Observations sur la pigmentation et la physiologie chromatique de Periclimenes amethysteus (Crustacea, Caridea)

Abstract

The Mediterranean prawn Periclimenes amethysteus bears various characteristic color patches that fluctuate according to age, adults being more colorful than juveniles. Several pigments are present: a white yellowish one located in the chromatophores, a violet pigment diffuse in the epidermis, and a rare red–garnet one. Pink patches seem to result partly from the mixture of the white and violet pigments. There is no physiological chromatic adaptation to background color. However, the white pigment is completely dispersed during the day and retracted at night; the violet pigment vanishes at night. Thus the animal that is brightly colored in daylight becomes almost transparent at night. Eyestalk ablation produces retraction of the white pigment, a slight enhancement of violet pigmentation and a dispersion of the red pigment. Erythrophores and leucophores do not present direct photosensibility and seem to be only hormonally controlled. Color changes in this species are very different from those previously described in other Palaemonidae.