Their salivary glands harbor dense colonies of TTX-producing bacteria. The blue-rings have evolved a symbiotic relationship with the bacteria, providing them ideal living conditions while using the toxin they produce to subdue prey and as part of their highly advertised defense. TTX is particularly effective blocking the propagation of nervous impulses in mammalian myelinated peripheral nerves which produces flaccid voluntary muscle paralysis. This interferes with the muscles of the diaphragm and chest wall and leads to respiratory failure. One milligram of TTX can kill a person, making it one of the most potent natural toxins known.
Treatment consists of life-supportive measures including artificial ventilation.
Patients who survive 24 hours typically make a full recovery, unless lack of oxygen to the brain has caused permanent damage. Interestingly, blue-ringed octopuses are not affected by TTX, probably because they have evolved a slightly different sodium channel receptor that does not interact with the TTX molecule. As an aside, TTX plays interesting roles in various human rituals. It is estimated that each year close to a hundred people die from eating fugu that has not been properly prepared. Please read the FAQ page before asking questions.