Blue-ringed Octopus - Hapalochlaena

Photograph by Roger Steene

When disturbed the brilliant display of this cephalopod mollusc instantly identifies it as the blue-ringed octopus. Hapalochlaena is a small 20 cm octopus , dark brown to dark yellow in color, but with brilliant blue rings that "glow" when it is angry. It is found from northern Australia to southern Japan.

This animal possesses a deadly venom capable of killing humans. It is commonly found in tidal rock pools where it feeds on crabs and other molluscs, which it paralyses by injecting poison with it's beak-like jaws which it makes in its salivary glands. Although the painless bite can kill an adult, injuries have only occurred when an octopus has been picked out of its pool and provoked or stepped on. The poison is neuromuscular and produces a muscular weakness and eventually respiratory paralysis. Children should be warned t leave them alone, irresistible as they may seem due to the glowing blue circles.

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