Eyespot (mimicry)

An eyespot (sometimes ocellus) is an eye-like marking. They are found in butterflies, reptiles, cats, birds and fish.

Eyespots may be a form of mimicry in which a spot on the body of an animal resembles an eye of a different animal to deceive potential predator or prey species; a form of self-mimicry, to draw a predator's attention away from the most vulnerable body parts; or to appear as an inedible or dangerous animal. In larger animals, eyespots may play a role in intraspecies communication or courtship – the most well-known example is probably the eyespots on a peacock's display feathers. Eyespots are not necessarily adaptations, but may in some cases be spandrels, accidental artefacts of pattern formation.

The morphogenesis of eyespots is controlled by a small number of genes active in development of a wide range of animals, including Engrailed, Distal-less, Hedgehog, and the Notch signaling pathway.

The eye-like markings in some butterflies and moths, like the Bicyclus anynana, and certain other insects, as well as the Sunbittern (a bird) do not seem to serve only a mimicry function. In some other cases, the evolutionary function of such spots is also not understood. There is evidence that eyespots in butterflies are antipredator adaptations, either in deimatic displays to distract, startle or scare off predators, or to deflect attacks away from vital body parts. Butterfly eyespots may also play a role in mate recognition and sexual selection.

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