Of the 300-plus octopus species that are currently in existence, the blue-ringed octopus receives, a lot of attention. The main reason for this is due to the fact that it is the only octopus that is deadly to humans.
While that fact definitely has shock value, the blue-ringed octopus is interesting for a variety of other factors as well. If you are curious about all facets of this octopus, please, read on.
Blue-Ringed Octopus Facts
- Scientific Name : Hapalochlaena
- Common Name: Blue-Ringed Octopus
- Size: 12 to 20 cm (5 to 8 in)
- Weight: 25 – 30 grams
- Lifespan: 2 years
- Found in: Pacific – Indian oceans
- Sub-Order: Incirrina
- Discovered: 1929
- Scientific Name : Hapalochlaena
- Common Name: Blue-Ringed Octopus
- Size: 12 to 20 cm (5 to 8 in)
- Weight: 25 – 30 grams
- Lifespan: 2 years
- Found in: Pacific – Indian oceans
- Sub-Order: Incirrina
- Discovered: 1929
The blue-ringed octopus receives a lot of attention. The main reason for this is due to the fact that it is the only octopus that is deadly to humans.
—Background on the Blue-Ringed Octopus—
The term “blue-ringed octopus” is the popular name used to refer to this marine creature. In reality, when people refer to the blue-ringed octopus they are talking about octopuses belonging to the genus Hapalochlaena.
“Genus” is the term used in the classification of living creatures. It is one notch above species. It accommodates a group of species of a similar origin. The species composing a genus share very similar characteristics. An example that you should be familiar with is the genus Felis. This includes all cats such as lions, tigers, cougars and your housecat. All different species but sharing a similar body style, characteristics and lifestyle.
In the case of the blue-ringed octopus, the genus Hapalochlaena is comprised of four octopus species. These are:
- First: Hapalochlaena lunulata, better known as the “greater blue-ringed Octopus.”
- Second: Hapalochlaena maculosa, also known as the “southern blue-ringed octopus.”
- Third: Hapalochlaena fasciata, commonly known as the “blue-lined octopus.”
The final entrant is Hapalochlaena nierstraszi . This species does not have a common name. Since it was first discovered in 1938, only two specimens have ever been caught. This means that little is known about them and few people have actually seen one. Some marine biologists speculate that the species may be more reclusive than the other three and with much shorter natural life spans. The second and last specimen of this species that was caught occurred in 2013.
In this article, we will be talking about the “blue-ringed octopus” the way marine life enthusiasts do. In other words, we will be making reference to the genus as a whole, encompassing all four component species. This is less confusing since all share similar traits and habitats.
—Physical Characteristics—
Blue-ringed octopuses are relatively small creatures. The southern blue-ringed octopus is the largest of the bunch growing to a length of eight inches. The other constituent species grow to four and two inches.
The blue-ringed octopuses are members of the incirrina group of octopuses. This means that they do not have a semi-rigid shell structure within their head. For that reason, they have the classic octopus shape. Large bulbous heads without any fins attached to the sides. They have eight arms lined with suckers.
—What Makes The Blue-Ringed Octopus Stand Out From the Crowd?—
Being small and sporting a common octopus shape, you may think that this type of octopus would be boring to look at. That would be a huge misconception.
Aside from its toxicity, the other factor that makes the blue-ringed octopus so intriguing is its coloration. When these octopuses are going about their normal daily routine their coloration is not noticeable. Like other octopuses, they have an excellent ability to camouflage themselves by matching the color and pattern of their background. If you were to come across one of them in this state you may not even notice it.
However, when the blue-ringed octopus becomes agitated or feels that it is in danger it will literally begin to shine. Its skin will take on a yellow to orangish color. The blue-ringed patterns distributed throughout its body (for which it gets its common name) become distinct. If the octopus feels the danger is increasing it will make its blue rings reflect light to make them appear as shining — some would say flickering.
—How Do They Do It?—
They are able to do this because the structure of the skin cells which make up the ring shapes contain iridophores. These can be manipulated by minute muscle movements to reflect light. More specifically, light on the blue and greenish end of the spectrum. This type of behavior is known more broadly as aposematism. It refers to any behavior by an animal designed to draw attention to itself to warn other animals that they are messing with the wrong dude.
It is the biological equivalent to trash talking to your opponent in the hopes that they will back down. In other words, the bright coloration and reflective display of the rings are meant to scare away attackers.
This defensive tactic has been observed to scare away potential predators much larger than the blue-ringed octopus.
—Blue-Ringed Octopus Behavior—
The blue-ringed octopus is a very mild-mannered creature. Even though it packs a lethal venom, it never goes out looking for trouble. It prefers to stay out of view. For the most part, when they are not hunting for prey, they will be in crevices between rocks or coral on the ocean floor. They commonly place rocks — which they gather themselves — at the entrance of their dwellings to secure them further and gain even more privacy. When exposed they will apply their camouflaging technique to blend into the surroundings.
If anything, blue-ringed octopuses are shier than other species. Compared to the octopus Vulgaris, the blue-ringed octopus is a total introvert. They display little curiosity in approaching other creatures unless they are prey.
—Hunting and Feeding—
The blue-ringed octopus is a very effective hunter. The majority of its diet is composed of small crustaceans, such as shrimp and crabs. larger specimens, those longer than four inches, have been observed to also catch and eat injured fish.
The blue-ringed octopus utilizes a style of hunting that is known as the “pouncing” technique. This means that the blue-ringed octopus prefers a shorter pursuit of its prey. They will slowly approach their prey in order to go undetected for as long as possible. Better still, when practical, they lay in wait for unsuspecting prey to come within attacking distance.
Once their prey is in the “kill zone,” the blue-ringed octopus will use a burst of speed to attack it from above. It will position its arms around the prey. Its suckers clinging hard to the animal. It then uses the muscle power of its arms to draw the prey to its mouth.
The Blue-Ringed Octopus' Mouth and Beak
Located at the base of the octopus’ head, at the center of where its eight arms extend from, the mouth of the blue-ringed octopus has a beak. This beak is the only hard part of its body. It is composed of chitin. In nature, chitin is also found in the exoskeleton of arthropods. It can create strong and solid structures.
The beak of the blue-ringed octopus is composed of two parts. Acting in tandem, they can perform shearing-like actions as well as serving as a lance.
When the octopus brings its captured prey to its mouth the first thing that it does is pierce the creature with its beak. It then unloads a dose of its deadly toxin. Almost immediately, the captured prey enters a state of paralysis. With its prey unable to move, the octopus then funnels digestive juices into the prey’s body. This helps to soften up the meat for extraction.
The beak can then be used to open the crustacean in order to suck out its tender insides. When finished, the blue-ringed octopus discards the empty shell to the ocean floor.
—Toxicity of the Blue-Ringed Octopus' Venom—
It is important to state that all octopuses are venomous. They all use a style similar to that of the blue-ringed octopus in immobilizing their prey and preparing it for consumption. In that regard, the blue-ringed octopus is just “one of the gang.”
What makes the blue-ringed octopus stand out is that its toxin is the only one lethal enough to kill a human being. If you were to be bitten by another octopus of similar size to a blue-ringed octopus you may not even notice it. A large octopus may create a painful puncture-like sensation similar to stepping on an exposed nail or staple. All, however, would be survivable and free of lingering side effects.
The blue-ringed octopus’ venom, however, will paralyze your respiratory system and you would suffocate to death. It is even scarier when you learn that there is no antivenom for it. If you get bitten, the best that can be done for you is to treat you with stimulants to keep you breathing and your heart pumping in the 24 to 36 hours that it takes for the venom to clear your system.
If you are not treated in time or if your body’s respiratory system cannot be stimulated to keep functioning, you will die.
Characteristics of the Venom
The toxin of the blue-ringed octopus is composed of the same substance as the toxin of another deadly creature of the sea —the pufferfish. This substance is known as tetrodotoxin.
The blue-ringed octopus does not produce this deadly substance directly. The salivary glands of the octopus provide an environment conducive to a specific type of bacteria to thrive. This bacteria, in turn, produces the deadly substance. It is the ultimate “work for rent” agreement.
Tetrodotoxin is 1,200-times deadlier than cyanide. Even though the area of production resides within the octopus’ salivary glands, it is present throughout its body —including the hearts and gills. When females lay eggs they inject it into their unhatched eggs in order to “seed” their own production of the substance. Essentially, they are injecting seed colonies of the bacteria that produce it. This way they can form a symbiotic relationship with the unhatched octopuses so that they will be able to hatch as deadly blue-ringed octopuses in their own right.
—Blue-Ringed Octopus Reproduction—
The mating process for blue-ringed octopuses follows a very similar pattern to other incirrate octopuses from warm and shallow water habitats. The male approaches a female and begins its “mating dance.” This involves caressing the female and grabbing her with his arms. The process can seem awkward to observers. The males sometimes end up on top of the females heads.
One of the arms of the male blue-ringed octopus is called the hectocotylus. It is designed to transfer clusters of sperm in the form of packets and place them inside the female. Since octopuses lack dedicated genitals, the male uses his arm to deliver sperm inside the mantle cavity of the female’s head.
Yes, this sounds very awkward but it has worked for octopuses for over 500 million years.
Female blue-ringed octopuses lay only 50 eggs. They carry them underneath their arms and incubate them for six months. Once the hatchlings emerge, the mother octopus will die shortly afterward.
The lifespan of a blue-ringed octopus is one to two years. They reproduce only once before dying.
—Locomotion—
The blue-ringed octopus can crawl and walk along the ocean bottom using its arms as legs. They can also glide through the water head first. In moments of danger when speed is of the essence, the blue-ringed octopus can push water through its funnel to create a jet stream.
—Where Are Blue-Ringed Octopuses Found?—
The four species that comprise the genus known as the blue-ringed octopus live in the Pacific and Indian Oceans. They are primarily found near coral reefs and tidal pools. This means that they live near coastal regions and not in deep water areas further away from land. They can be found from Japan down to Australia. This includes coastal regions of the Philippines and Indonesia.
—Conservation Status—
None of the species of the blue-ringed octopus genus have been declared to be endangered. They are not part of organized fishing efforts since they are not an octopus species commonly associated with food preparation.
Their habitat is so expansive that as a whole, they do not seem to be under any environmental pressures either.
—The Blue-ringed Octopus as a Pet—
Many reckless collectors find the idea of adopting a blue-ringed octopus as a pet very intriguing due to its lethal nature. Import demand in the U.S. has grown steadily in recent years, rocketing from just 11 imports in 2004 to the amazing number of 1.148 in 2011.
On the one hand, it is understandable that this small, beautiful, colorful octopus may seem a very appealing choice for a pet owner. On the other hand, handling an octopus is challenging enough on its own. If you add deadly venom to the process, the situation might become pretty sticky. We do NOT, therefore, recommend keeping a blue-ringed octopus as a pet, especially if you have children in the house.
—In Summary—
The blue-ringed octopus is a shallow water octopus measuring no more than eight inches in length. Sporting a bright yellow skin with a pattern of blue rings throughout its body, it is very distinguishable.
The only octopus to be deadly to humans, it is found in and near coastal reefs and tidal pools in the Indian and Pacific Oceans.
Comprised of fours species, much is still being learned about this magnificent creature.
