The survival and development of the shrimp Crangon crangon (L.), reared in the laboratory under non-circadian light-dark cycles

Abstract

The shrimp, Crangon crangon (L.), has been reared from hatching to the late juvenile phase, under a circadian (LD 12 : 12) and two non-circadian (LD 8 : 8 and LD random) light-dark cycles. During the zoeal phase, survival in the non-circadian regimes was markedly lower than in the control circadian treatments. This effect supports the hypothesis that the entraining influence of daily environmental cycles is important in coordinating the various physiological processes within the animal. There was no evidence, however, that growth and morphological development were affected in the non-circadian regimes.