Blue ringed octopus Hapalochlaena lunulata  (Northern Species) Found almost anywhere around the Australian coastline this small creature is fairly common I myself have never seen one, only in books and documentaries. The Blue ringed octopus is the most lethal of its kind in the world. It contains a very lethal component in its venom called Tetrodotoxin, or ( TTX ) for short this is the same toxin found in puffer fish flesh.When you look at this relatively small creature it definitely has all the bases covered, not only has it got a visual warning system  it also possesses a murderous venom. The bite is virtually painless and sometimes goes unnoticed, although the effects of the venom is almost immediate and sometimes fatal. The beautiful blue iridescent display I mentioned before is by pigment cells called chromatophores, these chromatophores are controlled by nerve endings, This reminds me of bioluminescence in a way it is very similar visually. This stimulation of the chromatophores is a process used to fend off predators. The whole process can be turned on and off much like a light. Box Jellyfish (Chironex fleckeri) Confined to tropical waters the Box Jellyfish has been responsible for many deaths, since early white settlement, the indigenous people of Australia have lived with and known about the dangers of this creature for 60.000 years.  I have felt the sting of the Box Jellyfish whilst spear fishing it was only a minor sting that ran up my right side. I have no doubt it was a Box jelly, because I had seen photo’s of victims years earlier, the red to purplish welt marks and location at the time could only point to one thing, the scars lasted roughly 2 months or so. The stinging cells are within the tentacles and are called Nematocysts, vinegar deactivates these Nematocysts and prevents most of them from further firing off lessening the degree of envenomation. Methylated spirits should never be used as this triggers off more stinging cells upon contact, the “stinger” season is either side of October to May. Just recently I watched a group of people pulling a drag net through the water on one of the northern beaches although they were not specifically targeting Box Jellyfish I was quite surprised at the amount they were pulling in. They ranged in size from about 3cm to 10cm across the bell, but these were only little fella’s. The Box jelly can grow up to 20cm across the bell. Yellow bellied sea snake or pelagic (Pelamis platurus) Sea snakes are fairly common in tropical waters and are encountered by many divers. They are usually quite shy and retiring like their terrestrial relatives and like their land based relatives they have developed some very unusual characteristics to suit their marine habitat. They are air breathers just like land snakes. The interesting adaptations are, valvular nostrils to prevent water from entering their respiratory system, a paddle shaped tail for better propulsion, also their right lung extends all the way down to the tail region, thus increasing their oxygen capacity, they can also absorb oxygen through their skin. There have been no recorded deaths from sea snake bites here in Australia, but there is no doubt they do have the potential to kill. There is one species only to date that comes onto land to lay its eggs, that is the Banded Sea Krait, Very little is known about sea snakes. I have seen a couple of sea snakes, one I found dead washed up on Cable Beach in the N/W of Western Australia I think this could have been the olive sea snake. Admiral’s cone shellfish (Conus ammiralis) The cone shellfish can be found right around the northern coastline of Australia stretching into the more southerly regions. There is quite a number of different species of the cone ranging in different sizes andcolour variations. They are a very attractive looking shell which I suppose would make them dangerous to man due to the fact anyone coming across one of these beautifully marked shells could not resist the urge of picking it up. If anyone is home at the time they risk a sting from the cone shell, a tiny dart is driven into the victim via their snout they can kill, not all species of cone shell process the ability to kill, to date there is only onespecies that is a known killer of man and that is the Geographer cone it can grow up to 13cm in length and weigh as much as 2KG. In the larger species the darts are around 1cm in length and are barbed on the end, the dart is coated in venom before being driven home.