Blue-ringed Octopus (Hapalochlaena)

Blue-ringed octopuses are venomous creatures dwelling in Pacific and Indian Ocean tide pools and coral reefs. They favor hiding within crevices, showing skilled camouflage patterns.

When disturbed, they reveal their true vibrant yellow color with eye-catching blue rings, serving as a warning display. One of the four species, the Greater Blue-ringed octopus, glows blue due to light reflectors concentrated in the blue rings5, a phenomenon triggered by muscle movement.

They are small, measuring only 5 to 8 inches, but their toxin, tetrodotoxin, can kill humans swiftly. Their bites are almost unnoticeable until respiratory issues and paralysis set in.

Studies revealed that every octopus carries venom. However, only a few species, like this one, pose a substantial danger to humans.