Facts About the Blue-Ringed Octopus

The blue-ringed octopus carries enough poison in its glands to kill 26 people in a matter of minutes. It lives in the Pacific Ocean, from Japan to Australia. The blue-ringed octopus prefers shallow warm water, tidal pools and rock crevices around coastal reefs. This nocturnal hunter is hatched from a "pea-sized" egg and seldom grows larger than a golf ball. When it matures, this octopus is 5 to 8 inches from tentacle tip to tentacle tip.

  1. Appearance

    • The dorsal body of the blue-ringed octopus is covered with wrinkles, making it look like it is covered with "rough" skin. It also has small, rounded projections of various sizes (called tubercles) covering its head and mantle. The blue-ringed octopus does not have an internal or external skeleton, and is therefore very flexible. It can squeeze itself into very small areas, including tiny crevices in the rocks, bottles, cans or other marine shells. It has also been known to bury itself into the sandy bottom to hide. It is normally found as a plain-looking, yellowish-brown octopus, but 50 to 60 pulsing bright blue rings will appear and cover its dorsal and lateral surfaces when it is agitated, which warns predators of its location.

    Toxicity

    • The saliva of the blue-ringed octopus contains two poisons secreted by two separate poison glands. The first poison is used against crabs and other food sources; it paralyzes the muscles of its prey. Inside its mouth, live colonies of bacteria produce a toxin called Tetrodotoxin, which is the same strong toxin found in puffer fish and other animals. The second poison gland stores this Tetrodotoxin, which is deadly to humans. It is used as self-defense against predators.

    Diet and Feeding

    • The main diet of the blue-ringed octopus is crabs, mollusks and shrimp. The octopus catches its prey in its tentacles and bites a hole in the shell of its prey with its beak-shaped mouth. When the octopus bites through the shell of its prey, poison enters the prey's body through the saliva of the octopus. After injecting the toxin into the shell, the blue-ringed octopus uses its mouth and tentacles to tear off pieces of its prey and sucks out the rest of the meat from the shell.

    Reproduction

    • Breeding between the male and the female blue-ringed octopus begins in late autumn. The male blue-ringed octopus has a hectocotylus, which appears like a modified "arm." Inserted under the mantle of the female, the hectocotylus releases spermatophores into the female's oviduct. 50 to 100 eggs may result, and the female octopus carries these eggs under her tentacles to protect them from harm until they hatch in two to three months. Young octopi grow extremely rapidly and are ready to breed by the following autumn. After mating occurs, the males die. The females protect the eggs until they hatch and then die as well.

    Human Contact

    • Divers can limit their exposure to the bite of the blue-ringed octopus by diving during the daytime and being careful when picking up debris from the bottom. The bite of the blue-ringed octopus can cause death in a matter of minutes, and there is no known antidote for the toxin. Some humans have survived the bite by receiving immediate supportive treatment such as heart massage and mechanical ventilation that is continued until the poison has dissipated. Although highly dangerous, some marine aquarium owners have begun adding these small creatures to their home tanks, since it is highly colorful when agitated and does not have an ink sac that would cloud the aquarium. Great care must be taken when housing this deadly creature in a home setting.