Blue ringed octopus

Scientific name : Hapalochlaena lunulata

Small octopus, with short tentacles and pointed body. Often the tentacles are lifted in a curly way while the animal moves using jet propulsion from the funnel. Typical colour pattern, with large blue rings that can be hidden but usually are shown clearly when a diver is close, as warning colour. Body 5 cm, tentacles 7 cm.
Encountered in lagoon, bay, back reef. Predator of small crustaceans and fish. Its bite is venomous, potentially lethal for man. Rare and difficult to see.
Different Hapalochlaena species exist, all with blue spots and all venomous (probably). The famous species capable to kill humans (3 fatalities from 1950 to today, in Australia and Singapore), often identified as H. lunulata, is actually a different, still undescribed species (Hapalochlaena sp.). H. lunulata is considered dangerous, even if actually no fatalities are known.
In our area confusion is possible with another Hapalochlaena sp., identified by the smaller rings.
Hapalochlaena species host in their salivar glands symbiotic bacteria, responsible for the production of the deadly tetrodotoxin (the same toxin produced by puffer fishes). This venom kills through the progressive (reversible) paralysis of all the volunteer muscles. The death is by repiratory paralysis, and can be avoided by artificial breathing.
It is worth saying that this species is absolutely not aggressive, and the venomous byte is used only as last option.

	Description	Author	Place	Size
	Blue ringed octopus moving	MATTEO GUARDINI	Indonesia, Likupang	796 kB