BEAUTIFUL BUT DEADLY
Famous for being some of the world's deadliest animals, blueringed octopuses are usually quite docile and spend most of their time hiding in rubble and shells. There are between 4 and 10 species in the Hapalochlaena genus, living in shallow seas from Australia to Japan. They are all less than a handspan in size, and each has around 60 bright blue rings which flash as a warning when the octopus feels threatened. The rings contain multilayer reflectors, arranged to reflect blue-green light. The flashing is controlled by muscles that pinch in a surrounding layer of black pigmented chromatophore cells that cover the blue iridescence. When the muscles relax the blue iridescence is exposed. The warning flashes come before the octopus deploys its deadly defensive bite. Bacteria living in their salivary glands make tetrodotoxin, TTX, the same toxin that makes pufferfish deadly to eat. Female blue-ringed octopuses cover their eggs in TTX to protect them from getting eaten.
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Esta historia es de la edición November 2021 de BBC Focus - Science & Technology.
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