Blue-ringed octopus



The blue-ringed octopus is a small invertebrate living the south Pacific and Indian Oceans. There are several species of blue-ringed octopuses, as this group of animals is a genus. There are at least four different species, and there might be as many as ten, but scientists have not yet decided how many there are.

In case you could not find the blue-ringed octopus in the picture above, the one below is a lot easier to spot. It also shows you more what they look like. When not camouflaged like the one above is, these animals are mostly yellow. They can even be a brighter yellow than the one shown below! Most of these octopuses have between 50 and 60 blue rings.

The blue rings are not always as bright as they are below, and they are usually dark blue. When the octopus is disturbed, the rings almost immediately turn to the iridescent blue you see below.



Oh, did I mention that this octopus is venomous? Well, it is. And when I say venomous, I mean REALLY venomous. They are the most venomous octopuses, and one adult has enough venom to kill twenty-six adult humans! It is estimated that the toxin in their venom is 1,000 times as powerful as cyanide!

Another thing that makes the blue-ringed octopus extremely dangerous is that it has a very strong bite. They can even bite through a divers wetsuit! There is also no known antidote for the bite, and their bite is painless. People have handled this octopus and been bitten, but they didn’t know they were bitten until the venom started causing problems!

The venom causes temporary paralysis, making the heart and lungs stop working. Since there no antidote, most people who are bitten die. The only way people can survive is if they quickly receive artificial respiration and continually receive it and a heart massage, which helps the heart keep working.


One thing that makes this creature’s venom even more amazing is the size all that deadliness is packed into. Even as adults, blue-ringed octopuses are only the size of golf balls when curled up! Even when all their tentacles are stretched out, this octopus rarely reaches more than six inches (15 cm) across!

They are also very light. They weigh on average about 1.4 ounces (38 g), or just a little more than the weight of two DVDs! Females are normally slightly larger than the males.

Diet and hunting

Blue-ringed octopuses are day-time hunters. As they are venomous creatures, they can take on prey much larger than themselves by merely envenoming the creature rather than overpowering it. This is a good thing when you remember how small they are!

There are actually two ways this octopus envenoms its prey. It can do the obvious one and bite its prey, injecting venom, or it can choose the less obvious way, expelling venom into the water, and waiting for its prey to accidentally take the venom into its body with some water.

The blue-ringed octopus’s favorite food is crab. They will also eat other crustaceans, such as shrimp, and small fish.

Habitat and range

These mollusks live in the Indian and Pacific oceans, mostly near the coasts of Australia. They typically do not live near northern Australia, but they do live in the east, south, and west parts.

These creatures live in shallow waters rarely deeper than 160 feet (50 m). Because of this, they live fairly close to the shore. This is another thing that makes them more dangerous to humans, as they live in areas where humans are more likely to interact with them.

Reefs are the blue-ringed octopus’s favorite habitats as they provide more places to hide from predators, and they are also inhabited by more animals that could become their meal.

Status and threats

No major conservation site has classified the status of the blue-ringed octopus. They are also not protected anywhere, so they must not be severely threatened.

There are no known natural threats to the blue-ringed octopus. They are sometimes captured for use in aquariums, and some people even have them as pets, despite their deadly bite. This deadly bite is another reason they are threatened by humans. People who are scared of blue-ringed octopuses often kill them out of fear, even though they are not known to bite unless disturbed.

Since these animals live on beaches that are frequented by humans, they are affected by habitat degradation and pollution.

Reproduction and young

Female blue-ringed octopuses initiate the breeding process by the way they position and color themselves. When a male notices an eligible female, he will start courtship, and the pair caresses each other. He then fertilizes the female’s eggs.

Shortly afterward, the female will lay 50 to 100 eggs on the undersides of her arms. They develop here for one to two months, with the female protecting them from predators. During this time she does not eat.

Although the baby octopuses are only 0.16 inches (4 mm) long at birth, the develop quickly, and actively hunt their prey within a month! The blue rings do not appear until they are six weeks old. To give you a perspective of how small the young are, an average adult’s fingernail is more than twice as far across as these babies are long!

After just four months, the young are ready to mate. The females die soon after their eggs hatch, and the males usually die soon after mating as well.

Don’t forget to scroll down and comment your guess about what the next animal is!



Photo credits:

  • Blue-ringed octopus1 – David Breneman
  • Blue-ringed octopus2 – Jens Petersen
  • Mystery animal – Benjamint444
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