The occurrence of natural agglutinins has been detected in the serum of Emerita asiatica using a panel of mammalian erythrocytes. Variations in agglutinating activity were observed with regard to the different moulting stages of the mole crab. The serum agglutinins showed differential affinities in their carbohydrate binding specificities proving the occurrence of multiple agglutinins in the mole crab. The hemagglutinating activity of the serum from intermoult crabs was high and stable between pH 6 and 8 and that of postmoult crabs between pH 7 and 8 and at temperatures between 20 and 50 ̊C. The serum from crabs belonging to both the stages was found to be dependent on divalent cations for their HA activity in a dose dependent manner. The levels of total and free calcium in the serum showed significant differences at different stages of the moult cycle ranging from 0.9 to 1.9mg/ml of serum. The existence of moult specific agglutinins in the serum of the mole crab E.asiatica is a novel adaptive immune feature among crustaceans to cope up with the susceptibility to entry of pathogens or physiological stress during moulting.