Observations on the moulting behaviour of the spiny lobster Panulirus homarus (Linnaeus)

Abstract

The moulting process of the spiny lobster Panulirus homarus in the laboratory was observed and described. In this speceis, a lobster approaching ecdysis can be identified, almost 48 hours before, by the presence of a longitudinal decalcified resorptive line along the branchiostegites. Under normal conditions, the lobster completes ecdysis within 8-10 hours after the initiation of the moulting process. The active phase of ecdysis is completed within 3- 4 minutes. Initially, the lobster withdraws the thorax gradually from the old exoskeleton and finally sheds the abdominal part of it by strong flapping of the tail. The lobster moulting on a rough substratum completes ecdysis in the upright position, whereas those moulting on a soft substratum rolls on to one side while withdrawing the walking legs. The newly moulted lobster regains mobility within a few seconds and avoids contact with other lobsters until the new exoskeleton is sufficiently hardened.