THE ROLE OF THE PINEAL COMPLEX AND LATERAL EYES IN THE COLOUR CHANGE RESPONSE OF THE DOGFISH, SCYLIORHINUS CANICULA L.

Abstract

SUMMARY The effects of black and white illuminated backgrounds, and darkness, on the colour-change responses of intact, blinded and pinealectomized Scyliorhinus canicula were investigated. Blinding caused an immediate darkening response followed by a gradual paling, the background responses being absent, while darkness produced a further slight paling in blinded fish indicating a non-visual response. Pinealectomy did not affect the background responses but the normal paling response in darkness was abolished and the fish darkened. The latter result demonstrates a paling mechanism, mediated by the pineal, the interaction of which with the known inhibitory control system for melanophore-stimulating hormone release allows an interpretation of the chromatic responses.