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Blue-ringed Octopus

The blue-ringed octopus is a venomous octopus found in the Pacific and Indian Ocean, in coral reefs and tide pool. They are named for the bright blue rings they show when threatened. These warns predators of their toxic bite containing tetrodotoxin, a dangerous neurotoxin. Despite their venemosity, blue-ringed octopuses are mostly docile unless handled. There are four species of blue-ringed octopus.

Normally, blue-ringed octopuses are an unassuming tan color, to help camouflage. It’s only when they feel threatened that their name-giving blue rings appear. A blue line also appears, right through the octopus’ eyes. These octopuses can be between 12 and 20 centimeters (5-8 in). The large variety is because of differences in nutrition, temperature and light. Females are a bit larger than males. Octopus are very quick and flexible because they are invertebrate.

Blue ringed octopuses eat small crabs, shrimp, and fish, hunting at night. They hunt by pouncing on they’re prey, bringing it to their mouth with their tentacles, and injecting them with their venom. The venom paralyzes prey, and also partially digests it. Helpfully, the octopus is unaffected by its own venom.


Image courtesy of Octopus Worlds

In a human, a bite is small and possibly painless, and so might go unnoticed - at least until the respiratory distress, paralysis, nausea, blindness, and heart failure set in after a few minutes! Many of these things are quite serious, but the thing that is most likely cause death is paralyzation of the diaphragm, leaving the victim unable to breathe. Since there is no antivenom, treatment for the bite would include applying pressure to slow the venom, and, once the victim stops breathing, artificial respiration. If artificial respiration is started immediately and continued until the tetrodotoxin is metabolized, most victims survive. One blue-ringed octopus carries enough venom to kill 26 people. Blue-ringed octopuses’ beaks are strong enough to pierce through a wetsuit.

A female octopus lays about 50 eggs in the fall and are incubated under her tentacles for six months. Interestingly, while incubating eggs, a female octopus will not eat! Once they hatch, the eggs will fall to the seafloor and the female will die, after living 1-2 years.

Blue-ringed octopuses have not been evaluated for their conservation status. They’re not usually eaten (maybe because of their deadly poison), but some are captured as pets and they’re generally and unofficially considered threatened because of loss of habitat.

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Works Cited

Helmenstine, Anne Marie. “Meet the Deadly Blue-Ringed Octopus.” ThoughtCo,

“Blue Ringed Octopus.” Octopus Worlds, The Portal of Life on Earth, Biodiversity, Animal Facts,

“Blue-Ringed Octopus Facts, Habitat, Life Cycle, Venom, Pictures.” Animal Spot, 16 July 2020,

Cover Image courtesy of Octopus Worlds

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