Blue-ringed octopus

Blue-ringed octopuses are a group of four small but extremely venomous octopus species. They live in tide pools and on coral reefs in the Pacific and Indian Oceans, from Japan to Australia. They are only 12 to 20 centimetres long, about the size of a golf ball without the arms, and are usually calm.

Their yellowish skin is marked with blue and black rings. When they feel threatened, the 50 to 60 rings flash bright iridescent blue in about a third of a second as a warning. The four confirmed species are the greater, southern, blue-lined and Bay of Bengal blue-ringed octopuses, with more still being studied.

Why are they dangerous?

The venom contains a powerful neurotoxin called tetrodotoxin, which can seriously harm people. The octopus is not aggressive and usually bites only when it is handled or provoked, so the safest rule is never to touch one. They eat small crabs, hermit crabs, shrimp and other small sea animals. They are calm animals that would rather hide than fight. Resting, they look yellowish brown and plain, so the sudden blue flash is a real shock to a predator.

Hiding and short lives

Blue-ringed octopuses spend most of the time hiding in crevices and use skin cells called chromatophores to blend in. Like all octopuses they can squeeze into tiny cracks, and they pile rocks outside their home to help protect it. A typical life lasts only two to three years. They look cute, but they must never be picked up. they must never be picked up.

On the globe

The model shows a small octopus with bright blue rings. Look for it in shallow Australian and Indo-Pacific seas.