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Species of the Week
Rhacophorus nigropalmatus | Wallace's Flying Frog

Photo © Peter Janzen

Amphibian News
Carotenoids are pigments produced primarily by plants. Animals ingest carotenoids to use in a variety of important ways, especially in producing or modifying coloration. For example in birds, they are the basis of the red pigmentation in the plumage of breeding male house finches and crossbills. Stückler et al. (2022) investigated the role of carotenoids in modulating coloration in Wallace's Flying Frog, Rhacophorus nigropalmatus. This frog exhibits a dramatic ontogenetic shift in coloration from bright red in recently metamorphosed juveniles, to green and brown with extensive white spotting in older juveniles, to vivid green with black and yellow webbing and yellow flanks in adults. In controlled experiments, they showed that dietary carotenoid supplementation was necessary for this species to achieve its natural vivid green adult coloration. Individuals without a source of dietary carotenoids, or reduced carotenoid intake, were blue-green in color. Furthermore, R. nigropalmatus was capable of extensive rapid color changes associated with either the stress of handling or the light regime experienced by the individual frog – but only if they had sufficient carotenoids in the diet. This study broke a lot of new ground, including that the dull adult pigmentation resulting from lack of sufficient carotenoids in early life is apparently not correctible later in life with enhanced carotenoid intake. Given the likely importance of baseline coloration and dynamic color change for crypsis and sexual selection, dietary carotenoids are likely critical to R. nigropalmatus – and this likely applies to many additional species of frogs as well.

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Current number of amphibian species: 8,488 (Aug 17, 2022) Newly added species