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Predator
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 (which usually do not kill the host) and parasitoidism (which always does, eventually). 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. Predators may actively search for or pursue prey or wait for it, often concealed. When prey is detected, the predator assesses whether to attack it. This may involve ambush or pursuit predation, sometimes after stalking the prey. If the attack is successful, the predator kills the prey, removes any inedible parts like the shell or spines, and eats it. Predators are adapted and often highly specialized for hunting, with acute senses such as vision, hearing, or smell. Many predatory animals, both vertebrate an ...
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Antipredator Adaptation
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. The first line of defence consists in avoiding detection, through mechanisms such as camouflage, masquerade, apostatic selection, living underground, or nocturnality. Alternatively, prey animals may ward off attack, whether by advertising the presence of strong defences in aposematism, by mimicking animals which do possess such defences, by startling the attacker, by signalling to the predator that pursuit is not worthwhile, by distraction, by using defensive structures such as spines, and by living in a group. Members of groups are at reduced risk of predation, despite the increased conspicuousness of a group, through improved vigilance, predator confusio ...
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Pursuit Predation
Pursuit predation is a form of predation in which predators actively give chase to their prey, either solitarily or as a group. It is an alternate predation strategy to ambush predation — pursuit predators rely on superior speed, endurance and/or teamwork to seize the prey, while ambush predators use stealth, luring, the use of surroundings and the element of surprise to capture the prey. While the two patterns of predation are not mutually exclusive, morphological differences in an organism's body plan can create an evolutionary bias favoring either type of predation. Pursuit predation is typically observed in carnivorous species within the kingdom Animalia, such as cheetahs, lions, wolves and early ''Homo'' species. The chase can be initiated either by the predator, or by the prey if it is alerted to a predator's presence and attempt to flee before the predator gets close. The chase ends either when the predator successfully catches up and tackles the prey, or when ...
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Alarm Call
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. Different calls may be used for predators on the ground or from the air. Often, the animals can tell which member of the group is making the call, so that they can disregard those of little reliability. Evidently, alarm signals promote survival by allowing the receivers of the alarm to escape from the source of peril; this can evolve by kin selectio ...
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Biological Interaction
In ecology, a biological interaction is the effect that a pair of organisms living together in a community have on each other. They can be either of the same species (intraspecific interactions), or of different species (interspecific interactions). These effects may be short-term, like pollination and predation, or long-term; both often strongly influence the evolution of the species involved. A long-term interaction is called a symbiosis. Symbioses range from mutualism, beneficial to both partners, to competition, harmful to both partners. Interactions can be indirect, through intermediaries such as shared resources or common enemies. This type of relationship can be shown by net effect based on individual effects on both organisms arising out of relationship. Several recent studies have suggested non-trophic species interactions such as habitat modification and mutualisms can be important determinants of food web structures. However, it remains unclear whether these findings g ...
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Evolutionary Arms Race
In evolutionary biology, an evolutionary arms race is an ongoing struggle between competing sets of co-evolving genes, phenotypic and behavioral traits that develop escalating adaptations and counter-adaptations against each other, resembling an arms race. These are often described as examples of positive feedback.Dawkins, R. 1996. '' The Blind Watchmaker'' New York: W. W. Norton. Note: This book was also published by Penguin in 1991. While the text is identical, page numbers differ The co-evolving gene sets may be in different species, as in an evolutionary arms race between a predator species and its prey (Vermeij, 1987), or a parasite and its host. Alternatively, the arms race may be between members of the same species, as in the manipulation/sales resistance model of communication (Dawkins & Krebs, 1979) or as in runaway evolution or Red Queen effects. One example of an evolutionary arms race is in sexual conflict between the sexes, often described with the term Fisher ...
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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. Often, mimicry functions to protect a species from predators, making it an anti-predator adaptation. Mimicry evolves if a receiver (such as a predator) perceives the similarity between a mimic (the organism that has a resemblance) and a model (the organism it resembles) and as a result changes its behaviour in a way that provides a selective advantage to the mimic. The resemblances that evolve in mimicry can be visual, acoustic, chemical, tactile, or electric, or combinations of these sensory modalities. Mimicry may be to the advantage of both organisms that share a resemblance, in which case it is a form of mutualism; or mimicry can be to the detriment of one, making it parasitic or competitive. The evolutionary convergence between groups is driven by ...
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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 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, as well as making general aiming easier. 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 the open ocean, where there is no background, the principal methods of camouflage are transparency, silvering, and countershading, while the bioluminescence, ability to produce light is among other things used for counter-illumination on the undersides of cephalopods such as squid. Some animals, such as chamel ...
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Warning Coloration
Aposematism is the advertising by an animal to potential predators that it is not worth attacking or eating. This unprofitability may consist of any defences 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. The term was coined in 1877 by Edward Bagnall Poulton for Alfred Russel Wallace's concept of warning coloration. Aposematism is exploited in Müllerian mimicry, where species with strong defences evolve to resemble one another. By mimicking similarly coloured species, the warning signal to predators is shared, causing them to learn more quickly at less of a cost. A genuine aposematic signal that a species actually possesses chemical or physical defences is not the only way ...
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Ambush Predation
Ambush predators or sit-and-wait predators are carnivorous animals that capture or trap prey via stealth, luring or by (typically instinctive) strategies utilizing an element of surprise. Unlike pursuit predators, who chase to capture prey using sheer speed or endurance, ambush predators avoid fatigue by staying in concealment, waiting patiently for the prey to get near, before launching a sudden overwhelming attack that quickly incapacitates and captures the prey. The ambush is often opportunistic, and may be set by hiding in a burrow, by camouflage, by aggressive mimicry, or by the use of a trap (e.g. a web). The predator then uses a combination of senses to detect and assess the prey, and to time the strike. Nocturnal ambush predators such as cats and snakes have vertical slit pupils helping them to judge the distance to prey in dim light. Different ambush predators use a variety of means to capture their prey, from the long sticky tongues of chameleons to the expa ...
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Parasitoid
In evolutionary ecology, a parasitoid is an organism that lives in close association with its host (biology), host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionarily stable strategy, evolutionary strategies within parasitism, distinguished by the fatal prognosis for the host, which makes the strategy close to predation. Among parasitoids, strategies range from living inside the host (''endoparasitism''), allowing it to continue growing before emerging as an adult, to Paralysis, paralysing the host and living outside it (''ectoparasitism''). Hosts can include other parasitoids, resulting in hyperparasitism; in the case of oak galls, up to five levels of parasitism are possible. Some parasitoids Behavior-altering parasite, influence their host's behaviour in ways that favour the propagation of the parasitoid. Parasitoids are found in a variety of Taxon, taxa across the insect superorder Endopterygota, whose compl ...
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Polar Bear (Ursus Maritimus) With Its Prey
The polar bear (''Ursus maritimus'') is a hypercarnivorous bear whose native range lies largely within the Arctic Circle, encompassing the Arctic Ocean, its surrounding seas and surrounding land masses. It is the largest extant bear species, as well as the largest extant land carnivore. A boar (adult male) weighs around , while a sow (adult female) is about half that size. Although it is the sister species of the brown bear, it has evolved to occupy a narrower ecological niche, with many body characteristics adapted for cold temperatures, for moving across snow, ice and open water, and for hunting seals, which make up most of its diet. Although most polar bears are born on land, they spend most of their time on the sea ice. Their scientific name means " maritime bear" and derives from this fact. Polar bears hunt their preferred food of seals from the edge of sea ice, often living off fat reserves when no sea ice is present. Because of their dependence on the sea ice, po ...
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Claw
A claw is a curved, pointed appendage found at the end of a toe or finger in most amniotes (mammals, reptiles, birds). Some invertebrates such as beetles and spiders have somewhat similar fine, hooked structures at the end of the leg or tarsus for gripping a surface as they walk. The pincers of crabs, lobsters and scorpions, more formally known as their chelae, are sometimes called claws. A true claw is made of a hard protein called keratin. Claws are used to catch and hold prey in carnivorous mammals such as cats and dogs, but may also be used for such purposes as digging, climbing trees, self-defense and grooming, in those and other species. Similar appendages that are flat and do not come to a sharp point are called nails instead. Claw-like projections that do not form at the end of digits but spring from other parts of the foot are properly named spurs. Tetrapods In tetrapods, claws are made of keratin and consist of two layers. The unguis is the harder external layer, ...
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