Abstract

Calcium (Ca) concentrations were determined in the hemolymph of the crayfish at different stages of the molting cycle. The molting cycle was divided into eight stages: ecdysis (E=O), early postmolt (A=l), late postmolt (B=2), early intermolt (C1_Z=3), mid intermolt (CZ-3= 3 .5 ), late intermolt (C3_4=4), early premolt (DO_Z=S), and late premoIt (D3_ 4=6). A relationship was observed between the hemolymph Ca and the molting stage (P<0.001). Hemolymph Ca in intermolt stage 4 crayfish ranged from 8.1 to 11.9 mM with a mean of 10.4 mM. Hemolymph Ca was 35% higher in stage 6 crayfish than in stage 4 crayfish. Within stage 3 through 6, the mean hemolymph Ca could be precisely estimated from the equation: Ca, mg / 100 m1 = 14 + 7x (molting stage). There was a direct relationship between hemolymph Ca concentration and carapace length at stage 6 (P<0.05). At ecdysis no differences were found in the size and Ca content of the left and right gastroliths. Carapace lost about 20% of its calcium prior to ecdysis, an amount far in excess of that stored in the gastrolith. In addition, during calcification, the exoskeleton required about 30 times the Ca available from the gastrolith. Therefore the gastrolith can not serve as the primary source of exoskeletal calcium. The gastrolith may be most important in the regulation of hemolymph Ca during postmolt when the soft exoskeleton is highly permeable to water influx.

Supplemental Documents

• There are no supplementary documents for this article

Cited By

Citations: