119-439: Trout ( pl. : trout) is a generic common name for numerous species of carnivorous freshwater ray-finned fishes belonging to the genera Oncorhynchus , Salmo and Salvelinus , all of which are members of the subfamily Salmoninae in the family Salmonidae . The word trout is also used for some similar-shaped but non-salmonid fish, such as the spotted seatrout/speckled trout ( Cynoscion nebulosus , which
238-408: A steelhead subspecies, generally accepted as coming from Sonoma Creek . The rainbow trout of New Zealand still show the steelhead tendency to run up rivers in winter to spawn. In Australia, the rainbow trout was introduced in 1894 from New Zealand and is an extremely popular gamefish in recreational angling. Despite severely impacting the distribution and abundance of native Australian fish, such as
357-450: A backbone like snails, worms, or insects. They also eat flies, and most people who try to use lures to fish trout mimic flies because they are one of trout's most fed on meals. Trout enjoy certain land animals, including insects like grasshoppers. They also eat small animals like mice when they fall in. (Although only large trout have mouths capable of eating mice.) They consume a diet of aquatic life like minnows or crawfish as well. Trout have
476-436: 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 , such as the firefly squid and the midwater squid . The latter has light-producing organs ( photophores ) scattered all over its underside; these create a sparkling glow that prevents the animal from appearing as a dark shape when seen from below. Counterillumination camouflage
595-420: A broad category of actions. For example, verbs such as stare , gaze , view and peer can also be considered hyponyms of the verb look , which is their hypernym. The meaning relation between hyponyms and hypernyms applies to lexical items of the same word class (that is, part of speech) , and holds between senses rather than words. For instance, the word screwdriver used in the previous example refers to
714-429: A clear evolutionary advantage in plants: they would tend to escape from being eaten by herbivores . 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. Some animals, such as
833-403: A combination of the two. 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 and dragonflies use motion camouflage : the hoverflies to approach possible mates, and the dragonflies to approach rivals when defending territories. Motion camouflage
952-408: A condition known as physostome . Unlike many other physostome fish, trout do not use their bladder as an auxiliary device for oxygen uptake, relying solely on their gills . There are many species, and even more populations, that are isolated from each other and morphologically different. However, since many of these distinct populations show no significant genetic differences, what may appear to be
1071-594: A diverse diet they follow; they have plenty of different oppositions. Compared to other salmonids, trout are somewhat more bony , but the flesh is generally considered delicious, and the texture is often indistinguishable from that of salmon . The flavor of the flesh is heavily influenced by the diet of the fish. For example, trout that have been feeding on crustaceans tend to be more flavorful than those feeding primarily on insects and larvae . Because of their popularity, trout are often raised on fish farms and then stocked into heavily fished waters, in an effort to mask
1190-523: A dog, it's a bitch" ("That hypernym Z isn't a hyponym Z, it's a hyponym Y"). The term "autohyponym" was coined by linguist Laurence R. Horn in a 1984 paper, Ambiguity, negation, and the London School of Parsimony. Linguist Ruth Kempson had already observed that if there are hyponyms for one part of a set but not another, the hypernym can complement the existing hyponym by being used for the remaining part. For example, fingers describe all digits on
1309-442: 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 of bony fishes ( Actinopterygii ), implying that natural selection has driven the convergent evolution of ultra-blackness camouflage independently many times. In mimesis (also called masquerade ), the camouflaged object looks like something else which
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#17327725682421428-600: A force the native salmon and trout have to reckon with. Not only do the non-native fish drive the native fish to occupy new niches, but they also try to hybridize with them, contaminating the native gene construction. As more hybrids between native and non-native fish are formed, the lineage of the pure fish is continuously being contaminated by other species and soon may no longer represent the sole native species. The Rio Grande cutthroat trout ( Oncorhynchus clarki virginalis ) are susceptible to hybridization with other salmonids such as rainbow trout ( Oncorhynchus mykiss ) and yield
1547-696: A good fight when caught with a hook and line . As trout are predatory fish , lure fishing (which use replica baits called lures to imitate live prey) is the predominant form of sport fishing involving trout, although traditional bait fishing techniques using floats and/or sinkers (particularly with moving live baits such as baitfish , crayfish or aquatic insects ) are also successful, especially against stocked trout that are hatchery / farm -raised and thus more accustomed to artificial feeds . Many species of trout, most noticeably rainbow trout and brown trout , have been widely introduced into waterbodies outside of their native ranges purely for
1666-412: A hand, but the existence of the word thumb for the first finger means that fingers can also be used for "non-thumb digits on a hand". Autohyponymy is also called "vertical polysemy ". Horn called this "licensed polysemy ", but found that autohyponyms also formed even when there is no other hyponym. Yankee is autohyponymous because it is a hyponym (native of New England) and its hypernym (native of
1785-475: 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
1904-477: A large number of species is considered a much smaller number of distinct species by most ichthyologists . The trout found in the eastern United States are a good example of this. The brook trout , the aurora trout , and the (extinct) silver trout all have physical characteristics and colorations that distinguish them, yet genetic analysis shows that they are one species, Salvelinus fontinalis . Lake trout ( Salvelinus namaycush ), like brook trout, belong to
2023-478: A large part of the diet. In general, trout longer than about 300 millimetres (12 in) prey almost exclusively on fish, where they are available. Adult trout will devour smaller fish up to one-third of their length. Trout may feed on shrimp , mealworms , bloodworms , insects , small animal parts, and eel . Trout who swim the streams love to feed on land animals, aquatic life, and flies. Most of their diet comes from macroinvertebrates, or animals that do not have
2142-519: A mirror oriented vertically makes animals such as fish invisible from the side. Most fish in the upper ocean such as sardine and herring are camouflaged by silvering. The marine hatchetfish is extremely flattened laterally, leaving the body just millimetres thick, and the body is so silvery as to resemble aluminium foil . The mirrors consist of microscopic structures similar to those used to provide structural coloration : stacks of between 5 and 10 crystals of guanine spaced about 1 ⁄ 4 of
2261-498: A more general word than its hyponym, the relation is used in semantic compression by generalization to reduce a level of specialization . The notion of hyponymy is particularly relevant to language translation , as hyponyms are very common across languages. For example, in Japanese the word for older brother is ani ( 兄 ) , and the word for younger brother is otōto ( 弟 ) . An English-to-Japanese translator presented with
2380-429: A new " cutbow " trout, which is a contamination of both lineages’ genes. One solution to this issue is implemented by New Mexico Department of Game and Fish hatcheries : stock only sterile fish in river streams. Hatcheries serve as a reservoir of fish for recreational activities but growing and stocking non-sterile fish would worsen the hybridization issue on a quicker, more magnified time scale. By stocking sterile fish,
2499-404: 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 , melanosomes . 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
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#17327725682422618-411: 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
2737-537: A phrase containing the English word brother would have to choose which Japanese word equivalent to use. This would be difficult, because abstract information (such as the speakers' relative ages) is often not available during machine translation . Camouflage 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
2856-502: A predator blends in with the background, enabling it to approach prey). His experiments showed that swallow-tailed moth pupae were camouflaged to match the backgrounds on which they were reared as larvae . Poulton's "general protective resemblance" was at that time considered to be the main method of camouflage, as when Frank Evers Beddard wrote in 1892 that "tree-frequenting animals are often green in colour. Among vertebrates numerous species of parrots , iguanas , tree-frogs , and
2975-409: A reason, such as to lure prey. For example, the nematocysts (stinging cells) of the transparent siphonophore Agalma okenii resemble small copepods . Examples of transparent marine animals include a wide variety of larvae , including radiata (coelenterates), siphonophores, salps (floating tunicates ), gastropod molluscs , polychaete worms, many shrimplike crustaceans , and fish; whereas
3094-693: A reproductive advantage, enabling them to leave more offspring, on average, than other members of the same species . In his Origin of Species , Darwin wrote: When we see leaf-eating insects green, and bark-feeders mottled-grey; the alpine ptarmigan white in winter, the red-grouse the colour of heather , and the black-grouse that of peaty earth, we must believe that these tints are of service to these birds and insects in preserving them from danger. Grouse, if not destroyed at some period of their lives, would increase in countless numbers; they are known to suffer largely from birds of prey ; and hawks are guided by eyesight to their prey, so much so, that on parts of
3213-505: 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 , Arctic fox , stoat , and rock ptarmigan have snow camouflage , changing their coat colour (by moulting and growing new fur or feathers) from brown or grey in
3332-588: A source of nutrients for scavengers , detrivores and riparian florae , making trout keystone species across aquatic and terrestrial ecosystems . The name "trout" is commonly used for many (if not most) species in three of the seven genera in the subfamily Salmoninae: Salmo ( Atlantic ), Oncorhynchus ( Pacific ) and Salvelinus ( circum - arctic ). Fish species referred to as trout include: Trout that live in different environments can have dramatically different colorations and patterns. Mostly, these colors and patterns form as camouflage , based on
3451-416: A species of nudibranch that feeds on stony coral , 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
3570-409: 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
3689-615: Is "An X is a kind/type of Y". The second relation is said to be more discriminating and can be classified more specifically under the concept of taxonomy. If the hypernym Z consists of hyponyms X and Y, then X and Y are identified as co-hyponyms (cohyponyms), also known as coordinate terms. Co-hyponyms are labelled as such when separate hyponyms share the same hypernym but are not hyponyms of one another, unless they happen to be synonymous. For example, screwdriver , scissors , knife , and hammer are all co-hyponyms of one another and hyponyms of tool , but not hyponyms of one another: *"A hammer
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3808-441: Is "type of", whereas "instance of" is differentiable. For example, for the noun city , a hyponym (naming a type of city) is capital city or capital , whereas Paris and London are instances of a city, not types of city. In linguistics , semantics , general semantics , and ontologies , hyponymy (from Ancient Greek ὑπό ( hupó ) 'under' and ὄνυμα ( ónuma ) 'name') shows
3927-400: Is a hyponym of color . A word can be both a hypernym and a hyponym: for example purple is a hyponym of color but itself is a hypernym of the broad spectrum of shades of purple between the range of crimson and violet . The hierarchical structure of semantic fields can be seen in hyponymy. They could be observed from top to bottom, where the higher level is more general and the lower level
4046-431: Is a type of knife " is false. Co-hyponyms are often but not always related to one another by the relation of incompatibility. For example, apple , peach and plum are co-hyponyms of fruit . However, an apple is not a peach , which is also not a plum . Thus, they are incompatible. Nevertheless, co-hyponyms are not necessarily incompatible in all senses . A queen and mother are both hyponyms of woman but there
4165-452: Is acellular and highly transparent. This conveniently makes them buoyant , 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 planktonic 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 at a depth of 650 metres (2,130 ft); better transparency
4284-475: 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 back and forth by the breeze. 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
4403-564: Is actually a croaker ). Trout are closely related to salmon and have similar migratory life cycles . Most trout are strictly potamodromous , spending their entire lives exclusively in freshwater lakes , rivers and wetlands and migrating upstream to spawn in the shallow gravel beds of smaller headwater creeks . The hatched fry and juvenile trout, known as alevin and parr , will stay upstream growing for years before migrating down to larger waterbodies as maturing adults . There are some anadromous species of trout, such as
4522-433: Is an important component of camouflage in all environments. For instance, tree-dwelling parakeets are mainly green; woodcocks of the forest floor are brown and speckled; reedbed bitterns are streaked brown and buff; in each case the animal's coloration matches the hues of its habitat. Similarly, desert animals are almost all desert coloured in tones of sand, buff, ochre, and brownish grey, whether they are mammals like
4641-436: 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 was little studied until the late 20th century. Leaf variegation with white spots may serve as camouflage in forest understory plants, where there is a dappled background; leaf mottling is correlated with closed habitats. Disruptive camouflage would have
4760-516: Is autohyponymous because "smell" can also mean "to emit a bad smell", even though there is no "to emit a smell that isn't bad" hyponym. Hyperonym and hypernym mean the same thing, with both in use by linguists. The form hypernym interprets the -o- of hyponym as a part of hypo , such as in hypertension and hypotension . However, etymologically the -o- is part of the Greek stem ónoma . In other combinations with this stem, e.g. synonym , it
4879-418: 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. For example, although giraffes have
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4998-435: 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 has been preserved with countershading . Camouflage does not have a single genetic origin. However, studying
5117-403: 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
5236-525: Is less often used for military camouflage, despite Second World War experiments that showed its effectiveness. English zoologist Hugh Cott 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
5355-434: Is mediated by a type of chromatophore known as melanophores that contain dark pigment. A melanophore is star-shaped; it contains many small pigmented organelles 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,
5474-400: Is more specific. For example, living things will be the highest level followed by plants and animals , and the lowest level may comprise dog , cat and wolf . Under the relations of hyponymy and incompatibility, taxonomic hierarchical structures too can be formed. It consists of two relations; the first one being exemplified in "An X is a Y" (simple hyponymy) while the second relation
5593-660: Is much cheaper than the imported Atlantic salmon and the meat are indistinguishable to the untrained eyes, and the news of trout being sold as salmon triggered public scrutiny accusing seafood suppliers of bait-and-switch and unethical business practices . Also, many people believe freshwater trout are more prone to parasites than oceanic salmon (even though both live in freshwater for significant periods of their life cycles) and thus unsafe for raw eating . One fillet of trout (about 79 g or 2.8 oz) contains: Trout are very popular freshwater game fish highly prized especially by creek fishermen, because they generally put up
5712-412: Is never elided. Therefore, hyperonym is etymologically more faithful than hypernym . Hyperonymy is used, for instance, by John Lyons, who does not mention hypernymy and prefers superordination . The nominalization hyperonymy is rarely used, because the neutral term to refer to the relationship is hyponymy . Computer science often terms this relationship an " is-a " relationship. For example,
5831-540: 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 . The English zoologist Hugh Cott 's 1940 book Adaptive Coloration in Animals corrected Thayer's errors, sometimes sharply: "Thus we find Thayer straining
5950-416: Is nothing preventing the queen from being a mother . This shows that compatibility may be relevant. A word is an autohyponym if it is used for both a hypernym and its hyponym: it has a stricter sense that is entirely a subset of a broader sense. For example, the word dog describes both the species Canis familiaris and male individuals of Canis familiaris , so it is possible to say "That dog isn't
6069-739: Is possible that some plants use camouflage to evade being eaten by herbivores . Military camouflage was spurred by the increasing range and accuracy of firearms in the 19th century. In particular the replacement of the inaccurate musket with the rifle made personal concealment in battle a survival skill. In the 20th century, military camouflage developed rapidly, especially during the First World War . On land, artists such as André Mare designed camouflage schemes and observation posts disguised as trees. At sea , merchant ships and troop carriers were painted in dazzle patterns that were highly visible, but designed to confuse enemy submarines as to
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#17327725682426188-463: 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 muscles can be made transparent, provided either they are very thin or organised as regular layers or fibrils that are small compared to
6307-483: Is the likely function of the bioluminescence 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 " 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
6426-428: 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 formulated what is sometimes called Thayer's Law, the principle of countershading . However, he overstated
6545-474: 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 , 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). This
6664-640: Is unique as an instance of camouflage arising as an instance of horizontal gene transfer from an endosymbiont . However, other methods of horizontal gene transfer are common in the evolution of camouflage strategies in other lineages. Peppered moths and walking stick insects both have camouflage-related genes that stem from transposition events. The Agouti genes are orthologous genes involved in camouflage across many lineages. They produce yellow and red coloration ( phaeomelanin ), and work in competition with other genes that produce black (melanin) and brown (eumelanin) colours. In eastern deer mice , over
6783-463: Is virtually impossible to define a particular color pattern as belonging to a specific breed; however, in general, wild fish are claimed to have more vivid colors and patterns. Trout have fins entirely without spines, and all of them have a small adipose fin along the back, near the tail. The pelvic fins sit well back on the body, on each side of the anus. The swim bladder is connected to the esophagus , allowing for gulping or rapid expulsion of air,
6902-656: The climbing galaxias , millions of rainbow and other trout species are released annually from government and private hatcheries. The closest resemblance of seema trout and other trout family can be found in the Himalayan Region of India, Nepal, Bhutan, Pakistan and in Tian Shan mountains of Kyrgyzstan . Trout generally feed on other fish, and soft-bodied aquatic invertebrates , such as flies , mayflies , caddisflies , stoneflies , mollusks and dragonflies . In lakes, various species of zooplankton often form
7021-548: The gerbil or fennec fox , birds such as the desert lark or sandgrouse , or reptiles like the skink or horned viper . Military uniforms, too, generally resemble their backgrounds; for example khaki uniforms are a muddy or dusty colour, originally chosen for service in South Asia. Many moths show industrial melanism , including the peppered moth which has coloration that blends in with tree bark. The coloration of these insects evolved between 1860 and 1940 to match
7140-409: The green tree-snake are examples". Beddard did however briefly mention other methods, including the "alluring coloration" of the flower mantis 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 [an umbellifer ], so close
7259-401: The horned lizards of North America, have evolved elaborate measures to eliminate shadow . Their bodies are flattened, with the sides thinning to an edge; the animals habitually press their bodies to the ground; and their sides are fringed with white scales which 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
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#17327725682427378-442: The leopard 's spotted coat, the battledress of a modern soldier , 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, often through a general resemblance to the background, high contrast disruptive coloration , eliminating shadow, and countershading . In
7497-408: The screwdriver tool , and not to the screwdriver drink . Hypernymy and hyponymy are converse relations . If X is a kind of Y, then X is a hyponym of Y and Y is a hypernym of X. Hyponymy is a transitive relation : if X is a hyponym of Y, and Y is a hyponym of Z, then X is a hyponym of Z. For example, violet is a hyponym of purple and purple is a hyponym of color ; therefore violet
7616-478: The semantic relations between a generic term (hypernym) and a more specific term (hyponym). The hypernym is also called a supertype, umbrella term, or blanket term. The hyponym names a subtype of the hypernym. The semantic field of the hyponym is included within that of the hypernym. For example, pigeon , crow , and hen are all hyponyms of bird and animal ; bird and animal are both hypernyms of pigeon, crow, and hen . A core concept of hyponymy
7735-993: The steelhead (a coastal subspecies of rainbow trout ) and sea trout (the sea-run subspecies of brown trout ), that can spend up to three years of their adult lives at sea before returning to freshwater streams for spawning, in the same fashion as a salmon run . Brook trout and three other extant species of North American trout, despite the names, are actually char (or charr) , which are salmonids also closely related to trout and salmon. Trout are classified as oily fish and have been important food fish for humans . As mid-level predators , trout prey upon smaller aquatic animals including crustaceans , insects , worms , baitfish and tadpoles , and themselves in turn are also important staple prey items for many wildlifes including brown bears , otters , raccoons , birds of prey (e.g. sea eagles , ospreys , fish owls ), gulls , cormorants and kingfishers , and other large aquatic predators. Discarded remains of trout also provide
7854-600: 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 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, [gun] battery positions, observation posts and so forth." Movement catches
7973-663: The Continent persons are warned not to keep white pigeons, as being the most liable to destruction. Hence I can see no reason to doubt that natural selection might be most effective in giving the proper colour to each kind of grouse, and in keeping that colour, when once acquired, true and constant. The English zoologist Edward Bagnall Poulton studied animal coloration , especially camouflage. In his 1890 book The Colours of Animals , he classified different types such as "special protective resemblance" (where an animal looks like another object), or "general aggressive resemblance" (where
8092-463: The United States), even though there is no other hyponym of Yankee (as native of the United States) that means "not a native of New England". Similarly, the verb to drink (a beverage) is a hypernym for to drink (an alcoholic beverage). In some cases, autohyponyms duplicate existing, distinct hyponyms. The hypernym "smell" (to emit any smell) has a hyponym "stink" (to emit a bad smell), but
8211-409: The adults of most of these are opaque and pigmented, resembling the seabed or shores where they live. Adult comb jellies 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
8330-483: The agouti gene shows that different organisms often rely on orthologous or even identical genes to develop a variety of camouflage strategies. 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 are less likely to be detected when in that microhabitat, but must spend energy to reach, and sometimes to remain in, such areas. Outside
8449-438: 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
8568-456: 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 wears a ghillie suit 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,
8687-442: 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
8806-457: 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 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. Counter-illumination means producing light to match
8925-468: 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 ' mark, not one ' warning color '... nor any ' sexually selected ' color, exists anywhere in the world where there
9044-403: The change is controlled relatively slowly, mainly by hormones . 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
9163-411: 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. Disruptive patterns use strongly contrasting, non-repeating markings such as spots or stripes to break up
9282-485: The char genus. Lake trout inhabit many of the larger lakes in North America, and live much longer than rainbow trout , which have an average maximum lifespan of seven years. Lake trout can live many decades, and can grow to more than 30 kilograms (66 lb). As salmonids, trout are coldwater fish that are usually found in cool (50–60 °F or 10–16 °C), clear streams, wetlands and lakes, although many of
9401-540: The colour-changing abilities, both for camouflage and for signalling , of cephalopods including the octopus, in his Historia animalium : The octopus ... seeks its prey by so changing its colour as to render it like the colour of the stones adjacent to it; it does so also when alarmed . Camouflage has been a topic of interest and research in zoology for well over a century. According to Charles Darwin 's 1859 theory of natural selection , features such as camouflage evolved by providing individual animals with
9520-411: 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 similarly relies on a combination of methods: it is adapted to lie flat in
9639-504: 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 , such as gazelles and grasshoppers; marine animals, such as sharks and dolphins ; and birds, such as snipe and dunlin . Countershading
9758-575: The day and larger trout crowding in during morning and evening feeding periods. Fishing for trout under the ice generally occurs in depths of 4 to 8 feet (1.2 to 2.4 m). Because trout are cold water fish, during the winter they move from up-deep to the shallows, replacing the small fish that inhabit the area during the summer. Trout in winter constantly cruise in shallow depths looking for food, usually traveling in groups, although bigger fish may travel alone and in water that's somewhat deeper, around 12 feet (3.7 m). Rainbow, Brown, and Brook trout are
9877-551: The effects of overfishing . Farmed trout are also sold commercially as seafood , although they are not saltwater fish . Trout meat is typically prepared the same way as salmon, often by smoking . In Mainland China , farm-raised rainbow trout from Qinghai was officially sanctioned to be labeled and sold domestically as salmon, which caused much controversy regarding food safety and consumer rights violation , as raw fish dishes or yusheng using Atlantic salmon are gaining popularity in southern China . Farmed rainbow trout
9996-502: 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. Camouflage can be achieved by different methods, described below. Most of
10115-419: 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 , moving with extreme stealth, both slowly and quietly, watching its prey for any sign they are aware of its presence. As an example of
10234-400: The features of their bodies, and to match their backgrounds. For example, a caddisfly larva builds a decorated case and lives almost entirely inside it; a decorator crab covers its back with seaweed, sponges, and stones. The nymph 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 ( trichomes ) over
10353-738: 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 , including squid, octopus and cuttlefish, have multilayer mirrors made of protein rather than guanine. 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 had
10472-482: The genetic components and various ecological pressures that drive crypsis. Camouflage is a soft-tissue feature that is rarely preserved in the fossil record, but rare fossilised skin samples from the Cretaceous period show that some marine reptiles were countershaded. The skins, pigmented with dark-coloured eumelanin , reveal that both leatherback turtles and mosasaurs had dark backs and light bellies. There
10591-436: The genetic components of camouflage in specific organisms illuminates the various ways that crypsis can evolve among lineages. Many cephalopods 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
10710-399: 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
10829-423: The local environment. 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 ). Thus, studying the evolution of camouflage strategies requires an understanding of
10948-534: The method mainly for its efficiency rather than camouflage. Animals such as chameleon , frog, flatfish such as the peacock flounder , squid, octopus and even the isopod idotea balthica actively change their skin patterns and colours using special chromatophore cells to resemble their current background, or, as in most chameleons, for signalling . 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
11067-428: 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 (scent) and acoustic (sound) detection. Methods may also apply to military equipment. Some animals' colours and patterns match a particular natural background. This
11186-466: 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 melanocrachia ,
11305-741: The most common trout species caught through the ice. By information from International Game Fish Association (IGFA), the most outstanding records are: Salmonid populations in general have been declining due to numerous factors, including invasive species , hybridization, wildfires, and climate change. Native salmonid fish in the western and southwestern United States are threatened by non-native species that were introduced decades ago. Non-native salmonids were introduced to enrich recreational fishing; however, they quickly started outcompeting and displacing native salmonids upon their arrival. Non-native, invasive species are quick to adapt to their new environment and learn to outcompete any native species, making them
11424-485: The native Gila trout will be evacuated from streams that are threatened by nearby fires and be reintroduced after the threat is resolved. Climate change is also dwindling native salmonid populations. Global warming continually affects various cold-water fish such as trout, especially as inland waterbodies are more prone to warming than oceans. With an increase of temperature along with changes in spawning river flow, an abundance of trout species are effected negatively. In
11543-531: The native salmonids can't share genes with the non-native hatchery fish, thus, preventing further gene contamination of the native trout in New Mexico. Fire is also a factor in deteriorating Gila trout ( Oncorhynchus gilae ) populations because of the ash and soot that can enter streams following fires. The ash lowers water quality, making it more difficult for the Gila trout to survive. In some New Mexico streams,
11662-538: The night sky, requiring awkward external platforms to support the lamps. The Canadian concept was refined in the American Yehudi lights project, and trialled in aircraft including B-24 Liberators and naval Avengers . 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 3,000 yards (2,700 m) – before being seen. Counterillumination
11781-514: 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
11900-442: The open ocean, where there is no background, the principal methods of camouflage are transparencying, silveringing, and countershading, while the ability to produce light is among other things used for counter-illumination on the undersides of cephalopods such as squid . Some animals, such as chameleons and octopuses , are capable of actively changing their skin pattern and colors , whether for camouflage or for signalling. It
12019-408: The outlines of an animal or military vehicle, or to conceal telltale features, especially by masking the eyes , as in the common frog . Disruptive patterns may use more than one method to defeat visual systems such as edge detection . Predators like the leopard use disruptive camouflage to help them approach prey, while potential prey use it to avoid detection by predators. Disruptive patterning
12138-498: The past, a mere 8 °F (4.4 °C) increase was predicted to eliminate half of the native brook trout in the Southern Appalachian Mountains . Trout generally prefer streams with colder water (50–60 °F or 10–16 °C) to spawn and thrive, but raising water temperatures are altering this ecosystem and further deteriorate native populations. Umbrella term Hypernymy and hyponymy are
12257-400: The phrase "Red is-a color" can be used to describe the hyponymic relationship between red and color . Hyponymy is the most frequently encoded relation among synsets used in lexical databases such as WordNet . These semantic relations can also be used to compare semantic similarity by judging the distance between two synsets and to analyse anaphora . As a hypernym can be understood as
12376-652: The relationship between a generic term (hypernym) and a specific instance of it (hyponym). A hyponym is a word or phrase whose semantic field is more specific than its hypernym. The semantic field of a hypernym, also known as a superordinate, is broader than that of a hyponym. An approach to the relationship between hyponyms and hypernyms is to view a hypernym as consisting of hyponyms. This, however, becomes more difficult with abstract words such as imagine , understand and knowledge . While hyponyms are typically used to refer to nouns, it can also be used on other parts of speech. Like nouns, hypernyms in verbs are words that refer to
12495-496: The sake of recreational fishing , and some of these introduced populations have even become invasive in the new habitats. While trout can be caught with a normal rod and reel , fly fishing is a distinctive lure fishing method developed for trout, and now extended to other species. Due to the high proportion of insects and small crustaceans within the trout's diet, small lures made of hand-tied hairs and threads are often used to imitate these aquatic invertebrates that
12614-474: The same time in Australia , 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
12733-467: 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. 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
12852-477: 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. 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
12971-527: The species have anadromous populations as well. Juvenile trout are referred to as troutlet, troutling or parr. They are distributed naturally throughout North America , northern Asia and Europe . Several species of trout were introduced to Australia and New Zealand by amateur fishing enthusiasts in the 19th century, effectively displacing and endangering several upland native fish species. The introduced species included brown trout from England and rainbow trout from California . The rainbow trout has
13090-462: The speckled wood, Pararge aegeria , 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 , select a resting position facing the sun. Eliminating shadow
13209-722: 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 , 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 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 announced their Adaptiv infrared camouflage technology. It uses about 1,000 hexagonal panels to cover
13328-501: The surroundings, and will change as the fish moves to different habitats. Trout in, or newly returned from the sea, can look very silvery, while the same fish living in a small stream or in an alpine lake could have pronounced markings and more vivid coloration; it is also possible that in some species, this signifies that they are ready to mate. In general, trout that are about to breed have extremely intense coloration and can look like an entirely different fish outside of spawning season. It
13447-835: The target's speed, range, and heading. During and after the Second World War , a variety of camouflage schemes were used for aircraft 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. In ancient Greece, Aristotle (384–322 BC) commented on
13566-470: 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 worked, using streaks of boldly contrasting colour, paradoxically making objects less visible by breaking up their outlines. While Cott
13685-551: The trout prey upon. These ultralight fly lures cannot be cast adequately by conventional techniques, and a specialized heavy line (i.e. fly line) is needed to launch the lure. Understanding how moving water shapes the stream channel makes it easier to find trout. In most streams, the current creates a riffle-run-pool pattern that repeats itself over and over. A deep pool may hold a big brown trout, but rainbow trout and smaller brown trout are likely found in runs. Riffles are where fishers will find small trout, called troutlet, during
13804-508: The wavelength of visible light. A familiar example is the transparency of the lens of the vertebrate eye , which is made of the protein crystallin , and the vertebrate cornea which is made of the protein collagen . Other structures cannot be made transparent, notably the retinas or equivalent light-absorbing structures of eyes – they must absorb light to be able to function. The camera -type eye of vertebrates and cephalopods must be completely opaque. Finally, some structures are visible for
13923-682: Was identified as a principle of military camouflage during the Second World War . 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 tits increased when artificial prey had distractive markings. 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
14042-464: Was made obsolete by radar , and neither diffused lighting camouflage nor Yehudi lights entered active service. 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 from seawater. Some marine animals such as jellyfish have gelatinous bodies, composed mainly of water; their thick mesogloea
14161-498: 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 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 and coursers ) were shown to survive according to how well their egg contrast matched
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