(Hapalochlaena lunulata) Scientific classification
The blue-ringed octopus is the size of a golf ball, but its venom is powerful enough to kill humans. There is no known antidote.
The octopus produces venom that contains tetrodotoxin, 5-hydroxytryptamine, hyaluronidase, tyramine, histamine, tryptamine, octopamine, taurine, acetylcholine, and dopamine. The major neurotoxin component of blue-ringed octopus venom was originally known as maculotoxin, but was later found to be identical to tetrodotoxin, a neurotoxin which is also found in pufferfish and cone snails. Tetrodotoxin blocks sodium channels, causing motor paralysis and sometimes respiratory arrest leading to cardiac arrest due to a lack of oxygen. The toxin is created by bacteria in the salivary glands of the octopus.
But, just to make sure a human doesn’t accidentally bump up against her, this octopus makes sure she’s brightly coloured and easily seen.
Because octopodes are awesome that way.