Fertilizing ability of the sperm in marine shrimp depends largely on two major processes – interaction with egg surface and acrosome reaction, since the sperm in these animals are immotile. Sperm of P. monodon undergo unique features of acrosome reaction (AR) that are drastically different from a well-studied penaeoid shrimp, Sicyonia ingentis. AR is completed within 45-60 sec and comprises only acrosomal exocytosis and depolymerization of sperm anterior spike. A natural AR inducer has long been known to be substances released from eggs, so called egg water (EW), which is made up mainly of cortical rods (CRs) and thelycal fluid (TF). CRs were heavily glycosylated, having mannose as a major sugar composite. Biogenesis of the CR proteins began at stage II developing oocyte in the dilated ER complex and then exocytosed as small vesicles into extracellular crypts of the mature oocyte to form a bottle brush structure, a typical feature of glycosaminoglycan in the jelly substances. Physiologically, water-soluble CR (wsCR) had its superior AR inducing ability (comparable to the ability of EW) which was shown to be modulated by the exposed mannose moiety of wsCR. Sperm of P. monodon also possessed trypsin-like enzymes both on the sperm surface and in the acrosomal region. This trypsin-like enzyme is involved in self-regulation of the induction of acrosome reaction which is uniquely distinct from other marine shrimp (where the trypsin activity is derived from EW). Activation of trypsinlike enzyme prior to sperm-egg interaction was also detected in Thai abalone, Haliotis asinina – only sperm that were spawned into seawater engaged high trypsin-like activity but not testicular sperm. Therefore, our results suggest that activation of trypsin-like activity in the sperm of marine invertebrates seems to be an important characteristic that can be used to predict sperm fertilizing capacity (protein biomarker) in marine economic animals at least in the case of our Thai shrimp and abalone.