Greater Blue-Ringed Octopus Profile
Hapalochlaena lunulata is a tiny Indo-Pacific octopus whose tetrodotoxin venom can kill a human. With no antivenom, it is a professional/public-aquarium-only species, never a pet.
Overview
Hapalochlaena lunulata is a small benthic octopus of the Indo-West Pacific, recognised by roughly 60 electric-blue rings, each 7-8 mm across, set on a darker body. The rings flash as a warning signal, each flash lasting about a third of a second. Despite its tiny size, its bite delivers tetrodotoxin and is potentially fatal to humans.
Taxonomy
- Family: Octopodidae
- Genus: Hapalochlaena
- Scientific name: Hapalochlaena lunulata
- Authority: (Quoy & Gaimard, 1832); originally described as Octopus lunulatus (accepted, WoRMS AphiaID 342333)
Habitat
The species ranges across the Indo-West Pacific, from Sri Lanka to the Philippines and from Australia to Papua New Guinea, the Solomon Islands and Vanuatu. It is a solitary, burrow-dwelling animal of shallow mixed seabeds of rubble, reef and sand.
Tank requirements
- Maximum length: about 10 cm including arms; average weight near 80 g
- Temperature: 24-26 degrees C (75-79 degrees F)
- pH: 8.1-8.4
- Salinity: 1.024-1.026 specific gravity
- KH: 8-11 dKH
- Lifespan: about 2 years
- Public-aquarium / professional handling only
Diet
It is a carnivore that hunts small crabs, shrimp and molluscs, and occasionally small injured fish. It uses its beak to pierce the prey's exoskeleton and inject venom from the posterior salivary glands.
Venom
The venom contains tetrodotoxin (TTX). The bite is painless, with symptoms appearing 15 minutes to 4 hours later: tingling and numbness, sweating, weakness, then muscle paralysis and respiratory failure. There is no antivenom; death may follow respiratory paralysis. The octopus itself is resistant to TTX through mutations in its sodium-channel genes.
Breeding
Females lay around 60-100 eggs and guard them, refusing food and dying once they hatch after roughly 50 days; males die after mating. Hatchlings are about the size of a pea and reach maturity the following autumn.