Basic information about the greater blue-ringed octopus
- Scientific name: Hapalochlaena lunulata
- Common name (English): Greater blue-ringed octopus
- Common name (Malay): Kurita bergelang biru, sotong berbintik biru, kurita cincin biru
Mesmerising, tiny yet deadly – the blue-ringed octopus is a golf ball–sized wonder of the reef. Spotting one takes either serious luck, sharp eyes, or a love for muck diving.
Let’s be clear: this little cephalopod isn’t out to get you. It’s shy and usually non-aggressive. But when it feels threatened, it lights up with glowing neon-blue rings – a clear “do not disturb” signal. In fact, normally it looks quite boring. It is actually usually a milky or beige colour, camouflaging perfectly with sand and rubble.
Don’t let its size fool you. Take the warning of its bright blue rings seriously. This tiny creature carries tetrodotoxin, one of the most powerful neurotoxins on Earth. It is potent enough to paralyse a human, and there is no known anti-venom.
In short: admire, respect, and absolutely no selfies.
Conservation status of the greater blue-ringed octopus
IUCN Red List Status: Least Concern
The blue-ringed octopus has a wide geographical distribution. Harvesting for the aquarium trade does occur, but the extent is not well known. (However, let's leave it alone so it doesn't become endangered. Besides, it is dangerous to try and harvest.)
Blue-ringed octopus habitat
The blue-ringed octopus prefers to live in shallow seabed, such as sandy or rubble zones, reef slopes, or muck sites.
Blue-ringed octopus diet
These octopuses generally eats crabs, shrimp, and small fish. It hunts by sneaking up on their prey, and biting them, delivering paralysing venom. It can then leisurely eat while the prey is immobilised.
How big is the greater blue-ringed octopus?
Despite its name, the greater blue-ringed octopus is a tiny little thing. It is generally no longer than 10cm, including its arms.
In fact, confusingly, it's smaller than the lesser blue-ringed octopus, which is twice as long. The reason for this is that the 'greater' in its name does not refer to its own size, but the size of its blue rings. Its rings are larger than those of its cousin.
How many species of blue-ringed octopus are there?
There are four species under the genus Hapalochlaena. All four are extremely venomous, and show the same bright blue colouring when threatened.
The most striking blue rings belong to the greater blue-ringed octopus because they are bigger. The largest species is the lesser or southern blue-ringed octopus (H. maculosa).
Where can you find blue-ringed octopuses in Malaysia?
These octopuses are found across the Pacific as well as the Indian Oceans.
In Malaysia, divers are most likely to encounter Hapalochlaena lunulata, the greater blue-ringed octopus. Sightings are rare; you’d be considered lucky to spot these critters even at hotspots. Nonetheless, they have been reported in Sabah, and (less commonly) some Peninsular locations.
In Sabah, these locations are in, or near, the Marine Parks of Sipadan and Tun Sakaran:
- Mabul & Kapalai Islands are renowned muck diving hotspots. These locations are especially productive during night dives.
- Sipadan surrounding areas: Look in sandy slopes and coral rubble zones, which are potential habitats.
- Semporna region: Search in the shallow seagrass beds and coastal rubble, and often also near human-made structures like jetties.
In Peninsular Malaysia, sightings are more rare. However, they have been reported in Pulau Tioman and Pulau Redang marine parks, specifically on sandy flats near reef drop-offs, or artificial structures.
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Interesting facts about the blue-ringed octopus
How should you look for the blue-ringed octopus?
When searching for the blue-ringed octopus in coral reef environments, your best chances come from paying close attention to the nooks and crannies of the reef's rubble zones, especially in muckier, sandy, or lagoon-like reef flats. Muck diving sites like those in Kapalai and Mabul are your best bets. Look carefully in discarded shells, cans, or bottles.
Best time to spot: In Malaysia, look for them during the drier months (off monsoon), when there is good visibility and calmer seas.
Night dives increase your chances significantly, because they're more active at night, hunting for small crabs and shrimp. Carry a torchlight and go slow. These octopuses are tiny and rely on camouflage until they flash their rings as a warning.
Spending a lot of time underwater? Consider signing up for conservation diving projects!
What should you do if you see a blue-ringed octopus?
You are not very likely to come across a blue-ringed octopus. However, if you do see one, remember that these creatures are very venomous. One octopus carries enough neurotoxin to kill 26 humans in minutes. Despite this, there has not been a death recorded in Malaysia from one. So let's keep it that way.
- Don’t touch! Their toxin can cause respiratory failure and paralysis.
- Admire from afar: If you’re lucky enough to spot one – congrats! But be sure to maintain a distance!
