An understanding of the structure and mode of action of venom found in all octopuses, cuttlefish and some squid can help design drugs for conditions like pain management, allergies and cancer.

"Venoms are toxic proteins with specialised functions such as paralysing the nervous system," Bryan Fry, biochemist from the University of Melbourne, said.

While many creatures have been examined as a basis for drug development, cephalopods (octopuses, cuttlefish and squid) which are venomous - going back to a common, ancient ancestor - remain an untapped resource and their venom may represent a unique class of compounds.

Fry, who led the study, said that while the blue-ringed octopus species remain the only group that are dangerous to humans, other species have been quietly using their venom for predatory activities.

Fry obtained tissue samples from cephalopods ranging from Hong Kong, the Coral Sea, the Great Barrier Reef and Antarctica.

The team then analysed the genes for venom production from the different species and found that a venomous ancestor produced one set of venom proteins, but over time, additional proteins were added to the species’ chemical arsenal.

The origin of these genes also sheds light on the fundamentals of evolution, presenting a prime example of convergent evolution where species independently develop similar traits, said a Melbourne release.

The team will now work on understanding why very different types of venomous animals seem to consistently settle on the similar venom protein composition, and which physical or chemical properties make them predisposed to be useful as toxin.