Reversal of Handedness, Growth, and Claw Stridulatory Patterns in the Stone Crab Menippe Mercenaria (Say) (Crustacea: Xanthidae)

Abstract

ABSTRACT All 103 stone crabs reared from eggs of one left-handed and two right-handed female crabs were initially right-handed (side bearing crusher claw), but 88% of laboratory-reared juveniles whose crushers were removed reversed handedness on the first regenerative molt. Eight of 12 (67%) feral adult or pre-adult crabs reversed handedness on third or fourth molt following crusher loss, but only 5% (1 of 19) and 6% (1 of 16) reversed on the first and second molts, respectively. Reversal of handedness following claw loss by young juveniles is the most likely cause of the change from 100% initial right-handedness to 80% among older juveniles and sublegal (carapace width < 80 mm) adults in natural populations. The ratio is not altered in fished populations, probably because natural death occurs before most legal crabs can complete the number of molts (3 or more) required for adult claw reversal. No adult crab regained a normal stridulatory pattern on a regenerated claw, even after five postregenerative molts. Therefore, most, if not all, claws regenerated following initial claw harvest by the fishery should be recognizable as such in subsequent landings. Growth averaged 20% carapace width increase per molt for 94 laboratory molts of adult crabs; this was comparable to field growth increments in other studies.