Timing of the metamorphic molt of the American lobster (Homarus americanus) is governed by a population-based, photoperiodically entrained daily rhythm

• Published in: Canadian journal of fisheries and aquatic sciences Vol. 56; no. 12; pp. 2324 - 2330
• Main Authors: Waddy, S L, Aiken, D
• Format: Journal Article
• Language: English
• Published: 01.12.1999
• Subjects: Homarus americanus; Marine; ANW, Canada, New Brunswick, Passamaquoddy Bay
• ISSN: 0706-652X; 1205-7533
• DOI: 10.1139/cjfas-56-12-2324

The metamorphic molt of the American lobster (Homarus americanus) occurs in the form of a population-based, recurring daily rhythm that is photoperiodically entrained. Molting occurs predominantly in the scotophase (dark period) at temperatures of 11, 15, and 20 degree C and in both normal and reversed photoperiod cycles. Molting is arrhythmic in larvae reared in continuous illumination (LL), but when larvae reared in LL are transferred to cyclic photoperiod conditions (LD 12:12), the rhythm is reinstated in a stepwise manner over 3 days. When larvae are transferred from the onset of darkness: similar proportions of larvae (79-89%) reared in scotophase lengths of 6, 10, and 12 h molted in the 12-h period following lights-off. The results demonstrate that the synchrony of the metamorphic molt with the scotophase is not fortuitous and suggest that the molting rhythm may result from a gated event under the influence of an endogenous pacemaker.