An analysis of color change phenomena in the leaf frog, Agalychnis dacnicolor

Abstract

AbstractIn vivo and in vitro studies of integumental color change in the leaf frog, Agalychnis dacnicolor, are reported. A color index is established for the assessment of color change in the absence of melanophore visibility. Green leaf frogs adapt rapidly to background by controlling MSH release. Some members of the population are always brown regardless of background. Naturally brown specimens respond to localized reductions in illumination by becoming green in the affected area. Either skin or chromatophores in these areas are photosensitive. Isolated skins darkened with theophylline are not photosensitive; however, masking of areas of isolated skins prevented darkening of the masked area. Contact between skin and mask may inhibit darkening by physically preventing melanosome dispersion. Neither melanosome aggregation nor dispersion occur in isolated skins incubated in oxygen‐free media. Experiments involving denervation and electrical stimulation both in vivo and in vitro fail to implicate a chromatophore control by innervation.