Either of two species (Hapalochlaena maculosa, H lunulata) of small octopi which habitat tidal pools in the Pacific Ocean including the Great Barrier Reef. They have up to golf ball sized bodies and measure 8–10 cm when stretched from one tip of the tentacle to the other. They carry enough venom to kill 26 adult humans. When at rest, they are brown-pale yellow; when disturbed, they turn bright yellow and display blue rings around their tentacles. Blue-ringed octopi release tetrodotoxin (formerly known as maculotoxin, produced by bacteria in the host’s salivary glands), an inhibitor of action potential which blocks sodium channels, causing motor paralysis and respiratory arrest. The completeness of the motor paralysis is such that victims cannot signal that they cannot breathe.
Management There is no antidote; rescue breathing must begin immediately and must be maintained for as long as it takes for the toxin to work its way out of the victim’s body—up to 24 hours