Antimicrobial peptides (AMPs) are small peptides commonly ranging from 10 to 50 amino acids and displaying activity against bacteria. Molluscan species only rely on innate immune processes, including secretion of AMPs, to protect against external aggressions. Most of molluscan AMPs have been identified in haemolymph and/or in the circulating cells, the haemocytes in some bivalves. In this respect, immune response of cuttlefish haemocytes has been studied and transcriptomic analysis of several tissues of Sepia officinalis have been conducted.