Abundance of cDNA transcripts in venom glands of Protobothrops flavoviridis and Ovophis okinavensis , as a percentage of the respective transcriptomes. Abundant transcripts mask the presence of most venom constituents, some of which are six orders of magnitude (106-fold) less abundant. For the sake of legibility, only toxins comprising ≥1% of either transcriptome are shown here. Toxin class abbreviations are as follows: CRISP, cysteine-rich secretory proteins; CTL, C-type lectin-like proteins; CTL F IX/X, C-type lectin-like activators of Coagulation Factors IX/X; LAO, L-amino acid oxidase; MP, metalloproteases; NGF, nerve growth factor; PLA2, phospholipase A2; and SP, serine proteases. These two venoms are starkly different in composition. Protobothrops venom comprises modest titers of eight toxin families, while Ovophis venom consists overwhelmingly of SPs (93.1%) with a lesser quantity of MPs (4.2%). Both venoms contained arrays of lesser constituents, which also varied dramatically between the two species.