Lately, I’ve been obsessed with the really creepy, weird-looking marine creatures of the deep.  The Blue-Ringed Octopus is not that weird to look at.  We’re all familiar with the octopus.  This little guy can even be quite a good-looking creature when startled.  When resting, this octopus ranges from a pale brown to yellow color.  Its blue spots may be faintly visible when resting. [tweetthis twitter_handles=”@sciencealcove”]When startled, the Blue-Ringed Octopus displays pulsating bright blue rings all over its body.[/tweetthis]

Lesser Blue-ringed octopuses, Hapalochlaena maculosa, are the larger and more common of this octopus group. They are found only in the temperate waters of southern Australia, from southern Western Australia to eastern Victoria from 0-50 meters in depth.  Hapalochlaena lunulata or Greater Blue-ringed Octopuses have much larger blue rings when scared.

Blue-Ringed Octopus Hapalochlaena lunulata; Elias Levy, CC BY 2.0, via flickr

Blue-Ringed Octopus
Hapalochlaena lunulata; Elias Levy, CC BY 2.0, via flickr

They can be found in shallow reefs and tide pools from northern Australia to Japan, including Papua New Guinea, Solomon Islands, Philippines, and Indonesia and as far west as Sri Lanka at shallower depths of 0-20 meters.

The Blue-ringed Octopus feeds on small crabs and shrimp.  It feeds during the day and thus is a diurnal creature. It uses toxic venom to kill or immobilize its prey.

Blue-ringed octopuses have an interesting lifecycle in that both males and females sacrifice their lives for love!  The male dies immediately soon after inseminating a female perhaps due to the female attacking him to stop his overtures.  So much for true love 🙁  The female lays 50 to 100 eggs which she guards with her life.  She literally gives up her life taking care of her brood as she is unable to eat while caring for them.  It takes about 1 to 2 months for the eggs to hatch and in that time she starves to death.  Unique to cephalopods, these octopuses emerge from eggs as tiny adults.


Blue-ringed octopus is fearsome but not because it is an aggressive, man-eating monster. Click To Tweet In fact these creatures are quite small, measuring from 5 to 10 cm in length.  As well, they tend to avoid confrontation. I myself prefer the same!  When startled, these creatures will blend into their surroundings by pressing as flat as they can into the ocean bottom.  [tweetthis]What makes these creatures fearsome is the toxins found in their saliva.[/tweetthis] If you step on them or provoke them they will eject a neuromuscular venom containing tetrodotoxin (TTX) which causes paralysis.

Subsequent work demonstrated that the maculotoxin is in fact TTX. TTX is found not only in blue-rings and many fishes in the family Tetraodontidae (hence the name tetrodotoxin), but also in several other groups of animals including California newts (genus Taricha), central American harlequin frogs (genus Atelopus),as well as a scattering of invertebrates including a South American tunicate (sea squirt), a sea star, several snails, some xanthid crabs, a horseshoe crab, two ribbon worms, some arrow worms, and a flatworm. It was a mystery why such a diversity of unrelated organisms would all evolve the same toxin, until it was recently discovered that bacteria associated with many of these animals actually produce TTX. This is the case in blue-ringed octopuses. Their salivary glands harbor dense colonies of TTX-producing bacteria. The blue-rings have evolved a symbiotic relationship with the bacteria, providing them ideal living conditions while using the toxin they produce to subdue prey and as part of their highly advertised defense. — Dr. Roy Caldwell, University of California at Berkeley

These poisons are more toxic than any found in any land animal.

Eating puffer fish may expose you to a similarly toxic tetrodotoxin but puffer fish will not bite you when startled only balloon-up in cartoon fashion.  It is possible to be bitten by these octopuses or exposed to the toxin without feeling much of anything.  Until the onset of symptoms — nausea, vision loss and blindness, loss of senses, loss of motor skills, respiratory arrest — you may not even realize you’ve been attacked!  Recovery from this potentially fatal poison is rare unless attended to quickly with extreme measures, as there is no known antidote.

Because these octopuses do not shoot out black ink when threatened they are a favorite addition to marine aquariums.  Due to the fact some people may not be aware that picking up one of these creatures may be fatal or be unaware of the hazards involved in handling these creatures at all, it is not recommended to keep these beauties as pets.  Admire from afar and leave the photography to the experts!

Greater blue-ringed octopus. Hapalochlaena lunulata. Taken at Tasik Ria, North Sulawesi, Indonesia. Jens Petersen (Own work), CC-BY-SA-3.0, via Wiki Commons

Greater blue-ringed octopus. Hapalochlaena lunulata. Taken at Tasik Ria, North Sulawesi, Indonesia.
Jens Petersen (Own work), CC-BY-SA-3.0, via Wiki Commons




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