers, and animals such as bats, use the method mainly for its efficiency rather than camouflage. File:Hoverfly August 2007-8.jpg, Male ''
Syritta pipiens ''Syritta pipiens'', sometimes called the thick-legged hoverfly, is one of the most common species in the insect family Syrphidae. This fly originates from Europe and is currently distributed across Palearctic, Eurasia and North America. They ar ...
'' hoverflies use motion camouflage to approach females File:Australian Emperor mating and laying.jpg, Male Australian Emperor dragonflies use motion camouflage to approach rivals. File:Motion Camouflage.webm, thumbtime=2, Preying mantises exhibiting motion camouflage.


Mimesis

In
mimesis Mimesis (; , ''mīmēsis'') is a term used in literary criticism and philosophy that carries a wide range of meanings, including '' imitatio'', imitation, similarity, receptivity, representation, mimicry, the act of expression, the act of ...
(also called ''masquerade''), the camouflaged object looks like something else which is of no special interest to the observer. Mimesis is common in prey animals, for example when a
peppered moth The peppered moth (''Biston betularia'') is a temperate species of Nocturnality, night-flying moth. It is mostly found in the northern hemisphere in places like Asia, Europe and North America. Peppered moth evolution is an example of populatio ...
caterpillar mimics a twig, or a grasshopper mimics a dry leaf. It is also found in nest structures; some eusocial wasps, such as ''
Leipomeles dorsata ''Leipomeles dorsata ''is a neotropical paper wasp that is found across Central America and northern South America. It is a eusocial wasp with little differentiation between reproducing and non-reproducing females. In fact, workers can become tem ...
'', build a nest envelope in patterns that mimic the leaves surrounding the nest. Mimesis is also employed by some
predators Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill ...
and
parasite Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted str ...
s to lure their prey. For example, a
flower mantis Flower mantises are praying mantises that use a special form of camouflage referred to as aggressive mimicry, which they not only use to attract prey, but avoid predators as well. These insects have specific colorations and behaviors that mimic ...
mimics a particular kind of flower, such as an
orchid Orchids are plants that belong to the family Orchidaceae (), a diverse and widespread group of flowering plants with blooms that are often colourful and fragrant. Orchids are cosmopolitan plants that are found in almost every habitat on Eart ...
. This tactic has occasionally been used in warfare, for example with heavily armed
Q-ship Q-ships, also known as Q-boats, decoy vessels, special service ships, or mystery ships, were heavily armed merchantman, armed merchant ships with concealed weaponry, designed to lure submarines into making surface attacks. This gave Q-ships the c ...
s disguised as merchant ships. The
common cuckoo The cuckoo, common cuckoo, European cuckoo or Eurasian cuckoo (''Cuculus canorus'') is a member of the cuckoo order of birds, Cuculiformes, which includes the Geococcyx, roadrunners, the ani (bird), anis and the coucals. This species is a widesp ...
, a
brood parasite Brood may refer to: Nature * Brood, a collective term for offspring * Brooding, the incubation of bird eggs by their parents * Bee brood, the young of a beehive * Individual broods of North American periodical cicadas: ** Brood X, the largest ...
, provides examples of mimesis both in the adult and in the egg. The female lays her eggs in nests of other, smaller species of bird, one per nest. The female mimics a
sparrowhawk Sparrowhawk (sometimes sparrow hawk) may refer to several species of small hawk in the subfamily Accipitrinae The Accipitrinae are the Family (biology), subfamily of the Accipitridae often known as the "true" hawks. The subfamily contains 73 s ...
. The resemblance is sufficient to make small birds take action to avoid the apparent predator. The female cuckoo then has time to lay her egg in their nest without being seen to do so. The cuckoo's egg mimics the eggs of the host species, reducing its chance of being rejected. File:Biston betularia.png,
Peppered moth The peppered moth (''Biston betularia'') is a temperate species of Nocturnality, night-flying moth. It is mostly found in the northern hemisphere in places like Asia, Europe and North America. Peppered moth evolution is an example of populatio ...
caterpillars mimic twigs File:Insect camouflage PP08338.png,
Flower mantis Flower mantises are praying mantises that use a special form of camouflage referred to as aggressive mimicry, which they not only use to attract prey, but avoid predators as well. These insects have specific colorations and behaviors that mimic ...
lures its insect prey by mimicking a ''
Phalaenopsis ''Phalaenopsis'' (), also known as moth orchids, is a genus of about seventy species of plants in the family Orchidaceae. Orchids in this genus are monopodial epiphytes or lithophytes with long, coarse roots, short, leafy stems and long-lastin ...
'' orchid blossom File:Hooded Grasshopper (Teratodus monticollis) W IMG 0525.jpg, Hooded grasshopper ''Teratodus monticollis'', superbly mimics a leaf with a bright orange border File:Gumleaf grasshopper.jpg, This
grasshopper Grasshoppers are a group of insects belonging to the suborder Caelifera. They are amongst what are possibly the most ancient living groups of chewing herbivorous insects, dating back to the early Triassic around 250 million years ago. Grassh ...
hides from predators by mimicking a dry leaf File:IWM-E-18461-Crusader-camouflaged-19421026.jpg, WWII
tank A tank is an armoured fighting vehicle intended as a primary offensive weapon in front-line ground combat. Tank designs are a balance of heavy firepower, strong armour, and battlefield mobility provided by tracks and a powerful engine; ...
concealed in
Operation Bertram Operation Bertram was a Second World War military deception, deception operation practised by the Allied forces in Egypt led by Bernard Montgomery, in the months before the Second Battle of El Alamein in 1942. Bertram was devised by Dudley Clark ...
by mimicking a truck File:HMS President - geograph.org.uk - 659583.jpg, Armed WW1
Q-ship Q-ships, also known as Q-boats, decoy vessels, special service ships, or mystery ships, were heavily armed merchantman, armed merchant ships with concealed weaponry, designed to lure submarines into making surface attacks. This gave Q-ships the c ...
lured enemy submarines by mimicking a
merchantman A merchant ship, merchant vessel, trading vessel, or merchantman is a watercraft that transports cargo or carries passengers for hire. This is in contrast to pleasure craft, which are used for personal recreation, and naval ships, which are us ...
File:European Cuckoo Mimics Sparrowhawk.jpg,
Cuckoo Cuckoos are birds in the Cuculidae ( ) family, the sole taxon in the order Cuculiformes ( ). The cuckoo family includes the common or European cuckoo, roadrunners, koels, malkohas, couas, coucals, and anis. The coucals and anis are somet ...
adult mimics
sparrowhawk Sparrowhawk (sometimes sparrow hawk) may refer to several species of small hawk in the subfamily Accipitrinae The Accipitrinae are the Family (biology), subfamily of the Accipitridae often known as the "true" hawks. The subfamily contains 73 s ...
, giving female time to lay eggs parasitically File:Cuckoo Eggs Mimicking Reed Warbler Eggs.JPG, Cuckoo eggs mimicking smaller eggs, in this case of
reed warbler The ''Acrocephalus'' warblers are small, insectivorous passerine birds belonging to the genus ''Acrocephalus''. Formerly in the paraphyletic Old World warbler assemblage, they are now separated as the namesake of the marsh and tree warbler famil ...
File:Wrap-around spider in the genus Dolophones (Family Araneidae) Camouflage View.JPG, Wrap-around spider ''Dolophones'' mimicking a stick


Motion dazzle

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 method, motion dazzle, requires rapidly moving bold patterns of contrasting stripes. 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). As of 2011, motion dazzle had been proposed for military vehicles, but never applied. Since motion dazzle patterns would make animals more difficult to locate accurately when moving, but easier to see when stationary, there would be an evolutionary trade-off between motion dazzle and crypsis. An animal that is commonly thought to be dazzle-patterned is the
zebra Zebras (, ) (subgenus ''Hippotigris'') are African equines with distinctive black-and-white striped coats. There are three living species: Grévy's zebra (''Equus grevyi''), the plains zebra (''E. quagga''), and the mountain zebra (''E. ...
. The bold stripes of the zebra have been claimed to be disruptive camouflage, background-blending and countershading. After many years in which the purpose of the coloration was disputed, an experimental study by
Tim Caro Timothy M. Caro (born 1951) is a British evolutionary ecologist known for his work on conservation biology, animal behaviour, anti-predator defences in animals, and the function of zebra stripes. He is the author of several textbooks on these su ...
suggested in 2012 that the pattern reduces the attractiveness of stationary models to biting flies such as horseflies and
tsetse flies Tsetse ( , or ) (sometimes spelled tzetze; also known as tik-tik flies) are large, biting flies that inhabit much of tropical Africa. Tsetse flies include all the species in the genus ''Glossina'', which are placed in their own family, Glos ...
. However, a simulation study by Martin How and Johannes Zanker in 2014 suggests that when moving, the stripes may confuse observers, such as mammalian predators and biting insects, by two
visual illusion In visual perception, an optical illusion (also called a visual illusion) is an illusion caused by the visual system and characterized by a visual perception, percept that arguably appears to differ from reality. Illusions come in a wide varie ...
s: the
wagon-wheel effect The wagon-wheel effect (alternatively called stagecoach-wheel effect) is an optical illusion in which a spoked wheel appears to rotate differently from its true rotation. The wheel can appear to rotate more slowly than the true rotation, it ca ...
, where the perceived motion is inverted, and the
barberpole illusion The barberpole illusion is a visual illusion that reveals biases in the processing of visual motion in the human brain. This visual illusion occurs when a diagonally striped pole is rotated around its vertical axis (horizontally), it appears as t ...
, where the perceived motion is in a wrong direction.


Mechanisms

Animals can camouflage themselves by one or more principles using a variety of mechanisms. For example, some animals achieve background matching by changing their skin coloration to resemble their current background.


Changeable skin coloration

Animals such as
chameleon Chameleons or chamaeleons (Family (biology), family Chamaeleonidae) are a distinctive and highly specialized clade of Old World lizards with 200 species described as of June 2015. The members of this Family (biology), family are best known for ...
, frog, flatfish such as the peacock flounder, squid, octopus and even the isopod
idotea balthica ''Idotea balthica'' is a species of marine isopod which lives on seaweed and seagrass in the subtidal zone of rocky shores and sandy lagoons. Distribution ''Idotea balthica'' has a broad geographical distribution, having been recorded from the ...
actively change their skin patterns and colours using special
chromatophore Chromatophores are cells that produce color, of which many types are pigment-containing cells, or groups of cells, found in a wide range of animals including amphibians, fish, reptiles, crustaceans and cephalopod A cephalopod is any member o ...
cells to resemble their current background, or, as in most chameleons, for
signalling A signal is both the process and the result of transmission of data over some media accomplished by embedding some variation. Signals are important in multiple subject fields including signal processing, information theory and biology. In ...
. However, Smith's dwarf chameleon does use active colour change for camouflage. Each chromatophore contains pigment of only one colour. In fish and frogs, colour change is mediated by a type of chromatophore known as
melanophore Chromatophores are cells that produce color, of which many types are pigment-containing cells, or groups of cells, found in a wide range of animals including amphibians, fish, reptiles, crustaceans and cephalopods. Mammals and birds, in contrast ...
s that contain dark pigment. A melanophore is star-shaped; it contains many small pigmented
organelle In cell biology, an organelle is a specialized subunit, usually within a cell (biology), cell, that has a specific function. The name ''organelle'' comes from the idea that these structures are parts of cells, as Organ (anatomy), organs are to th ...
s which can be dispersed throughout the cell, or aggregated near its centre. When the pigmented organelles are dispersed, the cell makes a patch of the animal's skin appear dark; when they are aggregated, most of the cell, and the animal's skin, appears light. In frogs, the change is controlled relatively slowly, mainly by
hormone A hormone (from the Ancient Greek, Greek participle , "setting in motion") is a class of cell signaling, signaling molecules in multicellular organisms that are sent to distant organs or tissues by complex biological processes to regulate physio ...
s. In fish, the change is controlled by the brain, which sends signals directly to the chromatophores, as well as producing hormones. The skins of cephalopods such as the octopus contain complex units, each consisting of a chromatophore with surrounding muscle and nerve cells. The cephalopod chromatophore has all its pigment grains in a small elastic sac, which can be stretched or allowed to relax under the control of the brain to vary its opacity. By controlling chromatophores of different colours, cephalopods can rapidly change their skin patterns and colours. On a longer timescale, animals like the
Arctic hare The Arctic hare (''Lepus arcticus'') is a species of hare highly adapted to living in the Arctic tundra and other icy biomes. The Arctic hare survives with shortened ears and limbs, a small nose, fat that makes up close to 20% of its body, and a ...
,
Arctic fox The Arctic fox (''Vulpes lagopus''), also known as the white fox, polar fox, or snow fox, is a small species of fox native to the Arctic regions of the Northern Hemisphere and common throughout the Tundra#Arctic tundra, Arctic tundra biome. I ...
,
stoat The stoat (''Mustela erminea''), also known as the Eurasian ermine or ermine, is a species of mustelid native to Eurasia and the northern regions of North America. Because of its wide circumpolar distribution, it is listed as Least Concern on th ...
, and
rock ptarmigan The rock ptarmigan (''Lagopus muta'') is a medium-sized game bird in the grouse family. It is known simply as the ptarmigan in Europe. It is the official bird for the Canadian territory of Nunavut, where it is known as the ''aqiggiq'' (ᐊᕿ� ...
have
snow camouflage Snow camouflage is the use of a coloration or pattern for effective camouflage in winter, often combined with a different summer camouflage. Summer patterns are typically disruptively patterned combinations of shades of browns and greys, up to b ...
, changing 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 to do so. However, Arctic hares which live in the far north of
Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...
, where summer is very short, remain white year-round. The principle of varying coloration either rapidly or with the changing seasons has military applications. ''
Active camouflage Active camouflage or adaptive camouflage is camouflage that adapts, often rapidly, to the surroundings of an object such as an animal or military vehicle. In theory, active camouflage could provide perfect concealment from visual detection. Acti ...
'' could in theory make use of both dynamic colour change and counterillumination. Simple methods such as changing uniforms and repainting vehicles for winter have been in use since World War II. In 2011,
BAE Systems BAE Systems plc is a British Multinational corporation, multinational Aerospace industry, aerospace, military technology, military and information security company, based in London. It is the largest manufacturer in Britain as of 2017. It is ...
announced their
Adaptiv Adaptiv is an active camouflage technology developed by BAE Systems AB to protect military vehicles from detection by far infrared night vision devices, providing infrared stealth. It consists of an array of hexagonal Peltier plates which can be ...
infrared camouflage technology. It uses about 1,000 hexagonal panels to cover the sides of a tank. The Peltier plate panels are heated and cooled to match either the vehicle's surroundings (crypsis), or an object such as a car (mimesis), when viewed in infrared. File:Rock Ptarmigan (Lagopus Muta).jpg, Rock ptarmigan, changing colour in springtime. The male is still mostly in winter plumage File:Norwegian Winter War Volunteers.jpg, Norwegian volunteer soldiers in
Winter War The Winter War was a war between the Soviet Union and Finland. It began with a Soviet invasion of Finland on 30 November 1939, three months after the outbreak of World War II, and ended three and a half months later with the Moscow Peac ...
, 1940, with white camouflage overalls over their uniforms File:Arctic Hare.jpg, Arctic hares in the low arctic change from brown to white in winter File:Bundesarchiv Bild 101III-Roth-173-01, Russland, Raum Charkow, Jagdpanzer.jpg, Snow-camouflaged German
Marder III ''Marder'' III was the name for a series of World War II German tank destroyers. They mounted either the modified ex-Soviet 76.2 mm F-22 Model 1936 divisional field gun, or the German 7.5 cm PaK 40, in an open-topped fighting compartment o ...
jagdpanzer ''Jagdpanzer'' ("tank destroyer") (JgPz) is the name given in German to an armored, tracked tank destroyer, although it may also be used for other kinds of self-propelled guns. Translated from German, ''Jagdpanzer'' meaning "hunting tank". I ...
and white-overalled crew and infantry in Russia, 1943 File:Yemen Chameleon (cropped).jpg,
Veiled chameleon The veiled chameleon (''Chamaeleo calyptratus'') is a species of chameleon (family Chamaeleonidae) native to the Arabian Peninsula in Yemen and Saudi Arabia. Other common names include cone-head chameleon, Yemen chameleon, and Yemeni chameleon. ...
, ''Chamaeleo calyptratus'', changes colour mainly in relation to mood and for signalling. File:Adaptiv infrared camouflage demo hiding tank as car.jpg,
Adaptiv Adaptiv is an active camouflage technology developed by BAE Systems AB to protect military vehicles from detection by far infrared night vision devices, providing infrared stealth. It consists of an array of hexagonal Peltier plates which can be ...
infrared camouflage lets an armoured vehicle mimic a car.


Self-decoration

Some animals actively seek to hide by decorating themselves with materials such as twigs, sand, or pieces of shell from their environment, to break up their outlines, to conceal the features of their bodies, and to match their backgrounds. For example, a
caddisfly The caddisflies (order Trichoptera) are a group of insects with aquatic larvae and terrestrial adults. There are approximately 14,500 described species, most of which can be divided into the suborders Integripalpia and Annulipalpia on the basis ...
larva builds a decorated case and lives almost entirely inside it; a decorator crab covers its back with seaweed, sponges, and stones. The
nymph A nymph (; ; sometimes spelled nymphe) is a minor female nature deity in ancient Greek folklore. Distinct from other Greek goddesses, nymphs are generally regarded as personifications of nature; they are typically tied to a specific place, land ...
of the predatory masked bug uses its hind legs and a ' tarsal fan' to decorate its body with sand or dust. There are two layers of bristles (
trichome Trichomes (; ) are fine outgrowths or appendages on plants, algae, lichens, and certain protists. They are of diverse structure and function. Examples are hairs, glandular hairs, scales, and papillae. A covering of any kind of hair on a plant ...
s) over the body. On these, the nymph spreads an inner layer of fine particles and an outer layer of coarser particles. The camouflage may conceal the bug from both predators and prey. Similar principles can be applied for military purposes, for instance when a
sniper A sniper is a military or paramilitary marksman who engages targets from positions of concealment or at distances exceeding the target's detection capabilities. Snipers generally have specialized training and are equipped with telescopic si ...
wears a
ghillie suit A ghillie suit is a type of camouflage clothing designed to resemble the background environmentsuch as foliage. Typically, it is a net or cloth garment covered in loose strips of burlap ( hessian), cloth, twine, or jute sometimes made to lo ...
designed to be further camouflaged by decoration with materials such as tufts of grass from the sniper's immediate environment. Such suits were used as early as 1916, the British army having adopted "coats of motley hue and stripes of paint" for snipers. Cott takes the example of the larva of the
blotched emerald The blotched emerald (''Comibaena bajularia'') is a moth of the family Geometridae. The species was first described by Michael Denis and Ignaz Schiffermüller in 1775. It is found throughout Europe and the Near East. It has a scattered distribut ...
moth, which fixes a screen of fragments of leaves to its specially hooked bristles, to argue that military camouflage uses the same method, pointing out that the "device is ... essentially the same as one widely practised during the Great War for the concealment, not of caterpillars, but of caterpillar-tractors, unbattery positions, observation posts and so forth." File:Hyastenus elatus.jpg, This decorator crab has covered its body with sponges. File:IDF-CombatEngineeringSniper001.jpg, Sniper in a
Ghillie suit A ghillie suit is a type of camouflage clothing designed to resemble the background environmentsuch as foliage. Typically, it is a net or cloth garment covered in loose strips of burlap ( hessian), cloth, twine, or jute sometimes made to lo ...
with plant materials File:Reduvius personatus, Masked Hunter Bug nymph camouflaged with sand grains.JPG, ''
Reduvius personatus ''Reduvius personatus'' or the masked hunter is an insect belonging to the assassin bug (Reduviidae) family. The name is because its Nymph (biology), nymphs camouflage themselves with dust. The masked hunter is a predator of small arthropods, inc ...
'', masked hunter bug nymph, camouflaged with sand grains File:Battle of Lake Khasan-Camouflaged soviet tanks.jpg, Soviet tanks under netting dressed with vegetation, 1938


Transparency

Many marine animals that float near the surface are highly transparent, giving them almost perfect camouflage. However, transparency is difficult for bodies made of materials that have different
refractive indices In optics, the refractive index (or refraction index) of an optical medium is the ratio of the apparent speed of light in the air or vacuum to the speed in the medium. The refractive index determines how much the path of light is bent, or refrac ...
from seawater. Some marine animals such as
jellyfish Jellyfish, also known as sea jellies or simply jellies, are the #Life cycle, medusa-phase of certain gelatinous members of the subphylum Medusozoa, which is a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animal ...
have gelatinous bodies, composed mainly of water; their thick
mesogloea Mesoglea refers to the extracellular matrix found in cnidarians like coral or jellyfish as well as ctenophores that functions as a hydrostatic skeleton. It is related to but distinct from mesohyl, which generally refers to extracellular material f ...
is acellular and highly transparent. This conveniently makes them
buoyant Buoyancy (), or upthrust, is the force exerted by a fluid opposing the weight of a partially or fully immersed object (which may be also be a parcel of fluid). In a column of fluid, pressure increases with depth as a result of the weight of t ...
, but it also makes them large for their muscle mass, so they cannot swim fast, making this form of camouflage a costly trade-off with mobility. Gelatinous
plankton Plankton are the diverse collection of organisms that drift in Hydrosphere, water (or atmosphere, air) but are unable to actively propel themselves against ocean current, currents (or wind). The individual organisms constituting plankton are ca ...
ic animals are between 50 and 90 percent transparent. A transparency of 50 percent is enough to make an animal invisible to a predator such as
cod Cod (: cod) is the common name for the demersal fish genus ''Gadus'', belonging to the family (biology), family Gadidae. Cod is also used as part of the common name for a number of other fish species, and one species that belongs to genus ''Gad ...
at a depth of ; better transparency is required for invisibility in shallower water, where the light is brighter and predators can see better. For example, a cod can see prey that are 98 percent transparent in optimal lighting in shallow water. Therefore, sufficient transparency for camouflage is more easily achieved in deeper waters. Some tissues such as
muscle Muscle is a soft tissue, one of the four basic types of animal tissue. There are three types of muscle tissue in vertebrates: skeletal muscle, cardiac muscle, and smooth muscle. Muscle tissue gives skeletal muscles the ability to muscle contra ...
s can be made transparent, provided either they are very thin or organised as regular layers or fibrils that are small compared to the wavelength of visible light. A familiar example is the transparency of the lens of the vertebrate
eye An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system. In higher organisms, the ey ...
, which is made of the protein
crystallin In anatomy, a crystallin is a water-soluble structural protein found in the lens and the cornea of the eye accounting for the transparency of the structure. It has also been identified in other places such as the heart, and in aggressive breast ...
, and the vertebrate
cornea The cornea is the transparency (optics), transparent front part of the eyeball which covers the Iris (anatomy), iris, pupil, and Anterior chamber of eyeball, anterior chamber. Along with the anterior chamber and Lens (anatomy), lens, the cornea ...
which is made of the protein
collagen Collagen () is the main structural protein in the extracellular matrix of the connective tissues of many animals. It is the most abundant protein in mammals, making up 25% to 35% of protein content. Amino acids are bound together to form a trip ...
. Other structures cannot be made transparent, notably the
retina The retina (; or retinas) is the innermost, photosensitivity, light-sensitive layer of tissue (biology), tissue of the eye of most vertebrates and some Mollusca, molluscs. The optics of the eye create a focus (optics), focused two-dimensional ...
s or equivalent light-absorbing structures of eyes – they must absorb light to be able to function. The
camera A camera is an instrument used to capture and store images and videos, either digitally via an electronic image sensor, or chemically via a light-sensitive material such as photographic film. As a pivotal technology in the fields of photograp ...
-type eye of vertebrates and cephalopods must be completely opaque. Finally, some structures are visible for a reason, such as to lure prey. For example, the
nematocyst A cnidocyte (also known as a cnidoblast) is a type of cell containing a large secretory organelle called a ''cnidocyst'', that can deliver a sting to other organisms as a way to capture prey and defend against predators. A cnidocyte explosively ...
s (stinging cells) of the transparent
siphonophore Siphonophorae (from Ancient Greek σίφων (siphōn), meaning "tube" and -φόρος (-phóros), meaning "bearing") is an order within Hydrozoa, a class of marine organisms within the phylum Cnidaria. According to the World Register of Marine ...
''
Agalma okenii An agalma () is a cult image or votive offering. Agalma may also refer to: * ''Agalma'' (siphonophore), a marine animal genus in the family Agalmatidae *''Agalma'', a synonym of the flowering plant genus '' Heptapleurum'' * ''Agalma'' (journal) ...
'' resemble small
copepod Copepods (; meaning 'oar-feet') are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (living in the water column), some are benthos, benthic (living on the sedimen ...
s. Examples of transparent marine animals include a wide variety of
larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...
e, including
radiata Radiata or Radiates is a historical taxonomic rank that was used to classify animals with Symmetry (biology)#Radial symmetry, radially symmetric body plans. The term Radiata is no longer accepted, as it united several different groupings of anim ...
(coelenterates), siphonophores,
salps A salp (: salps, also known colloquially as “sea grape”) or salpa (: salpae or salpas) is a barrel-shaped, planktonic tunicate in the family Salpidae. The salp moves by contracting its gelatinous body in order to pump water through it; it ...
(floating
tunicate Tunicates are marine invertebrates belonging to the subphylum Tunicata ( ). This grouping is part of the Chordata, a phylum which includes all animals with dorsal nerve cords and notochords (including vertebrates). The subphylum was at one time ...
s), gastropod molluscs,
polychaete Polychaeta () is a paraphyletic class of generally marine Annelid, annelid worms, common name, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called c ...
worms, many shrimplike
crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...
s, and fish; whereas the adults of most of these are opaque and pigmented, resembling the seabed or shores where they live. Adult
comb jellies Ctenophora (; : ctenophore ) is a phylum of marine invertebrates, commonly known as comb jellies, that inhabit sea waters worldwide. They are notable for the groups of cilia they use for swimming (commonly referred to as "combs"), and they are ...
and jellyfish obey the rule, often being mainly transparent. Cott suggests this follows the more general rule that animals resemble their background: in a transparent medium like seawater, that means being transparent. The small Amazon River fish '' Microphilypnus amazonicus'' and the shrimps it associates with, '' Pseudopalaemon gouldingi'', are so transparent as to be "almost invisible"; further, these species appear to select whether to be transparent or more conventionally mottled (disruptively patterned) according to the local background in the environment.


Silvering

Where transparency cannot be achieved, it can be imitated effectively by silvering to make an animal's body highly reflective. At medium depths at sea, light comes from above, so a mirror oriented vertically makes animals such as fish invisible from the side. Most fish in the upper ocean such as
sardine Sardine and pilchard are common names for various species of small, oily forage fish in the herring suborder Clupeoidei. The term "sardine" was first used in English during the early 15th century; a somewhat dubious etymology says it com ...
and
herring Herring are various species of forage fish, belonging to the Order (biology), order Clupeiformes. Herring often move in large Shoaling and schooling, schools around fishing banks and near the coast, found particularly in shallow, temperate wate ...
are camouflaged by silvering. The
marine hatchetfish Marine hatchetfishes or deep-sea hatchetfishes are small deep-sea mesopelagic ray-finned fish of the stomiiform subfamily Sternoptychinae. They should not be confused with the freshwater hatchetfishes, which are not particularly closely relate ...
is extremely flattened laterally, leaving the body just millimetres thick, and the body is so silvery as to resemble
aluminium foil Aluminium foil (or aluminum foil in American English; occasionally called tin foil) is aluminium prepared in thin metal leaves. The foil is pliable and can be readily bent or wrapped around objects. Thin foils are fragile and are sometimes ...
. The mirrors consist of microscopic structures similar to those used to provide
structural coloration Structural coloration in animals, and a few plants, is the production of colour by microscopically structured surfaces fine enough to interfere with visible light instead of Biological pigment, pigments, although some structural coloration occu ...
: stacks of between 5 and 10 crystals of
guanine Guanine () (symbol G or Gua) is one of the four main nucleotide bases found in the nucleic acids DNA and RNA, the others being adenine, cytosine, and thymine ( uracil in RNA). In DNA, guanine is paired with cytosine. The guanine nucleoside ...
spaced about of a wavelength apart to interfere constructively and achieve nearly 100 per cent reflection. In the deep waters that the hatchetfish lives in, only blue light with a wavelength of 500 nanometres percolates down and needs to be reflected, so mirrors 125 nanometres apart provide good camouflage. In fish such as the herring which live in shallower water, the mirrors must reflect a mixture of wavelengths, and the fish accordingly has crystal stacks with a range of different spacings. A further complication for fish with bodies that are rounded in cross-section is that the mirrors would be ineffective if laid flat on the skin, as they would fail to reflect horizontally. The overall mirror effect is achieved with many small reflectors, all oriented vertically. Silvering is found in other marine animals as well as fish. The
cephalopods A cephalopod is any member of the molluscan Taxonomic rank, class Cephalopoda (Greek language, Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral symm ...
, including squid, octopus and cuttlefish, have multilayer mirrors made of protein rather than guanine.


Counter-illumination

Counter-illumination means producing light to match a background that is brighter than an animal's body or military vehicle; it is a form of active camouflage. It is notably used by some species of
squid A squid (: squid) is a mollusc with an elongated soft body, large eyes, eight cephalopod limb, arms, and two tentacles in the orders Myopsida, Oegopsida, and Bathyteuthida (though many other molluscs within the broader Neocoleoidea are also ...
, such as the
firefly squid The firefly squid (''Watasenia scintillans''), also commonly known as the sparkling enope squid or hotaru-ika in Japan, is a species of squid A squid (: squid) is a mollusc with an elongated soft body, large eyes, eight cephalopod limb, a ...
and the midwater squid. The latter has light-producing organs (
photophores A photophore is a specialized anatomical structure found in a variety of organisms that emits light through the process of Bioluminescence, boluminescence. This light may be produced endogenously by the organism itself (symbiotic) or generat ...
) 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 camouflage is the likely function of the
bioluminescence Bioluminescence is the emission of light during a chemiluminescence reaction by living organisms. Bioluminescence occurs in multifarious organisms ranging from marine vertebrates and invertebrates, as well as in some Fungus, fungi, microorgani ...
of many marine organisms, though light is also produced to attract or to detect prey and for signalling. Counterillumination has rarely been used for military purposes. "
Diffused lighting camouflage Diffused lighting camouflage was a form of active camouflage using counter-illumination to enable Ship camouflage, a ship to match its background, the night sky, that was tested by the Royal Canadian Navy on corvettes during World War II. The pr ...
" was trialled by Canada's National Research Council during the Second World War. It involved projecting light on to the sides of ships to match the faint glow of the night sky, requiring awkward external platforms to support the lamps. The Canadian concept was refined in the American
Yehudi lights Yehudi lights are lamp (electrical component), lamps of automatically controlled brightness placed on the front and leading edges of an aircraft to raise the aircraft's luminance to the average brightness of the sky, a form of active camouflage ...
project, and trialled in aircraft including
B-24 Liberators The Consolidated B-24 Liberator is an American heavy bomber, designed by Consolidated Aircraft of San Diego, California. It was known within the company as the Model 32, and some initial production aircraft were laid down as export models desi ...
and naval
Avengers Avenger(s) or The Avenger(s) may refer to: Arts, entertainment, and media Marvel Comics universe * Avengers (comics), a team of superheroes **Avengers (Marvel Cinematic Universe), a central team of protagonist superheroes of "The Infinity Sag ...
. The planes were fitted with forward-pointing lamps automatically adjusted to match the brightness of the night sky. This enabled them to approach much closer to a target – within – before being seen. Counterillumination was made obsolete by
radar Radar is a system that uses radio waves to determine the distance ('' ranging''), direction ( azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method used to detect and track ...
, and neither diffused lighting camouflage nor Yehudi lights entered active service. File:HMS Largs by night with incomplete Diffused Lighting Camouflage 1942.jpg, HMS ''Largs'' by night with incomplete
diffused lighting camouflage Diffused lighting camouflage was a form of active camouflage using counter-illumination to enable Ship camouflage, a ship to match its background, the night sky, that was tested by the Royal Canadian Navy on corvettes during World War II. The pr ...
, 1942, set to maximum brightness File:HMS Largs bulwark with Diffused Lighting Camouflage fittings.jpg, Bulwark of HMS ''Largs'' showing 4 (of about 60) diffused lighting fittings, 2 lifted, 2 deployed File:Principle of Yehudi Lights with Avenger head-on view.jpg,
Yehudi Lights Yehudi lights are lamp (electrical component), lamps of automatically controlled brightness placed on the front and leading edges of an aircraft to raise the aircraft's luminance to the average brightness of the sky, a form of active camouflage ...
raise the average brightness of the plane from a dark shape to the same as the sky.


Ultra-blackness

Some deep sea fishes have very black skin, reflecting under 0.5% of ambient light. This can prevent detection by predators or prey fish which use bioluminescence for illumination. ''
Oneirodes ''Oneirodes'' is a genus of is a genus of marine ray-finned fish belonging to the family Oneirodidae, the dreamers, a family of deep sea anglerfishes. These predatory, deep-sea fishes are found around the world. This is the type genus, and the m ...
'' had a particularly black skin which reflected only 0.044% of 480 nm wavelength light. The ultra-blackness is achieved with a thin but continuous layer of particles in the
dermis The dermis or corium is a layer of skin between the epidermis (skin), epidermis (with which it makes up the cutis (anatomy), cutis) and subcutaneous tissues, that primarily consists of dense irregular connective tissue and cushions the body from s ...
,
melanosome A melanosome is an organelle found in animal cells and is the site for synthesis, storage and transport of melanin, the most common light-absorbing pigment found in the animal kingdom. Melanosomes are responsible for color and photoprotectio ...
s. These particles both absorb most of the light, and are sized and shaped so as to scatter rather than reflect most of the rest. Modelling suggests that this camouflage should reduce the distance at which such a fish can be seen by a factor of 6 compared to a fish with a nominal 2% reflectance. Species with this adaptation are widely dispersed in various orders of the
phylogenetic tree A phylogenetic tree or phylogeny is a graphical representation which shows the evolutionary history between a set of species or taxa during a specific time.Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA. In ...
of bony fishes (
Actinopterygii Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class (biology), class of Osteichthyes, bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built ...
), implying that
natural selection Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the Heredity, heritable traits characteristic of a population over generation ...
has driven the
convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last comm ...
of ultra-blackness camouflage independently many times.


Applications


Military


Before 1800

Ship camouflage was occasionally used in ancient times.
Philostratus Philostratus or Lucius Flavius Philostratus (; ; 170s – 240s AD), called "the Athenian", was a Greek sophist of the Roman imperial period. His father was a minor sophist of the same name. He flourished during the reign of Septimius Severus ...
() wrote in his '' Imagines'' that Mediterranean pirate ships could be painted blue-gray for concealment.
Vegetius Publius (or Flavius) Vegetius Renatus, known as Vegetius (), was a writer of the Later Roman Empire (late 4th century). Nothing is known of his life or station beyond what is contained in his two surviving works: ''Epitoma rei militaris'' (also r ...
() says that "Venetian blue" (sea green) was used in the
Gallic Wars The Gallic Wars were waged between 58 and 50 BC by the Roman general Julius Caesar against the peoples of Gaul (present-day France, Belgium, and Switzerland). Gauls, Gallic, Germanic peoples, Germanic, and Celtic Britons, Brittonic trib ...
, when
Julius Caesar Gaius Julius Caesar (12 or 13 July 100 BC – 15 March 44 BC) was a Roman general and statesman. A member of the First Triumvirate, Caesar led the Roman armies in the Gallic Wars before defeating his political rival Pompey in Caesar's civil wa ...
sent his ''speculatoria navigia'' (reconnaissance boats) to gather intelligence along the coast of Britain; the ships were painted entirely in bluish-green wax, with sails, ropes and crew the same colour. There is little evidence of military use of camouflage on land before 1800, but two unusual ceramics show men in
Peru Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...
's Mochica culture from before 500 AD, hunting birds with blowpipes which are fitted with a kind of shield near the mouth, perhaps to conceal the hunters' hands and faces. Another early source is a 15th-century French manuscript, ''The Hunting Book of Gaston Phebus'', showing a horse pulling a cart which contains a hunter armed with a crossbow under a cover of branches, perhaps serving as a hide for shooting game.
Jamaican Maroons Jamaican Maroons descend from Africans who freed themselves from slavery in the Colony of Jamaica and established communities of Free black people in Jamaica, free black people in the island's mountainous interior, primarily in the eastern Pari ...
are said to have used plant materials as camouflage in the
First Maroon War The First Maroon War was a conflict between the Jamaican Maroons and the colonial British authorities that started around 1728 and continued until the peace treaties of 1739 and 1740. It was led by Indigenous Jamaicans who helped Africans to set ...
().


19th-century origins

The development of military camouflage was driven by the increasing range and accuracy of infantry firearms in the 19th century. In particular the replacement of the inaccurate
musket A musket is a muzzle-loaded long gun that appeared as a smoothbore weapon in the early 16th century, at first as a heavier variant of the arquebus, capable of penetrating plate armour. By the mid-16th century, this type of musket gradually dis ...
with weapons such as the
Baker rifle The Pattern 1800 Infantry Rifle, better known as the Baker rifle, was a flintlock rifle designed by English gunsmith Ezekiel Baker and used by the British Armed Forces from 1801 to 1837. First seeing action during the French Revolutionary and Na ...
made personal concealment in battle essential. Two
Napoleonic War {{Infobox military conflict , conflict = Napoleonic Wars , partof = the French Revolutionary and Napoleonic Wars , image = Napoleonic Wars (revision).jpg , caption = Left to right, top to bottom:Battl ...
skirmishing units of the
British Army The British Army is the principal Army, land warfare force of the United Kingdom. the British Army comprises 73,847 regular full-time personnel, 4,127 Brigade of Gurkhas, Gurkhas, 25,742 Army Reserve (United Kingdom), volunteer reserve perso ...
, the 95th Rifle Regiment and the 60th Rifle Regiment, were the first to adopt camouflage in the form of a
rifle green Varieties of the color green may differ in hue, chroma (also called saturation or intensity) or lightness (or value, tone, or brightness), or in two or three of these qualities. Variations in value are also called tints and shades, a tin ...
jacket, while the Line regiments continued to wear scarlet tunics. A contemporary study in 1800 by the English artist and soldier
Charles Hamilton Smith Lieutenant-Colonel Charles Hamilton Smith, Royal Guelphic Order, KH, Military Order of William, KW, Royal Society, FRS, Linnean Society of London, FLS (26 December 1776 – 21 September 1859) was a British Army officer, artist, naturalist, ant ...
provided evidence that grey uniforms were less visible than green ones at a range of 150 yards. In the
American Civil War The American Civil War (April 12, 1861May 26, 1865; also known by Names of the American Civil War, other names) was a civil war in the United States between the Union (American Civil War), Union ("the North") and the Confederate States of A ...
, rifle units such as the 1st United States Sharp Shooters (in the Federal army) similarly wore green jackets while other units wore more conspicuous colours. The first British Army unit to adopt khaki (colour), khaki uniforms was the Corps of Guides (British India), Corps of Guides at Peshawar, when Harry Burnett Lumsden, Sir Harry Lumsden and his second in command, William Stephen Raikes Hodson, William Hodson introduced a "drab" uniform in 1848. Hodson wrote that it would be more appropriate for the hot climate, and help make his troops "invisible in a land of dust". Later they improvised by dyeing cloth locally. Other regiments in India soon adopted the khaki uniform, and by 1896 khaki drill uniform was used everywhere outside Europe; by the Second Boer War six years later it was used throughout the British Army. During the late 19th century camouflage was applied to British coastal fortifications. The fortifications around Plymouth, England were painted in the late 1880s in "irregular patches of red, brown, yellow and green." From 1891 onwards British coastal artillery was permitted to be painted in suitable colours "to harmonise with the surroundings" and by 1904 it was standard practice that artillery and mountings should be painted with "large irregular patches of different colours selected to suit local conditions."


First World War

In the First World War, the French army formed a camouflage corps, led by Lucien-Victor Guirand de Scévola, employing artists known as ''List of camoufleurs, camoufleurs'' to create schemes such as tree observation posts and covers for guns. Other armies soon followed them. The term ''wikt:camouflage, camouflage'' probably comes from ''camoufler'', a Parisian slang term meaning ''to disguise'', and may have been influenced by ''camouflet'', a French language, French term meaning ''smoke blown in someone's face''. The English zoologist John Graham Kerr, artist Solomon J. Solomon and the American artist Abbott Thayer led attempts to introduce scientific principles of countershading and disruptive patterning into military camouflage, with limited success. In early 1916 the Royal Naval Air Service began to create dummy air fields to draw the attention of enemy planes to empty land. They created decoy homes and lined fake runways with flares, which were meant to help protect real towns from night raids. This strategy was not common practice and did not succeed at first, but in 1918 it caught the Germans off guard multiple times. Ship camouflage was introduced in the early 20th century as the range of naval guns increased, with ships painted grey all over. In April 1917, when German U-boats were sinking many British ships with torpedoes, the marine artist Norman Wilkinson (artist), Norman Wilkinson devised dazzle camouflage, which paradoxically made ships more visible but harder to target. In Wilkinson's own words, dazzle was designed "not for low visibility, but in such a way as to break up her form and thus confuse a submarine officer as to the course on which she was heading". File:USS West Mahomet (ID-3681) cropped.jpg, USS ''West Mahomet'' in dazzle camouflage File:CamouflagedAustralian9.2inchHowitzerYpres1917.jpeg, BL 9.2-inch howitzer, Siege howitzer camouflaged against observation from the air, 1917 File:Austro-Hungarian ski patrol on Italian front in snow camouflage 1915-1918.jpg, Austro-Hungarian ski patrol in two-part snow uniforms with improvised head camouflage on Italian front, 1915–1918


Second World War

In the
Second World War World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
, the zoologist Hugh Cott, a protégé of Kerr, worked to persuade the British army to use more effective camouflage methods, including countershading, but, like Kerr and Thayer in the First World War, with limited success. For example, he painted two rail-mounted coastal guns, one in conventional style, one Countershading, countershaded. In aerial photographs, the countershaded gun was essentially invisible. The power of aerial observation and attack led every warring nation to camouflage targets of all types. The Soviet Union's Red Army created the comprehensive military doctrine, doctrine of ''Russian military deception, Maskirovka'' for military deception, including the use of camouflage. For example, during the Battle of Kursk, Mikhail Katukov, General Katukov, the commander of the Soviet 1st Tank Army, remarked that the enemy "did not suspect that our well-camouflaged tanks were waiting for him. As we later learned from prisoners, we had managed to move our tanks forward unnoticed". The tanks were concealed in previously prepared defensive emplacements, with only their turrets above ground level. In the air, Second World War fighters were often painted in ground colours above and sky colours below, attempting two different camouflage schemes for observers above and below. Bombers and night fighters were often black, while maritime reconnaissance planes were usually white, to avoid appearing as dark shapes against the sky. For ships, dazzle camouflage was mainly replaced with plain grey in the Second World War, though experimentation with colour schemes continued. As in the First World War, artists were pressed into service; for example, the surrealist painter Roland Penrose became a lecturer at the newly founded Camouflage Development and Training Centre at Farnham Castle, writing the practical ''Home Guard Manual of Camouflage''. The film-maker Geoffrey Barkas ran the Middle East Command Camouflage Directorate during the 1941–1942 war in the Western Desert, including the successful deception of
Operation Bertram Operation Bertram was a Second World War military deception, deception operation practised by the Allied forces in Egypt led by Bernard Montgomery, in the months before the Second Battle of El Alamein in 1942. Bertram was devised by Dudley Clark ...
. Hugh Cott was chief instructor; the artist camouflage officers, who called themselves ''camoufleurs'', included Steven Sykes (artist), Steven Sykes and Tony Ayrton. In Australia, artists were also prominent in the Sydney Camouflage Group, formed under the chairmanship of Professor William John Dakin, a zoologist from Sydney University. Max Dupain, Sydney Ure Smith, and William Dobell were among the members of the group, which worked at Bankstown Airport, RAAF Base Richmond and Garden Island Dockyard. In the United States, artists like John Vassos took a certificate course in military and industrial camouflage at the American School of Design with Baron Nicholas Cerkasoff, and went on to create camouflage for the Air Force. File:Catalina Góraszka 2008 204.JPG, Maritime patrol Consolidated PBY Catalina, Catalina, painted white to minimise visibility against the sky File:SS Platanenmuster Sommer.jpg, 1937 summer variant of Waffen SS ''Flecktarn'' Plane tree pattern File:USS Duluth (CL-87) underway in Hampton Roads on 10 October 1944 (NH 98363).jpg, USS Duluth (CL-87), USS ''Duluth'' in naval camouflage Measure 32, Design 11a, one of many dazzle schemes used on warships File:Spitfire.planform.arp.jpg, A Supermarine Spitfire, Spitfire's underside 'azure' paint scheme, meant to hide it against the sky File:Royal Air Force 1939-1945- Fighter Command CL3979.jpg, A Luftwaffe aircraft hangar built to resemble a street of village houses, Belgium, 1944 File:Bundesarchiv Bild 183-E0406-0022-001, Russland, Kesselschlacht Stalingrad.jpg, Red Army soldiers in the Battle of Stalingrad in
snow camouflage Snow camouflage is the use of a coloration or pattern for effective camouflage in winter, often combined with a different summer camouflage. Summer patterns are typically disruptively patterned combinations of shades of browns and greys, up to b ...
overalls, January 1943


After 1945

Camouflage has been used to protect military equipment such as vehicles, guns, Ship camouflage, ships, Aircraft camouflage, aircraft and buildings as well as individual soldiers and their positions. Vehicle camouflage methods begin with paint, which offers at best only limited effectiveness. Other methods for stationary land vehicles include covering with improvised materials such as blankets and vegetation, and erecting nets, screens and soft covers which may suitably reflect, scatter or absorb near infrared and
radar Radar is a system that uses radio waves to determine the distance ('' ranging''), direction ( azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method used to detect and track ...
waves. Some military textiles and vehicle camouflage paints also reflect infrared to help provide concealment from image intensification, night vision devices. After the Second World War, radar made camouflage generally less effective, though coastal boats are sometimes painted like land vehicles. Aircraft camouflage too came to be seen as less important because of radar, and aircraft of different air forces, such as the Royal Air Force's English Electric Lightning, Lightning, were often uncamouflaged. Many List of camouflage patterns, camouflaged textile patterns have been developed to suit the need to match Battledress, combat clothing to different kinds of terrain (such as woodland, snow, and desert). The design of a pattern effective in all terrains has proved elusive. The American Universal Camouflage Pattern of 2004 attempted to suit all environments, but was withdrawn after a few years of service. Terrain-specific patterns have sometimes been developed but are ineffective in other terrains. The problem of making a pattern that works at different ranges has been solved with multiscale designs, often with a pixellated appearance and designed digitally, that provide a fractal-like range of patch sizes so they appear disruptively coloured both at close range and at a distance. The first genuinely digital camouflage pattern was the Canadian Disruptive Pattern (CADPAT), issued to the army in 2002, soon followed by the American Marine pattern (MARPAT). A pixellated appearance is not essential for this effect, though it is simpler to design and to print. File:CADPAT digital camouflage pattern (Temperate Woodland variant).jpg, CADPAT was the first pixellated digital camouflage pattern to be issued, in 2002. File:British dpm2.jpg, British Disruptive Pattern Material, issued to Special forces#United Kingdom, special forces in 1963 and universally by 1968 File:M05 snow pattern.jpg, 2007 2-colour snow variant of Finnish Defence Forces M05 pattern File:Pla camo.svg, Main (4-colour woodland) variant of Chinese People's Liberation Army Type 99 (camouflage), Type 99 pattern,