The Venomous Blue-Ringed Octopus

The blue-ringed octopus - Hapalochlaena lunulata - is said to carry enough venom to kill 26 people. This small animal spends much of its time in hiding, camouflaged. But when disturbed, the octopus flashes around 60 beautifully iridescent blue rings and, when strongly harassed, bites and delivers a neurotoxin in its saliva. Don't pick one up!

The flashes are extremeblueringedoctoly fast: much faster than generally seen with octopus. According to a study published in November's Journal of Experimental Biology, the octopus achieves the fast flashes using muscles under direct neural control. "A fast, conspicuous an advantage to predators, who are warned before attacking a venomous creature, and of course to the octopus itself, as it avoids being eaten." says zoologist Lydia Mathger and lead author of the study.


Blue-ringed octopus live in tide pools and coral reefs in the Pacific and Indian Oceans, from Japan to Australia. There are around 10 different species, all very small. While resting, this blue-ringed octopus is a pale brown to yellow color depending on its surroundings.

Two types of poison secreted by two separate poison glands are used against prey and predators. One of the poisons is used for hunting crab, the other, the extremely toxic one, is used as self defence against predators.

The octopus's parrot-like beak easily penetrates a websuit. Their venomous saliva can have dramatic effects within 15 minutes. For the first few minutes, though, if you are bitten you may feel no discomfort. Any close contact with this octopus should be treated as life-threatening immediately, as there is no antidote.

Further Reading:
How does the blue-ringed octopus (Hapalochlaena lunulata) flash its blue rings? doi: 10.1242/?jeb.076869 November 1, 2012 J Exp Biol 215, 3752-3757.


Venomous Animals of the World, Steve Backshall

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