Convergent and parallel evolution in a voltage-gated sodium channel underlies TTX-resistance in the Greater Blue-ringed Octopus: Hapalochlaena lunulata.

The natural history and pharmacology of tetrodotoxin (TTX) has long intrigued biologists. This toxin has a remarkable distribution that spans two domains of life (Bacteria and Eukarya). Within Eukaryotes, TTX has only been identified in animals but is known to be present in over five-dozen species of phylogenetically distant Metazoans.