Calcium Regulation in the Freshwater Crayfish Austropotamobius Pallipes (Lereboullet) I. Calcium Balance in the Intermoult Animal

Calcium regulation in normal and in calcium-depleted specimens of Austro-potamobius pallipes in the intermoult condition has been investigated. Calcium turnover was very low and the normal calcium balance was negative for much of the winter intermoult stage. Calcium uptake was against a small electrochemical gradient, at least part of the influx occurring by active transport. Most of the calcium loss occurred across the gills, and the urine contribution was small. Calcium-depleted animals showed only a small fall in haemolymph calcium concentration and calcium uptake was not significantly increased by depletion.