The small, highly venomous, but usually inoffensive, blue-ringed octopus live in pools on the rock platforms all around the Australian coastline. Any swimming beach with rock rubble could have hundreds of these animals. They are less active during daylight than at night, when they move around search for potential mates. They flash blue and are at their most dangerous only when mating, attempting to warn off predators or angered by being disturbed, frightened or injured. The few reported cases of blue-ringed octopus injuring humans tend to involve an octopus that had been picked out of its pool and provoked or stepped on.
Though these shy animals usually pose little danger to swimmers, a bite from a blue-ringed octopus can kill an adult human and its venom contains the same toxin that puffer fish produce. The only treatment is heart massage and resuscitation. While death can occur within 30 minutes of a bite, a bitten human given urgent resuscitation should recover. Only four human deaths have been attributed to the blue-ringed octopus toxin.
In the 1960s, Sutherland Shire in the Australian state of New South Wales set up warning signs about blue-ringed octopus at its North Cronulla, Cronulla, Shelly and Oak Park beaches, although no-one could recall any octopus bites. Signs at the Malabar Pool and Maroubra’s Mahon Pool in Sydney’s Eastern suburbs also warn about blue-ringed octopus.
While ocean pools with pumps could unwittingly pump in octopus along with the sea water, over a 20-year period only one blue-ringed octopus has been found in Wollongong’s Continental Baths.