NCBI Swissprot, NCBI Metazoan Refseq, the NCBI nonredundant and the UniprotKB/Trembl protein databases were chosen to annotate the contigs that were at least 100 bp long (49, 847) . The percentage of contigs annotated with a cut off evalue of 10e-3 was 44.7%. Contig sequences and annotations are included in Table S1 . Of these contigs, 3.26% matched sequences from bivalve species and the remaining matched to non-Bivalvia mollusc classes (4.13%), other animals (81.38%), plants (2.58%), fungi (1.78%), protozoa (1.50%), bacteria (4.95%), archaea (0.20%), viruses (0.21%) and undefined sequences (0.01%). As shown in Figure 3A , the species with the most sequence matches was Homo sapiens with 3,106 occurrences. The first mollusc in the top 35 list was Lymnaea stagnalis at position 11. The first bivalve, Meretrix lusoria, appeared at position 17. R. philippinarum was at position 25 with 124 occurrences. Notably, a high percentage of the sequences had homology with chordates, arthropods and gastropods ( Figure 3B and C), and only 343 contigs matched with sequences from the Veneroida order ( Figure 3D ). These values can be explained by the higher representation of those groups in the databases as compared to bivalves and the quality of the annotation in the databases, which has been reported in another bivalve transcriptomic study [22] . The data shown highlight, once again, the necessity of enriching the databases with bivalve sequences.