ONTOGENY OF CHANGES IN VOLUME OF VISCERAL CAVITY AND BRANCHIAL CHAMBERS OF FEMALE ROCK CRABS, CANCER IRRORATUS SAY, 1817; POTENTIAL CONSEQUENCES

Shape change associated with growth in Crustacea is referred to as relative, or allometric growth. Such changes may occur gradually over a series of molts, or they may occur abruptly at a single molt, such as that between the final immature and first mature instar. Morphometrics have been used to determine size of sexual maturity of several populations of the rock crab, Cancer irroratus Say, 1817. This paper describes the relative growth of the visceral cavity and branchial chambers of female Cancer irroratus in relation to linear body dimensions and weight. The principal sample consisted of 29 female specimens of Cancer irroratus, collected in the Gulf of Maine in 1990. While it appears that the respiratory exchange surface appears to diminish with size of the individual, it is clear that other physiological mechanisms exist that compensate adequately for the apparent loss.