Relation of Colour Change to Moulting in Prawns

Abstract

STUDIES of crustacean hormones have heretofore been concentrated either on chromatophorotropic actions, or upon effects on moulting and related metabolic phenomena. We have now obtained evidence that, in Leander serratus (Pennant), the chromatophorotropic hormones are also concerned in the intermoult cycle. Numerous previous studies have shown that eyestalk removal accelerates moulting in many species of crustaceans, including L. serratus ¹. We found that, in a series of 114 eyestalkless animals, only two moulted, while of 146 normal animals kept under identical conditions, twelve moulted. This difference is statistically significant at the 5 per cent level of probability. We are unable to account for the difference from Drach's results¹; but Carlisle (personal communication) has suggested that there are important racial differences between prawns of the same species at Naples, Roscoff and Plymouth. Analysis of the effect of removal of eyestalk showed that it could be attributed to an increase in length of stage D ₂ of the intermoult cycle², during which the old integument is undergoing resorption, and the new integument is being formed, and to an increased mortality immediately preceding the moult in eyestalkless specimens.