Deception in animals is the voluntary or involuntary transmission of misinformation by one animal to another, of the same or different species, in a way that misleads the other animal. Robert Mitchell identifies four levels of deception in animals. At the first level, as with protective mimicry like false eyespots and camouflage, the action or display is inbuilt. At the second level, an animal performs a programmed act of behaviour, as when a prey animal feigns death to avoid being eaten. At the third level, the deceptive behaviour is at least partially learnt, as when a bird puts on a distraction display, feigning injury to lure a predator away from a nest. Fourth level deception involves recognition of the other animal's beliefs, as when a chimpanzee tactically misleads other chimpanzees to prevent their discovering a food source.
Some types of deception in animals are completely involuntary (e.g. disruptive coloration), but others are under voluntary control and may involve an element of learning. Most instances of voluntary deception in animals involve a simple behaviour, such as a cat arching its back and raising its hackles, to make itself appear larger than normal when attacked. There are relatively few examples of animal behaviour which might be attributed to the manipulative type of deception which we know occurs in humans, i.e. "tactical deception". It has been argued that true deception assumes the deceiver knows that (1) other animals have minds, (2) different animals' minds can believe different things are true (when only one of these is actually true), and (3) it can make another mind believe that something false is actually true. True deception requires the deceiver to have the mental capacity to assess different representations of reality. Animal behaviour scientists are therefore wary of interpreting a single instance of behaviour as true deception, and explain it with simpler mental processes such as learned associations. [1] In contrast, human activities such as military deception are certainly intentional, even when they involve methods such as camouflage which physically parallel camouflage methods used by animals. [2]
Robert Mitchell lists four levels of deception in animals: [3]
All four levels are found in nature, including bacteria and plants, but the third and fourth levels seem to be exclusive to animals. [4]
At the first level, an animal acts because it cannot do otherwise, it is programmed to deceive in a certain way. For example, false eyespots such as butterfly markings that indicate their heads are at the back end of their bodies as an aid to escape. [3]
Mimicry is a resemblance of one species to another which protects one or both species. The can be in visual appearance, behaviour, sound, and scent. There are many types, which can be combined. [5] Defensive or protective mimicry enables organisms are able to avoid encounters that would be harmful to them by deceiving enemies by appearing to be something that they are not. For example, mantis shrimps spread their powerful front limbs to threaten rivals in a behaviour called the "meral spread". [6] Newly moulted mantis shrimps frequently deceive potential competitors by spreading their front limbs, even though their still-soft exoskeletons meant that they could not use their smashers without damaging themselves. [7] [6]
Aggressive mimicry is the mimicking by predators or parasites of harmless species, allowing the predator to approach and sometimes to attract its prey. [8] Anglerfish are named for their characteristic method of predation. Anglerfish typically have at least one long filament (the illicium) sprouting from the middle of the head, protruding above the fish's eyes and terminating in an irregular growth of flesh (the esca ) at the tip of the filament. The filament can move in all directions and the esca can be wiggled so as to resemble a prey animal, thus acting as bait to lure other predators close enough for the anglerfish to devour them. [8] Some deep-sea anglerfishes of the bathypelagic zone emit light from their escas to attract prey. This bioluminescence is a result of symbiosis with bacteria. [9] [10] Among fireflies, males are lured toward what seems to be a sexually receptive female, only to be eaten. Photuris females emit the same light signals that females of the genus Photinus emit as a mating signal. [11] Male fireflies from several different genera are attracted to these "femmes fatales" because the predatory females can identify the male's species and emit the signal used by the female of the male's species. [11]
In automimicry, one body part of an animal mimics another. This may help and animal survive an attack, or help predators to appear innocuous. Examples include many moth, butterfly, and fish species that have "eye-spots". These are large dark markings that help prey escape by causing predators to attack a false target. For example, the gray hairstreak ( Strymon melinus ) shows the false head at its rear; it has a better chance of surviving an attack to that part than an attack to the head. [12]
Camouflage is the use of any combination of materials, coloration, or behaviour that helps to conceal an animal by making it hard to see (crypsis) or by disguising it as something else (mimesis). There are many methods of achieving crypsis. These include, resemblance to the surroundings, disruptive coloration, eliminating shadow, self-decoration, cryptic behaviour, motion camouflage, changeable skin appearance, countershading, counter-illumination, transparency, and silvering to reflect the environment. Many species are cryptically coloured to resemble their surroundings. For example, Uroplatus geckos can be almost completely invisible, even to a nearby observer. Similarly, the katydids, a group of grasshopper-like insects found worldwide, are nocturnal and use their cryptic colouration to remain unnoticed during the day. They remain perfectly still, often in a position that increases the effectiveness of their camouflage. [13] [14]
At the second level, an animal conducts a programmed act of behaviour when another organism is registered. Examples include a predator's behaving in such a way as to hide its predatory nature around prey. [3]
A well-researched form of deception is feigning death, familiarly known as "playing dead" or "playing possum", although specialists use the terms "tonic immobility" or "thanatosis". A wide range of animals, e.g. lizards, birds, rodents, and sharks, behave as if dead as an anti-predator adaptation, as predators usually take only live prey. [15]
In beetles, artificial selection experiments have shown that there is heritable variation for length of death-feigning. Those selected for longer death-feigning durations are at a selective advantage to those at shorter durations when a predator is introduced. [16] Birds often feign death to escape predation; for example tonic immobility in quail reduces the probability of attacks by cats. [17]
Death feigning may also play a role in reproduction, for example, in the nursery web spider, the male sometimes feigns death to avoid getting eaten by females during mating. [18] In some cases, death feigning is used by a predator. For example, the predatory cichlid Nimbochromis livingstonii lies on its side on the bottom sediments until approached by scavengers attracted to what appears to be a dead fish, whereupon H. livingstoni abandons the pretence, rights itself and attacks the scavenger. [19]
The third level involves learning, and is based upon trial and error. An example is a distraction display of feigned injury to get or divert attention; for example, a parent mockingbird feigning an injury to attract a predator away from its defenceless offspring. [3]
Distraction displays, also known as deflection displays and diversionary displays, [20] are behaviours that draw the attention of a predator away from an object, typically the nest or young. [21] These are well known in birds, as first described by Aristotle in the 4th century BC, [22] but also occur in fish. [23] A familiar example is the broken-wing display seen in nesting waders, plovers and doves such as the mourning dove. In this display, a bird walks away from its nest with one wing dragging on the ground. It seems to be an easy target, thus distracting the predator's attention away from the nest. Once the bird is far enough away it "recovers" and quickly flies off. [24]
Mitchell [3] has proposed that self-deception occurs if the deceiver and the object of deception are the same organism. Two approaches are tied to self-deception: intentionalism (self-deception is an intentional act) and revisionism (self-deception is not an intensional act). In both cases, there is a higher-level theory of mind present. Namely, intentionality is tied to the third and fourth level of deception, especially the fourth. [4] For Mitchell and for Šekrst, intentionality can only be analyzed at the third level, but not as the animal being intentionally deceptive (having recognition of what the other animal effecting that result believes about the action). [4]
Cases of self-deception have been found in the animal world as well regarding dishonest behaviour of slender crayfish (Cherax dispar). [25] Šekrst [4] uses the findings to show that if we consider this case to be a case of self-deception, then we are acknowledging beliefs, in which case we must talk about first-order intentionality and at least Mitchell's third level of deception. Angiletta et al. show that to establish adaptive self-deception, biologists must quantify the cost and benefit of ignoring one's true competitive ability: in this case, deceptive signallers largely ignored their own strength when escalating or evading aggression. [26]
Angiletta et al. established two conditions for self-deception. First, dishonest individuals must escalate aggression using the same signals that honest individuals do. Second, both dishonest individuals and honest individuals must escalate aggression according to the quality they have signaled, regardless of their actual quality. If both conditions hold, natural selection might have favored genotypes with little or no awareness of their deceptive signaling. [26]
At the fourth level, deception includes recognition of other animals' beliefs, i.e., second-order thinking, as when a chimpanzee misleads other chimpanzees to prevent their discovering a food source. [3] This type of deception seems to be prevalent in humans, [3] but this level also corresponds to the realization of higher-order intentionality. [4] Tactical or functional deception is the use of signals or displays from an animal's normal repertoire to mislead or deceive another individual. [27]
Predation is a biological interaction where 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 and parasitoidism. It is distinct from scavenging on dead prey, though many predators also scavenge; it overlaps with herbivory, as seed predators and destructive frugivores are predators.
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 simplest case, as in Batesian mimicry, a mimic resembles a model, so as to deceive a dupe, all three being of different species. A Batesian mimic, such as a hoverfly, is harmless, while its model, such as a wasp, is harmful, and is avoided by the dupe, such as an insect-eating bird. Birds hunt by sight, so the mimicry in that case is visual, but in other cases mimicry may make use of any of the senses. Most types of mimicry, including Batesian, are deceptive, as the mimics are not harmful, but Müllerian mimicry, where different harmful species resemble each other, is honest, as when species of wasps and of bees all have genuinely aposematic warning coloration. More complex types may be bipolar, involving only two species, such as when the model and the dupe are the same; this occurs for example in aggressive mimicry, where a predator in wolf-in-sheep's-clothing style resembles its prey, allowing it to hunt undetected. Mimicry is not limited to animals; in Pouyannian mimicry, an orchid flower is the mimic, resembling a female bee, its model; the dupe is the male bee of the same species, which tries to copulate with the flower, enabling it to transfer pollen, so the mimicry is again bipolar. In automimicry, another bipolar system, model and mimic are the same, as when blue lycaenid butterflies have 'tails' or eyespots on their wings that mimic their own heads, misdirecting predator dupes to strike harmlessly. Many other types of mimicry exist.
Self-deception is a process of denying or rationalizing away the relevance, significance, or importance of opposing evidence and logical argument. Self-deception involves convincing oneself of a truth so that one does not reveal any self-knowledge of the deception.
Batesian mimicry is a form of mimicry where a harmless species has evolved to imitate the warning signals of a harmful species directed at a predator of them both. It is named after the English naturalist Henry Walter Bates, who worked on butterflies in the rainforests of Brazil.
Anti-predator adaptations are mechanisms developed through evolution that assist prey organisms in their constant struggle against predators. Throughout the animal kingdom, adaptations have evolved for every stage of this struggle, namely by avoiding detection, warding off attack, fighting back, or escaping when caught.
In animal communication, an alarm signal is an antipredator adaptation in the form of signals emitted by social animals in response to danger. Many primates and birds have elaborate alarm calls for warning conspecifics of approaching predators. For example, the alarm call of the blackbird is a familiar sound in many gardens. Other animals, like fish and insects, may use non-auditory signals, such as chemical messages. Visual signs such as the white tail flashes of many deer have been suggested as alarm signals; they are less likely to be received by conspecifics, so have tended to be treated as a signal to the predator instead.
Apparent death is a behavior in which animals take on the appearance of being dead. It is an immobile state most often triggered by a predatory attack and can be found in a wide range of animals from insects and crustaceans to mammals, birds, reptiles, amphibians, and fish. Apparent death is separate from the freezing behavior seen in some animals.
Müllerian mimicry is a natural phenomenon in which two or more well-defended species, often foul-tasting and sharing common predators, have come to mimic each other's honest warning signals, to their mutual benefit. The benefit to Müllerian mimics is that predators only need one unpleasant encounter with one member of a set of Müllerian mimics, and thereafter avoid all similar coloration, whether or not it belongs to the same species as the initial encounter. It is named after the German naturalist Fritz Müller, who first proposed the concept in 1878, supporting his theory with the first mathematical model of frequency-dependent selection, one of the first such models anywhere in biology.
Aposematism is the advertising by an animal, whether terrestrial or marine, to potential predators that it is not worth attacking or eating. This unprofitability may consist of any defenses which make the prey difficult to kill and eat, such as toxicity, venom, foul taste or smell, sharp spines, or aggressive nature. These advertising signals may take the form of conspicuous coloration, sounds, odours, or other perceivable characteristics. Aposematic signals are beneficial for both predator and prey, since both avoid potential harm.
An eyespot is an eye-like marking. They are found in butterflies, reptiles, cats, birds and fish.
Aggressive mimicry is a form of mimicry in which predators, parasites, or parasitoids share similar signals, using a harmless model, allowing them to avoid being correctly identified by their prey or host. Zoologists have repeatedly compared this strategy to a wolf in sheep's clothing. In its broadest sense, aggressive mimicry could include various types of exploitation, as when an orchid exploits a male insect by mimicking a sexually receptive female, but will here be restricted to forms of exploitation involving feeding. For example, indigenous Australians who dress up as and imitate kangaroos when hunting would not be considered aggressive mimics, nor would a human angler, though they are undoubtedly practising self-decoration camouflage. Treated separately is molecular mimicry, which shares some similarity; for instance a virus may mimic the molecular properties of its host, allowing it access to its cells. An alternative term, Peckhamian mimicry, has been suggested, but it is seldom used.
Animal colouration 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 has strong patterns, conspicuous colours and is iridescent, while the female is far less visible.
Emsleyan mimicry, also called Mertensian mimicry, describes an unusual type of mimicry where a deadly prey mimics a less dangerous species.
Distraction displays, also known as diversionary displays, or paratrepsis are anti-predator behaviors used to attract the attention of an enemy away from something, typically the nest or young, that is being protected by a parent. Distraction displays are sometimes classified more generically under "nest protection behaviors" along with aggressive displays such as mobbing. These displays have been studied most extensively in bird species, but also have been documented in populations of stickleback fish and in some mammal species.
Chemical mimicry is a type of biological mimicry involving the use of chemicals to dupe an operator.
Underwater camouflage is the set of methods of achieving crypsis—avoidance of observation—that allows otherwise visible aquatic organisms to remain unnoticed by other organisms such as predators or prey.
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.
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 deceptively encourage mutualists, like pollinators, to provide a service without offering a reward in return.
In evolutionary biology, mimicry in vertebrates is mimicry by a vertebrate of some model, deceiving some other animal, the dupe. Mimicry differs from camouflage as it is meant to be seen, while animals use camouflage to remain hidden. Visual, olfactory, auditory, biochemical, and behavioral modalities of mimicry have been documented in vertebrates.
Tactical deception in animals, also called functional deception, is the use by an animal of signals or displays from an animal's normal repertoire to mislead or deceive another individual.
it's quite deliberate and wholly guided by science.
Others rely on the technique adopted by a wolf in sheep's clothing—they mimic a harmless species. ... Other predators even mimic their prey's prey: angler fish (Lophiiformes) and alligator snapping turtles Macroclemys temmincki can wriggle fleshy outgrowths of their fins or tongues and attract small predatory fish close to their mouths.