The Blue ringed octopus is one of the most deadly marine creatures, using venom to paralyze prey and camouflage to hide. The Blue ringed octopus is mainly found on the coast of Australia. Although small they stand out because of the bright blue rings it flashes when enraged or scared. There are three different species of the octopus, varying only slightly by size. Each carry venom and blue rings.
Octopus’ consist of three main parts, mantle cavity, foot, and visceral mass. The mantle cavity consists of a very fine tissue that covers a majority of the mollusks body. The visceral mass consist of the body main internal organs. The foot is a strong part of the body that is split into tentacles used for grabbing prey and swimming. Octopus’ have a radial symmetry which means it can be divided into equal halves more than two times. The word Cephalopod means “head-footed” which means that the body is just a head and a foot. An octopus’ body has no bones and no out side shell to protect it causing them to hide and use different methods of protection such as camouflage. Having no bones can be good enabling the octopus to squeeze into tight spaces and hunt for food or hide.(Prentice Hall,706-707) The eyes of this octopus are highly developed. Octopus’ have excellent eyesight in fact their eye is like ours but they have and inverted retina meaning that the lens shape stays the same as the retina moves to gain focus. Octopus’ are very intelligent and have a very well developed brain that takes the shape of a donut. The octopus has three hearts that are placed in the middle and over each gill. Each gill sits in the mantle along with all the other organs. The octopus uses a form of jet propulsion to move around. They accomplished this by forcing water out of a siphon which they can move in different directions to swim head or foot first. 
Internal fertilization occurs in the octopus' breeding habits. The male octopus when mating gets on the females back almost covering all of her body except her tentacles. Then he places a packet of sperm into the females oviduct. Where they form eggs, which she lays and protects. The male octopus when mating gets on the females back almost covering all of her body except her tentacles. Then he places a packet of sperm into the females oviduct. Where they form eggs which she lays and protects. The female octopus lays 50-100 eggs once these eggs hatch the mother octopus dies from starvation. To win his mate over the octopus creates displays of color and body expansion. Chemicals are also released into the water as stimulants and hormones. Flashes of color and chemicals seem to be a way of communicating between mates and others of their own species. All patterns are shown on one side of the acting male as not to make other male octopus' curious as to whats going on.
The blue ringed octopus is mainly found on the Australian coast and on Japan‘s coast, in shallow tide pools that range from 1 to 20 meters deep, hunting for prey. The main diet of a Blue-ringed octopus consists of small crabs, shrimp and other tiny crustaceans .  The octopus bites it’s prey and injects a toxin through it’s saliva . This toxins quickly paralyzes the prey and enables the octopus to consume the animal with is sharp beak.  Though the octopus has bitten people it has only resulted in three known deaths. The octopus usually only bites if it is provoked in some way or another. The people bitten almost always fully recover. 
The venom used by the Blue Ringed Octopus is used for paralysis and defense. Neurotoxins target the nervous system of an organism often causing paralysis and restriction of muscle use. Neurotoxins are usually transmitted by poison glands or saliva. Paralysis aids in consumption, often the octopus' prey is still alive during consumption. Tetrodotoxin, the kind of neurotoxin found in the blue ringed Octopus, blocks sodium channels. This neurotoxin is very lethal and can kill even a human if they do receive proper treatment.
Scientists hope to use these highly lethal neurotoxins to their advantage. The only use so far found in tetrodotoxin is it's ability to be used as an anesthetic. Tetrodotoxin has the ability to work very quickly and last for long periods of time. In one experiment on a rabbit a 10mm injection worked for eight hours. The power of this neurotoxin is hoped to be tapped for many medical uses.
- Octopus Wikipedia
- Phylum Mollusca
- Robert Moore
-  BBC
-  Aims.gov
- Octopus Behavior
- Octopus Poison
-  Dangerous marine animals
- Anatomy provived by: Levine, Miller. Prentice Hall Biology. Pearson Education Inc. , Boston, 2008