from where it is transferred through the hemolymph and via the epidermal layer underlying the cuticle to the exoskeleton (Adachi et al., 2005). We offer a similar scenario for gastrolith hemocyanins, providing some support with the presence of the protein in the connective tissue surrounding the gastrolith pouch, as well as in the cytoplasm of the gastrolith-forming cells, as revealed by immunolocalization. Specific expression in the hepatopancreas, however, does not fully coincide with the tissues from which we obtained our hemocyanin transcripts, namely the gastrolith-forming and sub-cuticlar epithelia. As the gastrolithforming epithelium is highly penetrated by hemocytes (‘blood
cells’) (Ueno, 1980), hemocyanin expression was sought but not detected in these cells. The most probable explanation for this apparent contradiction is the sequencing of residual transcript expression. Sequencing of transcripts that are expressed in very small copy numbers, and are actually non-functional, may be the result of the new next-generation sequencing methods, such as 454-sequencing, given their vast sequencing depth. Transcript expression experiments using the RNA-seq analytical procedure may prove the presented assumption by quantifying the expression.