The bright colours of this Yellow-winged Darter dragonfly serve as a warning to predators of its noxious taste.

Aposematism (from apo- away, and sematic warning), is a means of natural defense employing conspicuous colours, sounds, or other methods by which an organism openly projects a warning signal to potential predators. The intent to become as noticeable as possible is the antithesis of the principles of natural camouflage. Image File history File links Download high resolution version (2567x1574, 603 KB) Yellow-winged Darter This image shows an about 1. ... Image File history File links Download high resolution version (2567x1574, 603 KB) Yellow-winged Darter This image shows an about 1. ... Binomial name Sympetrum flaveolum (Linnaeus, 1758) The Yellow-winged Darter, Sympetrum flaveolum, is a European dragonfly. ... A crab is an example of an organism. ... This snapping turtle is trying to make a meal of a Canada goose, but the goose is too wary. ... Antithesis (Greek for setting opposite, from against + position) means a direct contrast or exact opposition to something. ... Anolis caroliensis showing blending camouflage and counter-shading A flounder blends in with its environment. ...

Defense mechanism

Aposematism is a secondary defense mechanism—the organism's primary means of defense may be either:

Unpalatability

such as from the bitter taste arising from some insects such as the ladybird or tiger moth, or the noxious odour produced by the skunk, or:

Danger 

such as the poison glands of the poison dart frog, the sting of a velvet ant or neurotoxin in a black widow spider.

In these particular examples, the organism advertises its capabilities via either bright colouration in the case of the ladybird, poison frog and spider or by conspicuous stripes in the case of the skunk. Various types of tiger moth advertise their unpalatability by either producing ultrasonic noises which warn bats to avoid them, or by warning postures which expose brightly-colored body parts.Velvet ants have both bright colours and produce audible noises when grabbed (via stridulation), which serve to reinforce the warning. Orders See taxonomy Insects are invertebrates that are taxonomically referred to as the class Insecta. ... Subfamilies Chilocorinae Coccidulinae Coccinellinae Epilachninae Scymininae Sticholotidinae etc. ... Diversity  ? genera 11,000 species Type Species Arctia caja (Garden Tiger Moth) Subfamilies Arctiinae Ctenuchinae Lithosiinae Pericopinae Syntominae Arctiidae is a large and diverse family of moths with around 11,000 species found all over the world, with 6000 Neotropical species (Scoble 1995). ... Genera Conepatus Mydaus Mephitis Spilogale Skunks are moderately small mammals, usually with black-and-white fur, belonging to the family Mephitidae and to the order Carnivora. ... Distribution of Dendrobatidae (in black) Genera Proposed Subfamily Colostethinae proposed genus Ameerega Colostethus Epipedobates proposed genus Silverstoneia Proposed Subfamily Hyloxalinae Proposed genus Hyloxalus Proposed Subfamily Dendrobatinae Proposed genus Adelphobates Dendrobates Minyobates Proposed genus Oophaga Phyllobates Proposed genus Ranitomeya Proposed obsolete (invalid) Dendrobatidae genera: Cryptophyllobates Nephelobates The poison dart frog, poison... It has been suggested that sting (biology) be merged into this article or section. ... Mutillidae or velvet ants, also known as cow killers, are not actually ants but a type of wasp. ... It has been suggested that Neurotoxicity be merged into this article or section. ... black widow spider (Latrodectus mactans), a poisonous spider that is infamous for the females habit of eating the male after sexual intercourse. ... Ultrasound is sound with a frequency greater than the upper limit of human hearing, approximately 20 kilohertz. ... Stridulation is the production of sounds by rubbing two parts of the body together; this mechanism is best known in crickets, grasshoppers, and cicadas. ...

Prevalence

Aposematism is widespread in invertebrates, particularly insects, but less so in vertebrates, being mostly confined to a smaller number of reptile, amphibian and fish species. Some plants, such as Polygonum sagittatum, a species of knotweed, are thought to employ aposematism to warn herbivores of chemical (such as unpalatability) or physical defences (such as prickled leaves or thorns). Invertebrate is a term coined by Jean-Baptiste Lamarck to describe any animal without a spinal column. ... Classes and Clades See below Vertebrates are members of the subphylum Vertebrata (within the phylum Chordata), specifically, those chordates with backbones or spinal columns. ... Subclasses Anapsida Diapsida Reptiles are tetrapods and amniotes, animals whose embryos are surrounded by an amniotic membrane. ... Subclasses and Orders Order Temnospondyli - extinct Subclass Lepospondyli - extinct Subclass Lissamphibia   Anura   Caudata   Gymnophiona Amphibians (class Amphibia; from Greek αμφις both and βιος life) are a taxon of animals that include all tetrapods and four-legged vertebrates that do not have amniotic eggs, are ectotherms, and generally spend part of their time... A giant grouper at the Georgia Aquarium Fish are aquatic vertebrates that are typically cold-blooded; covered with scales, and equipped with two sets of paired fins and several unpaired fins. ... For other uses, see Plant (disambiguation). ... Species see text Polygonum cuspidatum fall foliage Polygonum, or knotweed, is a genus in the buckwheat family Polygonaceae. ... In zoology, an herbivore is an animal that is adapted to eat primarily plants (rather than meat). ...

The defence mechanism relies on the memory of the would-be predator; a bird that has once tried to eat a foul-tasting grasshopper will endeavour to avoid a repetition of the experience. Aposematism tends therefore to be confined to species that are attempting to defend themselves from predation by advanced species. Families Superfamily: Tridactyloidea Cylindrachaetidae Ripipterygidae Tridactylidae Superfamily: Tetrigoidea Tetrigidae Superfamily: Eumastacoidea Chorotypidae Episactidae Eumastacidae Euschmidtiidae Mastacideidae Morabidae Proscopiidae Thericleidae Superfamily: Pneumoroidea Pneumoridae Superfamily: Pyrgomorphoidea Pyrgomorphidae Superfamily: Acridoidea Acrididae Charilaidae Dericorythidae Lathiceridae Lentulidae Lithidiidae Ommexechidae Pamphagidae Pyrgacrididae Romaleidae Tristiridae Superfamily: Tanaoceroidea Tanaoceridae Superfamily: Trigonopterygoidea Trigonopterygidae Xyronotidae Grasshoppers are herbivorous insects of...

Origins of the theory

Alfred Russel Wallace, in response to an 1866 letter from Charles Darwin, was the first to suggest that aposematism could be an evolutionary mechanism. Darwin had proposed that conspicuous colouring could be explained in many species by means of sexual selection practices, but had realised that this could not explain the bright colouring of some species of caterpillar since they were not sexually active. Wallace responded with the suggestion that as the contrasting coloured bands of a hornet warned of its defensive sting, so could the bright colours of the caterpillar warn of its unpalatability. Alfred Russel Wallace Alfred Russel Wallace, OM, FRS (January 8, 1823 – November 7, 1913) was a British naturalist, explorer, geographer, anthropologist and biologist. ... Charles Robert Darwin FRS (12 February 1809 – 19 April 1882) was an English naturalist [1] who achieved lasting fame by producing considerable evidence that species originated through evolutionary change, at the same time proposing the scientific theory that natural selection is the mechanism by which such change occurs. ... Illustration from The Descent of Man and Selection in Relation to Sex by Charles Darwin showing the Tufted Coquette Lophornis ornatus, female on left, ornamented male on right. ... For the insect known colloquially in America as a hornet see Bald-faced hornet. ...

Aposematic mimicry

A harmless red milk snake mimics the bright colours of the poisonous coral snake

Aposematism is a sufficiently successful strategy that other organisms lacking the primary defence means will attempt to mimic the conspicuous markings of their genuinely aposematic counterparts. For example, the Aegeria moth is a mimic of the yellowjacket wasp, because it resembles the wasp, but is not capable of stinging. A predator who would thus avoid the wasp would similarly avoid the Aegeria. This form of mimicry, where the mimic lacks the defensive capabilities of its 'model', is known as Batesian mimicry, after Henry Walter Bates, a British naturalist who studied Amazonian butterflies in the second half of the nineteenth century. Image File history File links Red_milk_snake. ... Image File history File links Red_milk_snake. ... Binomial name Lampropeltis triangulum LaCépède, 1789 The milk snake (Lampropeltis triangulum) is a species of king snake. ... Species Over 65, see article. ... A mimic is any species that has evolved to appear similar to another successful species in order to dupe predators into avoiding the mimic, or dupe prey into approaching the mimic. ... Henry Walter Bates (February 8, 1825 - February 16, 1892) was an English naturalist and explorer. ...

Batesian mimicry finds greatest success when the ratio of mimic to mimicked is low; otherwise predators learn to recognise the imposters. Batesian mimics are known to adapt their mimicry to match the prevalence of aposematic organisms in their environment.

A second form of aposematism mimicry occurs when two organisms share the same anti-predation defence and mimic each other, to the benefit of both species. This form of mimicry is known as Müllerian mimicry, after Fritz Müller, a German naturalist who studied the phenomenon in the Amazonian in the late nineteenth century. For example, a yellowjacket wasp and a honeybee are Müllerian mimics; their similar coloring teaches predators that a striped pattern is the pattern of a stinging insect. Therefore, a predator who has come into contact with either a wasp or a honeybee will likely avoid both in the future. Fritz Müller Johann Friedrich Theodor Müller (March 31, 1821–May 21, 1897) was a German biologist who emigrated to Brazil, where he studied the natural history of the Amazon Rainforest and was an early advocate of evolutionary theory. ... The Amazon Basin is the part of South America drained by the Amazon River and its tributaries. ...

A poisonous coral snake

Image File history File links Micrurus_tener. ... Image File history File links Micrurus_tener. ... Species Over 65, see article. ...

References

• The arts of Deception and Camouflage, Mongabay.com
• The Functionality and Evolution of Aposematic Coloration, Sterling, T.

• Komarek, S. (1998). Mimicry, Aposematism and Related Phenomena in Animals & Plants. Vesmir. ISBN 80-85977-15-X.

• Rubino, D. & McCarthy, B. (2004). "Presence of aposematic (warning) coloration in vascular plants of southeastern Ohio". Journal of the Torrey Botanical Society 131(3): 252–256.