Environment Getting tentacles around toxins

Getting tentacles around toxins

Australia’s blue-ringed octopus is known for its unique appearance — with striking iridescent blue rings that flare when the creature is in danger — but it also holds deadly secrets.

Naturalists don’t know exactly how it evolved to store large quantities of the potent neurotoxin, tetrodotoxin, within its tissues and venom gland.

Blue-ringed octopi are the only octopods to use large amounts of tetrodotoxin.

So a team from James Cook University, led by PhD student Brooke Whitelaw, set out to solve some mysteries.

Ms Whitelaw said the team sequenced and examined the genome of the southern blue-ringed octopus.

“We found that the southern blue-ring octopus displays a different venom composition to other octopods, which do not possess tetrodotoxin,” she said.

“Most other octopods carry an array of venoms within them. We found differences in the blue-ringed octopus’ genes that suggest the quantity of tetrodotoxin within its venom may be so potent that many toxins necessary to other octopods are not required by the blue-ringed octopus to hunt and protect itself.”

She said the origin of tetrodotoxin in the blue-ringed octopus is still under investigation, however, some bacterial species are known to produce tetrodotoxin in the marine environment.

“Identifying, which species are capable of producing tetrodotoxin and the possible relationship between the octopus and its bacteria will be a complicated job for the future,” Ms Whitelaw said.

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