Reappearance of specific colour patterns after nerve regeneration in Octopus

Abstract

In the octopus the capacity to regulate the patterns of colours and skin papillae on the back can recover after interruption of the pallial nerve by either crushing or cutting. About 40 to 60 days after denervation the spontaneous waves of colour due to hyperexcitability of the chromatophore muscles cease and the skin begins to change colour in phase with that of the intact side. Specific patches of colour recover in the precise positions they occupied before operation. Different patterns can then be produced after regeneration, as before, according to the behavioural situation and background. The experiments therefore indicate that nerve fibres had re-made their original connexions and the possible mechanisms for this are discussed. Recovery of the patterning was not always complete, sometimes it occurred only over part of the back, especially when the nerve had been sectioned.