Aposematism


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Related to Aposematism: Voltinism, Mullerian mimicry

Aposematism

 

(also warning coloration and form), one of the types of protective coloration and form in animals. Aposematic coloration, which contrasts with the animal’s background, is demonstrated suddenly in response to danger and is usually combined with a threatening pose and sounds.

The back wings of certain moths of the family Sphingidae and the genus Noctuidae, as well as cicadas, locusts, and mantises, have eyelike spots or bright bands. Normally these insects are not noticeable, owing to cryptic coloration. When an enemy approaches, however, they open their back wings and unexpectedly reveal their bright coloring, which frightens off the predator. Caterpillars of the family Sphingidae assume a threatening pose, raising the front portion of the body slightly and inflating the thorax, on which eyelike spots protrude in some species. Octopuses, agamas, and chameleons assume a threatening pose and acquire vivid coloration; many reptiles also hiss. The death’s-head moth emits a sharp squeak by releasing air from its foregut.

Aposematism protects animals from predators and gives them an advantage in the struggle for life.

I. KH. SHAROVA

References in periodicals archive ?
about low-quality food yet again implies aposematism. This new
Moreover, as in other cases of aposematism (Cott, 1940; Wickler, 1968;
Ontogenetic colour change and the evolution of aposematism: a case study in panic moth caterpillars.
Radclyffe Roberts (Roberts & Carbonell 1982): "One of us (H.R.R.) recently observed 20 to 30 conspicuous nymphs on top of a tussock of grass two or three meters from a small solanaceous shrub stripped of its leaves, which suggests that the gregarious behavior is a part of the premonitory defense." In well-studied species such as Schistocerca emarginata, gregariousness and aposematism are related to the feeding of nymphs on plants that confer gut-content mediated toxicity to predators (Sword et al.2000).
Mimetism must not be confused with aposematism as a whole, as descibed above.
Edmunds (1991) argued that one or both types of mimicry frequently occur in similarly colored nudibranch species, suggesting that this seems to be the strongest support for aposematism in this group of molluscs, because the widespread occurrence of mimicry in those species is almost impossible to explain unless some of them are aposematic.
Rosenberg (1989) argued that aposematism in marine gastropods cannot evolve by kin selection because they have pelagic larvae and thus disperse randomly over wide areas, minimizing the probability that kin settle close to each other.
This ensemble of traits has been named the Chemical Defense Syndrome (CDS), and includes chemical defense, visual, chemical, and/or mechanical (tactile or auditory) warning signals (aposematism) and threat displays, aggregation, exposed diurnal behavior, flightlessness, sluggishness, and large size (Whitman et al.
The energetic hydromechanical signal also may frighten predators because of the apparent large size and strength, a form of aposematism. It also may act as a decoy, since the source is distant from the signal.
In the study, aposematism was used as a cue for unpalatability, and the result is in accordance with the expectation that in insects gregariousness should evolve in unpalatable species (Sillen-Tullberg and Leimar 1988).
- Aposematism, conventional signalling theory, frequency-dependence, handicap signalling theory, honesty, mimicry, unpalatable prey, warning coloration.
- Adaptive coloration, antipredator mechanisms, aposematism, elapid snakes, mimicry, vertebrates.