Functions of The Wing Pattern
The underwing pattern is highly cryptic. It is conceivable that the eye pattern is a generalized form of mimicry. It is known that many small animals hesitate to go near patterns resembling eyes with a light-colored iris and a large pupil, which matches the appearance of the eyes of many predators that hunt by sight. The main predators of Caligo are apparently small lizards such as Anolis.
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Anolis carolinensis
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Caligo
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Hyla arborea
According to the Batesian mimicry theory the pattern on the wings of Caligo resemble the head of a predator like a lizard or an amphibian. It should deter predators while resting, feeding, mating, or emerging from the pupa.
The role of eyespots as antipredator mechanisms has been discussed since the 19th century. Several hypotheses are suggested to explain their occurrence. In some butterflies, particularly Satyrinae (such as the Gatekeeper Butterfly and the Grayling), it has been shown that ocelli serve as a decoy, diverting bird attack away from the vulnerable body, and towards the outer part of the hindwings or the forewing tip.
Research of Stevens et al. (2008), however, suggests that eye-spots are not a form of mimicry and do not deter predators because they look like eyes. Rather the conspicuous contrast in the patterns on the wings deter predators. In this study, however, the influence of surrounding forms, like the head region of a predator, was not tested. Also the question why animals evolved such complex imitations of other species is left unanswered.
Read more about this topic: Owl Butterfly
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