The chromatic biology of flatfish (pleuronectidae)

Abstract

Most flatfish have a white lower blind side and a brown or grey upper ocular side which can display cryptic patterning with dark areas and white spots. Active predatory flatfish like Reinbardtius hippoglossoides have complete ambicoloration and this can also occur partly or completely in other flatfish such as Pleuronectes americanus. Both hypermelanosis and hypomelanosis can occur in aquacultured flatfish. Dermal and epidermal melanophores, xanthophores and iridophores occur in various flatfish species and patterning has a morphological basis with differences in the size and frequency of chromatophores. The patterning is also physiological displaying differential responsiveness to background and stress. In Pleuronectes americanus chromatic decentralization and hypophysectomy demonstrate that the pattern-related responsiveness of melanophores is neurally controlled and that xanthophores are regulated by the pituitary. In vitro pharmacology indicates that α-adrenoceptors mediate melansome aggregation and β2-adrenoceptors mediate dispersion. There is a pattern-related differential balance in a and β-adrenoceptor sensitivity but experiments after chemical sympathectomy suggest the additional participation of modulatory factors. © 1998 Taylor & Francis Group, LLC.