Blue Ringed Octopus Size: Ultimate Guide

blue ringed octopus size

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Today we’re going to take a closer look at the blue ringed octopus size and go through just how big it really is as well as why it is one of the most deadly animals on earth.

The blue-ringed octopus is widely known for being more venomous than any terrestrial or land-dwelling animal.

They live in shallow waters ofter sitting on the bottom of the seafloor. They can be found from the Sea of Japan down to the waters of Southern Australia; across from the Philippines to Vanuatu.

The blue-ringed octopus ranges from four to six centimeters long and has eight arms that reach lengths of between seven to ten centimeters long. It’s an incredibly small octopus that can often be overlooked, especially due to its ability to camouflage.

How Big Are Blue-Ringed Octopus?

The size of a blue-ringed octopus will differ depending on the species but grow to a maximum of 15 – 20 centimeters long, with many being only 10 centimeters.

They’re incredibly small octopuses that are highly toxic and lurk in the shallow coastal waters of the Pacific and Indian Oceans.

There are currently four recognized species of blue-ringed octopus; The greater blue-ringed octopus, the southern blue-ringed octopus as well as the blue-lined octopus.

A fourth species is only known from a single specimen, but there may well be more species out there that have yet to be discovered.

These tiny octopuses can sometimes be no bigger than your fingernail, which makes them incredibly difficult to spot in the wild and immensely dangerous.

How Big Is The Biggest Blue-Ringed Octopus?

Blue-ringed octopuses range in size from about 10 – 20 centimeters and spend most of their time hiding in cracks and crevices along coastal waters.

They are more active at night, feeding mostly on small crustaceans such as crabs and shrimp.

The Greater Blue-Ringed Octopus (Hapalochlaena lunulata) is the largest of the four species, however, they still only weigh around 10 – 100g, and are between 10 – 20 centimeters when fully stretched out.

Even the largest blue-ringed octopus is still very small, and can often be overlooked or difficult to find due to its camouflage ability.

Can You Touch A Blue-Ringed Octopus?

Blue-ringed octopuses are easily identified by their yellow skin and blue rings that grow brightly and pulsate when the animal is threatened.

A single octopus can carry enough venom to kill 26 adult humans, making them one of the most venomous marine animals on earth.

If you ever do encounter a blue-ringed octopus in the wild, you should stay out of harm’s way and certainly do not touch or try to pick one up.

If this octopus feels threatened or intimidated, it can bite you with its parrot-like beak that it uses to inject venom into its prey.

One bite from this tiny octopus can leave you fighting for your life in minutes, so it’s best to admire this beautiful creature from afar.

Why Are Blue-Ringed Octopuses So Small?

The venom a blue-ringed octopus carries is 1000 times stronger than cyanide, and yet this tiny octopus is no bigger than a golf ball.

This beautiful octopus is one of 300 species of octopus globally, but it’s also one of the smallest species in the entire world and will usually only grow to around 2.5 inches in length.

Their name comes from the famous blue rings that pulsate and flash on their bodies when they feel threatened or intimidated, but people often mistake them for harmless due to their size.

The blue-ringed octopuses’ size is largely down to evolution. They pack such a strong punch with their venom, that they do not need to be as large as say the Giant Pacific Octopus.

One bite off this octopus is enough to kill predators multiple times over, so there is no need for them to be any larger than they are.

Being small also has its advantages, they require less food to sustain themselves and require less space to survive.

Smaller animals also tend to breed much faster, with helps the species to thrive and maintain itself.

Like all octopuses, the blue-ringed octopus also has a short life span, only 1 – 2 years, and they reproduce once in their lifetime.

More On The Blue-Ringed Octopuses Size

All animals are shaped by their evolution, with size being an adaptation to the challenges they will face in life.

The main objective of any animal is to eat, survive and reproduce. Providing the animal is big enough to tick all three of these boxes then there is no requirement to be any bigger.

Being small also means that animals, including the blue-ringed octopus, can survive when there are limited resources.

They may be small in size, but the blue-ringed octopus is mighty in power and is a highly intelligent cephalopod that should not be messed with.

Final Thoughts

The blue-ringed octopus, despite its small size, is one of the most deadly animals in our oceans.

They carry a deadly neurotoxin known as tetrodotoxin which is powerful enough to kill a human in minutes.

They’re often difficult to spot as they have yellow skin and are able to camouflage well within the reefs and coral, but they are covered in small blue rings that pulsate when threatened.

The blue-ringed octopus size varies depending on the size, but the largest of the species, the greater blue-ringed octopus is only around 10 – 20 centimeters.

These incredibly small and unique critters certainly pack a punch, and should not be handled by humans due to the deadly toxin that they carry.

There is no doubt that the blue-ringed octopus is an incredibly beautiful animal.

But despite their small size, they should always be treated with extreme caution, and remember that their flashing rings are not a threat to be taken lightly.

If you are lucky enough to encounter one of these stunning octopuses in the wild, be sure to keep your distance and admire it from afar, and certainly do not try to pick one up.