Blue-Ringed Octopus

The Blue-Ringed Octopus can be best described as ‘one cute animal that might kill you’. The term blue-ringed octopus does not merely refer to a single species, but a genus of species that are marked by bright blue circular patterns. Despite their apparent gentle nature, these small molluscs are known to be one of the most venomous and dangerous sea creatures on the planet. An adult blue-ringed octopus is of the size of a golf ball, but if provoked, they can bite attackers, including humans. A single bite might lead to partial or complete paralysis, blindness, loss of senses, nausea, and resultant death within minutes, if left untreated. No blue-ringed octopus anti-venom has yet been discovered.

Scientific Classification


Blue-Ringed Octopus

Physical Description

Size: The maximum size of these animals can be 4-6 cm lengthwise (from the top of the mantle to the tip of the arm).

Weight: 10-100 grams, depending on sub-species and age.

Shape: Bilaterally symmetrical.

Rings and Patches: They are typically covered with 50-60 blue rings along the dorsal and the lateral surfaces of the mantle.

Eyes: These molluscs have two well-developed eyes similar to those of the vertebrates.

Tentacles: Like other octopuses, they have four pairs (8) of tentacles attached around their mouths. The lengths of the arms vary between 7 and 10 cm and are covered with suckers.

Beak: They have two strong parrot-like beaks.

Skin (Mantle) Color: Yellowish to bright yellow skin with bluish to bright blue rings or lines (depending on the sub-species). Color changes from light to brighter shades when threatened.


The approximate lifespan of the blue-ringed octopus is two years.

Blue-Ringed Octopus Pictures

Blue-Ringed Octopus Pictures

Blue-Ringed Octopus Eyes


They are distributed across the Pacific and the Indian Oceans, from Japan to Australia. Some subspecies are also found in and around Papua New Guinea, Solomon Islands, Philippines, and Indonesia and as far west as Sri Lanka. Mainly recognized as an Australian species, they are widely spread around the southern part of New South Wales and South Australia, and northern Western Australia.

Habitat: Where do Blue-ringed Octopuses live

The BRO mainly dwells in the temperate waters of the coral reefs and in the tide pools, at a depth varying from 0-20 meters (or sometimes 50 meters).

Blue-Ringed Octopus Habitat

Blue-Ringed Octopus Habitat

Blue Ringed Octopus Photos

Classification of Species

Three distinct species of the ‘Hapalochlaena’ has yet been confirmed, with a fourth type still being researched. Here are the different species, along with their scientific names and descriptions:

  1. Greater Blue-ringed Octopus (Hapalochlaena lunulata): Found in the tropical waters of the Pacific Ocean that can weigh between 10 and 100 grams.
  2. Southern Blue-ringed Octopus or ‘lesser blue-ringed octopus’ (Hapalochlaena maculosa): Found along the southern coast of Australia, they grow up to 20 cm and on an average can weigh around 26 grams. Though paler than the other species, their blue rings turn brighter when they feel threatened.
  3. Blue-lined Octopus (Hapalochlaena fasciata): This species is found between southern Queensland and southern New South Wales in the intertidal rocky shores and coastal waters at a depth of 15 meters (49 feet).
  4. Hapalochlaena nierstraszi : This species was first described back in 1938 from a single specimen from the Bay of Bengal. However, the validity of this taxon has been debated.

Blue-Lined Octopus

Southern Blue-Ringed Octopus

Greater Blue-Ringed Octopus

Behavior and Lifestyle

These marine creatures are not aggressive animals. They hide in crevices or under rocks during daytime for gaining protection, and emerge at night. The main motto of changing its body color is to exhibit its toxicity and warn predators and attackers.

These octopi use their dermal chromatophore cells to camouflage themselves. Like most other octopi, it flattens out its body on the bed for hiding from its enemies. Furthermore, it changes its body color in order to blend into its surroundings.

They are bottom dwellers, inhabiting sandy and silty areas, and would even live inside empty sea shells, discarded bottles, and cans. The BRO will come out of its shelter only to hunt for food or to search for a mate.

Blue Ring Octopus

Blue Ring Octopus

Blue-Ringed Octopus Images

Blue-Ringed Octopus Images

Diet: What Do Blue-ringed Octopi Eat

The BRO lives by primarily feeding on crabs, shrimps, and other invertebrates. However, it also consumes wounded fish, or else live, if it can catch them. They pounce on the prey and invade it with by its tentacles and pulling it towards their mouth. They then paralyze the prey by its venom while piercing its beak through the exoskeleton.

Mating and Reproduction

The blue ring octopus has strange sexual behaviors. The mating ritual of these creatures begins with the male approaching the female and caressing it with its modified arm – ‘hectocotylus’. After this, the male would climb onto the female, and at times would completely cover up the female’s mantle and obstruct the latter’s vision. The modified arm is then inserted into the oviduct of the female and spermatophores are released. The male octopus dies after mating.

The female octopus lays only a single clutch of eggs in her whole lifetime, with the clutch containing of about 50-100 eggs. The female protects the eggs under her arms for a period of almost six months. It dies soon after the hatchlings come out, since it does not consume any food during incubation.

Blue-Ringed Octopus Baby

Blue-Ringed Octopus Baby

Blue-Ringed Octopus Eggs

Blue-Ringed Octopus Eggs

Life Cycle of the Baby Blue-ringed Octopus

The hatchlings are born tiny, about the size of a pea. However, they grow very rapidly and are able to hunt for their own foods within a month’s time. They are sexually matured and active within a year and are able to mate by the following autumn. The ink sacs present in the other octopi exist in the juveniles of the species, but the sacs greatly reduce in size, as they grow older.


  1. Blue-ringed Octopi are immune to their own The venoms of other pygmy octopi are also not potent to these creatures.
  2. Other than the lethal weapon of their inbuilt poison, the octopus can camouflage itself with its surroundings as an effective defense mechanism.
  3. Their physical flexibility is also a big adaptation of these creatures. The criss-cross patterns of fibers that have built up their muscles enable them to squeeze through extremely small spaces, rock cracks, etc.

Blue-Ringed Octopus Bite

Blue-Ringed Octopus Size


The biggest predator of the blue ring octopus is the moray eel. Other predators also include whales, seals, and different types of shore and marine birds.

The BRO is also not safe from human predation. Owing to its bad reputation, these creatures, if found, are frequently killed by people.

Conservation Status

These animals have not been declared as ‘endangered’, but it is generally considered as threatened due to its loss of habitat. These creatures do not appear in the list of the IUCN.

Interesting Facts

  • The toxin of these octopi is created by a bacteria present in their salivary glands.
  • The soft tissues of the BRO are also extremely poisonous, if consumed.
  • Generally, rings are not visible (or are very faint) when they are at rest, but shows up especially when agitated. At this time, the brown patches darken extensively while the iridescent blue rings appear and pulsate within the maculae.
  • The creature has two poison glands that release two different types of poison in their saliva. One type is primarily effective against its prey, while the other is extremely toxic, which they use against predators for defense.
  • A blue-ringed octopus holds enough poison that is potent enough to kill 26 adult humans within minutes.
  • The mechanism for poisoning its victim is not yet understood clearly. There can be two possibilities: either the poison is expelled through the saliva into the water or else, the octopus itself bites its prey or predator.
  • The beaks of these octopi are so strong that, they can penetrate through a wetsuit.
  • Besides dolphins, the blue-ringed octopi are the only non-humans that enjoy the act of sex.
  • The act of copulation continues until the female has had enough, and in most cases, the female needs to use its force to pull down the over-enthusiastic male.
  • Male blue-ringed octopus displays homosexual behavior attempting to copulate with both the males and the females, and of all sizes. However, interactions between the males are most often shorter that ends with the mounting octopus withdrawing its modified arm without struggle or packet insertion.

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