VARIABILITY IN LARVAL STAGES OF THE BLUE CRAB, CALLINECTES SAPIDUS,

Abstract

The larvae of the blue crab, Callinectes sapidus Rathbun, were maintained individually under laboratory conditions to determine if variability occurred in the number of stages or in the morphological characteristics normally associated with each stage. Through an examination of the exuviae and the larvae, 3 types of variability were observed: (1), molting without any perceptible morphological changes; (2), the elimination or "skipping" of a larval stage previously described; and (3), a molt which resulted in a larva with a combination of morphological previously described for 2 separate larval stages. Variability, observed in from 40 to 63% of the 3 series of larvae studied, did not occur prior to the 5th zoeal stage. The significance of variability during late stages of development and the evidence for independence of molting and growth mechanisms is discussed. The hypothesis is presented that the 3 types of variability which were observed are due to the stability of the endocrine mechanisms controlling larval ecdysis while the independent mechanisms which control development are either retarded or accelerated.