Antimicrobial peptides (AMPs) are small, gene-encoded, cationic peptides that constitute important innate immune effectors from organisms spanning most of the phylogenetic spectrum. AMPs alter the permeability of the pathogen membrane and cause cellular lysis [63] . In bivalves, they were first purified from mussel hemocyte granules [64, 65] . In mussels, the AMP myticin C was found to have a high polymorphic variability as well as chemotactic and immunoregulatory roles [66, 67] . In clams, two AMPs with similarity to mussel myticin and mytilin [68] and a big defensin [69] are known.