Greater blue-ringed octopus (Hapalochlaena lunulata) live in tide pools and coral reefs in the Pacific and Indian Oceans, from Japan to Australia.
They are recognized as one of the world's most venomous marine animals. Despite their small size, 12 to 20 cm (5 to 8 in), and relatively docile nature, they are dangerous to humans if provoked and handled.
They can be identified by their characteristic blue and black rings, and yellowish skin. When the octopus is agitated, the brown patches darken dramatically, iridescent blue rings, or clumps of rings, appear and pulsate within the maculae.
They hunt small crabs, hermit crabs, shrimp, and other small crustaceans.