Proecdysis, Setal Development, and Molt Prediction in the American Lobster (Homarus americanus)

Abstract

Setal development and proecdysial cuticular changes can be observed in the pleopods of the American lobster (Homarus americanus) from earliest D₀ through stage D₃, and with pleopod staging criteria it is possible to follow proecdysis from beginning to end. A technique is described for recognition of all stages and substages of proecdysis, for evaluating effects of various treatments on proecdysis, and for predicting time of ecdysis where holding temperature is known. Histological comparisons between the pleopods and the general integument suggest a universal criterion for stage D₂, and a need for adjustment in some accepted molt stage criteria. Development plateaus occur in stage D₀ instead of C₄ in this species, and this suggests that the concept of stage C anecdysis may be incorrect.