Last updated: May 25, 2018 at 16:57 pm
Blue-ringed octopus (genus Hapalochlaena) — This small cephalopod measuring 2 to 20 cm (0.8 to 8 in.) and weighing 10 to 100 g (0.35 to 3.5 oz) injects the neurotoxin tetrodotoxin contained in its saliva when it bites into its prey, which mostly consists of small crabs. The venom, for which there is no antivenom, causes paralysis, respiratory arrest, and possibly cardiac arrest. A single octopus reportedly carries enough venom to kill several adult men. Fortunately, the blue-ringed octopus is not an aggressive animal and it does not seek contact with divers. Nonetheless, it may on rare occasions bite and thus incapacitate—or even kill—a human if it feels threatened or in the case of accidental contact. As a result, less than 20 people are believed to have died from such bites throughout the octopus’ range during the last century. At least 10 species of blue-ringed octopus are found in tidepools and shallow water from Japan to Australia.
Jacups, Susan & Currie, Bart. (2008). Blue-ringed octopuses: a brief review of their toxicology. Northern Territory Naturalist. 20. 50-57.
Williamson, John A. (1996). Venomous and Poisonous Marine Animals: a Medical and Biological Handbook, UNSW Press.
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Jeffrey Gallant is the Editor-in-Chief and Records Keeper of the Diving Almanac. He is also a contributing editor of DIVER Magazine, and the scientific director of the Greenland Shark and Elasmobranch Education and Research Group (GEERG). Jeffrey started diving in 1982.