ABSTRACT
Holthuisana transversa (von Martens) utilizes the haemolymph as a storage site for ions reabsorbed from the cuticle in premoult. 66 % of the total body calcium, magnesium and phosphate from the preceding intermoult stage was stored in the haemolymph in premoult. Almost all of the calcium and phosphate and 73 % of the magnesium in the haemolymph was located in microspherules of average diameter 0·25μm. The concentration of total calcium in the haemolymph in premoult was 150 times the normal intermoult value (13·2 mmol 1-1) but the activity of calcium in the haemolymph decreased from an intermoult value of 4*52 mmol 1-1 to 3·37 mmol 1-1 in premoult. Postmoult crabs absorbed calcium from the water at a high rate and showed a high affinity for calcium ions; Km = 0·105 ±0·013 mmol 1-1 Ca.
