In crustacean, immunoreactive peptides were detected with salmon-calcitonin antibodies by immunocytochemistry in its eyestalks and by radioimmunoassay in the haemolymph and the digestive tract. Two different molecules were purified: the first with their molecular weight comprised between 3-5 kDa, the second having a molecular weight of 22 kDa which could correspond to a precursor of the first one. Their characterization is on progress.