Blue-Ringed Octopus


  • Blue-ringed octopus are famed for being one of the most venomous animals on the planet.

About Blue-Ringed Octopus

  • It’s a common myth that blue-ringed octopus are found only in the tropics.
  • These tiny marine animals are, in fact, found all around Australia, including Tasmania.
  • The venom of blue-ringed octopus contains tetrodotoxin, a potent neurotoxin claimed to be a thousand times more potent to humans than cyanide. The venom of blue-ringed octopus contains tetrodotoxin, a potent neurotoxin claimed to be a thousand times more potent to humans than cyanide.

    blue-ringed octopus
    Photo Credit: Special Arrangement (The Hindu)
  • First discovered in pufferfish, tetrodotoxin is actually found in more than 100 species including the Panamanian golden frog and rough-skinned newt.
  • But levels of the toxin varies hugely between species, and levels in blue-ringed octopus are high.
  • Tetrodotoxin is produced by bacteria that live inside the host species, the other is that it’s sourced from the diet.
  • Most of these animals use tetrodotoxin for defence, but blue-ringed octopus also use it to hunt and kill their prey, such as fish and crabs.
  • Octopus are short-lived – the blue-ringed octopus only lives for a few months – and are highly responsive to changing environmental conditions.
  • Hypothetically, some human-made habitats, such as breakwalls and lobster pots, or marine litter, such as bottles and cans, could be providing additional habitat for blue-ringed octopus.
  • Octopus populations may also undergo natural “boom and bust” cycles in response to fluctuations in temperature, food, and other factors in their environment, resulting in rapid increases and decreases in population numbers.
  • Deliver venom by biting using their parrot-like beak, which is found at the base of the arms.
  • Bites are rare – they are docile, shy animals and are not interested in people. But they may bite when they are threatened or provoked, so never, ever pick them up.
  • Found in shallow coastal waters, including the foreshore, so accidental encounters do happen.
  • Their preferred habitats include rocky reefs and coral reefs, seagrass and algal beds, and rubble. Given they’re found throughout the Indo-West Pacific.

Symptoms to watch for

  • A mild case of envenomation may result in tingling around the mouth and mild weakness. A severe case may lead to flaccid paralysis (weak or limp muscles), including respiratory paralysis and the inability to breathe.
  • A tricky thing with blue-ringed octopus is that bites may be painless, so people can be unaware they have been bitten. But the onset of symptoms can be rapid (within minutes) and so an equally rapid first-aid response is crucial.
  • You do not need to put anything on the bite, such as vinegar or hot water. Rather, pressure bandaging and immobilisation is recommended, as for snake bites.
  • If the envenomation is severe, first aid is also focused on providing basic life support, particularly breathing support.


  • While there is no antivenom available for a blue-ringed octopus bite, the venom has short-lived effects (usually hours).

Source: TH

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