with further sampling efforts, several other toxin types will
also show to have an earlier evolutionary origin than
recognised based on current data. Our results also revealed
that coleoid venoms are much more diverse than previously
anticipated, rivalling in complexity with more intensively
studied venoms such as those of snakes. It was also
strongly suggested that at least some of these toxins are
actively evolving under selection, with the cysteine-rich
pacifastin and kallikrein types being particularly abundant
and diverse. This is consistent with other venoms, where
the components with the greatest cysteine content are the
scaffolds most amenable to structural and functional
mutations (Casewell et al. 2011; Chang and Duda 2012;
Fry et al. 2003; Kordis and Gubensek 2000; Weinberger
et al. 2010; Wong and Belov 2012). In contrast, the globular
enzymes such as carboxypeptidase and hyaluronidase
showed extremely little variation, consistent with globular
enzymes from other venoms (Fry 2005) that have a threedimensional
structure driven by non-covalent interactions
and a single amino acid change could decimate the correct
folding.