And not just any octopus. These are exceptional and their colouration makes them even more spectacular. It is the blue ringed octopus and this video gives a good - if slightly over top - idea of how it looks and behaves.
It's fair to say that Australia is very light on as far as large land predators are concerned. Since the extinction of the thylacine in the 1930s - although there are still occasional reports of possible sightings none have been actually proven to exist since the death of what was apparently a female in Hobart Zoo - the only large apex predator in Australia is the dingo, our wild dog. There are marine predators, of course, but most of them are visitors like the great white sharks and orcas.
On the other hand, like anywhere else in the world, we do have other nasties that can cause much distress or even death. Many of these are very small - and this little critter is one of them.
In the octopus world the blue ringed octopus is tiny. Their bodies range from 5-7 centimetres - about the size of a golf ball - and their tentacles are approximately the same length, depending on species. You can see just how small one is here where it's shown in comparison to a finger tip.
They occur all along Australia's southern and Pacific coast and through the tropics as far north as Japan, living on shallow reefs and in tidal rock pools. Beautifully camouflaged at rest with dark brown to black rings shapes on a beige/ grey background they blend in among the rocks, hiding in crevices and mostly coming out in the evening to feed. To catch small crustaceans and the occasional fish they employ a neurotoxin - tetrodotoxin, the same as that found in puffer fish and some poison dart frogs. This is 1200 times more powerful than cyanide and could easily kill and adult, let alone a child. It induces motor paralysis, leaving the victim conscious but unable to move or speak, and leads to respiratory failure. Death results from lack of oxygen to the brain.
Fortunately for humans, the blue ringed octopus is docile and unless it is provoked or trodden on it's not interested in attacking you. And this is just as well for me because, when I was a child, my family used to go to the south coast for our summer holidays. My brother and I would spend many happy hours roaming the rocky coastline armed with buckets which we filled with seaweed, water and any small creatures we could find in the tidal pools. Our parents ensured we returned them within a few hours but in the meantime we spent a few happy hours studying our catch.
Of it, our absolute favourites were the tiny octopuses that we found almost in every pool. Their ring markings would turn dark blue and pulse while the rest of their body changed colour according to what was around them. Pursued, they would speed across the pools, tentacles streaming behind them. We found them fascinating and tried to scoop them out with a tin can or beach spade. They were very quick so we weren't often successful and we were discouraged by our parents from touching because we might hurt them - fortunately because no-one had any idea then that they could be a danger.
I can vouch for the fact that they are docile, though, because I can't remember one of them going a stage further than their rings turning a rich blue and, despite the stress we undoubtedly put them under, they never showed the bright yellow body and iridescent blue rings that shows up in the myriad of photos on the internet. They were far more intent on hiding.
So, do we need to worry much about the blue ringed octopus? I don't think so. You are more likely to die out for a drive on the road. There have only ever been three reported deaths and, according to what I've discovered while reading up about them, urgent medical intervention with mouth to mouth resuscitation until a ventilator can be used is usually an effective treatment. This doesn't mean they're not dangerous but as long as you avoid handling them - and not going into tidal pools barefoot would probably be sensible - you should be safe enough.