Ask Dr Dazza | Blue Ringed Octopus

Published 2:35pm 25 August 2021

Ask Dr Dazza | Blue Ringed Octopus
Words by Dr Dazza

Every so often people collecting bait or kids around rock pools encounter the blue ringed octopus.

There are four species of blue ringed octopus in the world, with the most common species in Moreton Bay only growing to about 5cm in body length.

They are well known to be along the shoreline of the Redcliffe peninsula. They might be small and shy, but they pack a punch. They frequently feature on internet lists of the top 10 deadly animals from Australia. The good news is that they are not going to chase after you and bite you. Most envenomations have come from people handling the animal and for most people there is never a need to touch them.

When undisturbed, the octopus lacks blue rings. It is only when the animal is threatened that the blue rings appear. The blue rings signal to potential predators to stay away. Blue is a rare colour among animals but when it occurs it often has meaning.

After advertising that you should leave it alone, continuing to bother the animal may see it bite. Most victims do not feel the actual bite because it is so small. However, the onset of symptoms can occur in just minutes. Once this toxin is in your body it shuts down all the nerves in your nervous system. Symptoms of a bite include loss of feeling in the tongue and lips, paralysis, respiratory failure and very occasionally death. The paralysis that overcomes the victim is only to their voluntary muscles; they remain fully conscious. If mouth to mouth resuscitation is given to a victim of a blue-ringed octopus, they should fully recover. There is no anti-venom.

The toxin that does the damage is tetrodotoxin. It is the same toxin that is found in toadfish. The octopus does not make the toxin. It is made by bacteria in the animal’s salivary glands. The toxin is injected into a victim when the animal bites and the amount of toxin that a single tiny octopus contains is enough to kill several adults.

Blue ringed octopus have a life span of only a couple of years. A single female blue ringed octopus only lays between 50 and 100 eggs. The octopus dies after reproducing.

If you are around the Moreton Bay foreshore and see a tiny octopus about the size of a golf ball, admire it but don’t touch it.


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