Mechanisms of Resorption and Deposition of Calcium in the Carapace of the Crab Carcinus Maenas

Premoult resorption of Ca from the carapace of Carcinus involves the active inward transport of Ca by the hypodermis with maximal rates occurring in stage D2 of the moult cycle. Postmoult calcification of the carapace involves the active outward transport of Ca by the hypodermis with maximal rates occurring in stages A1 and A2 of the moult cycle. Bidirectional active transport of Ca by Carcinus hypodermis may be accomplished by means of a quercitin-sensitive Ca-ATPase and a Na/Ca exchange mechanism in conjunction with observed changes in epithelial cell shape and size.