The Blue Ring Octopus kills humans or predators that disturb it by biting them. There is venom secreted along with their saliva that gets into the bite wound and quickly spreads around the body. This venom blocks signals from being passed through the body's nerves which results in full body paralysis (including the lungs). There is no antidote known yet but a victim can survive if they are connected to respirator or are given mouth to mouth resuscitation until the venom is worn down in the body (usually after about 24hrs). So if you are going to the western pacific make sure you know first aid!

The blue-ring octopus has a kind of venom (poison) in its mouth. When the octopus bites, it injects venom that paralyzes a person's muscles.This includes the muscles that let us breathe. Soon there's no oxygen in the victim's blood and the heart shuts down. After about 4 to 6 minutes without oxygen, the brain starts to shut down. If only a little poison gets in, the person may recover.

One interesting thing is that the octopus itself doesn't make the toxin.There are bacteria that live in the salivary (spit) glands of the octopus that actually make the poison. This relationship between octopi and bacteria is called a mutualism. That means that both things benefit. The octopus gets a poison to kill its predators and prey. The bacteria get food and a safe place to live.

Can you think of other examples of mutualism where plants or animals both benefit from each other?

It has a venomous bite. The venom (tetrodotoxin) is the same as in puffer fish and several other deadly animals. The venom is actually produced by bacteria living inside the octopus. The venom kills by interfering with muscle contraction, including the muscles needed for breathing. If the bite is noticed and rescue breathing ("mouth to mouth") is started immediately, the victim will probably survive. If you have access to the internet, a good reference is available on Wikipedia:

Obviously, no one wants to do mouth to mouth on a villain in a James Bond movie. :-)

The octopus injects venom that paralyzes the breathing muscles of the victim, who then asphyxiates due to the lack of oxygen.