Blue-ringed octopuses, comprising the genus Hapalochlaena, are four extremely venomous species of octopus that are found in tide pools and coral reefs in the Pacific and Indian Oceans, from Japan to Australia. They can be identified by their yellowish skin and characteristic blue and black rings that can change color dramatically when the animals are threatened. They eat small crustaceans, including crabs, hermit crabs, shrimp, and other small sea animals.

They are some of the world’s most venomous marine animals. Despite their small size—12 to 20 cm (5 to 8 in)—and relatively docile nature, they are very dangerous if provoked when handled because their venom contains a powerful neurotoxin called tetrodotoxin.

The species tends to have a lifespan around two to three years, which may vary depending on factors such as nutrition, temperature, and the intensity of light within its environment.

Behavior

Blue-ringed octopuses spend most of their time hiding in crevices while displaying effective camouflage patterns with their dermal chromatophore cells. Like all octopuses, they can change shape easily, which allows them to squeeze into small crevices. This, along with piling up rocks outside the entrance to their lairs, helps safeguard them from predators.

If they are provoked, they quickly change color, becoming bright yellow with each of the 50–60 rings flashing bright iridescent blue within a third of a second, as an aposematic warning display. In the greater blue-ringed octopus (H. lunulata), the rings contain multilayer light reflectors called iridophores. These are arranged to reflect blue–green light in a wide viewing direction. Beneath and around each ring are dark-pigmented chromatophores that can be expanded within one second to enhance the contrast of the rings. No chromatophores are above the ring, which is unusual for cephalopods, as they typically use chromatophores to cover or spectrally modify iridescence. The fast flashes of the blue rings are achieved using muscles that are under neural control. Under normal circumstances, each ring is hidden by contraction of muscles above the iridophores. When these relax and muscles outside the ring contract, the iridescence is exposed, thereby revealing the blue color.

Toxicity

The blue-ringed octopus, despite its small size, carries enough venom to kill 26 adult humans within minutes. Their bites are tiny and often painless, with many victims not realizing they have been envenomated until respiratory depression and paralysis begins. No blue-ringed octopus antivenom is available

The octopus produces venom containing tetrodotoxin, histamine, tryptamine, octopamine, taurine, acetylcholine, and dopamine. The venom can result in nausea, respiratory arrest, heart failure, severe and sometimes total paralysis, and blindness, and can lead to death within minutes if not treated. Death is usually caused by suffocation due to paralysis of the diaphragm.

Direct contact is necessary to be envenomated. Faced with danger, the octopus’s first instinct is to flee. If the threat persists, the octopus goes into a defensive stance, and displays its blue rings. If the octopus is cornered and touched, it may bite and envenomate its attacker.

Conservation

Currently, the blue-ringed octopus population information is listed as least concern according to the International Union for Conservation of Nature. Threats such as bioprospecting, habitat fragmentation, degradation, overfishing, and human disturbance, as well as species collections for aquarium trade, though, may be threats to population numbers. Hapalochlaena possibly contributes to a variety of advantages to marine conservation. This genus of octopus provides stability of habitat biodiversity, as well as expanding the balance of marine food webs.

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  • vovchik_ilich [he/him]@hexbear.netEnglish
    3·
    1 day ago

    Did they keep you waiting long at this Estonian border? My bus will drop me there in the early morning and I’ve seen that the queues go outside the building. I’m a Spaniard and I don’t wanna freeze to death lmao. Oh I’m talking about the Narva-Ivangorod crossing btw

    • unaware [they/them]@hexbear.netEnglish
      3·
      1 day ago

      The queue was so long, it lasted 7 hours! And it rained, so even if it was the summer, it was pretty cold! Thankfully some Russians who were travelling in the same buses decided to give vodka to everyone to keep us warm (I don’t drink under normal circumstances, but I made an exception there). Perhaps me being tipsy contributed to why I didn’t declare my cash properly lol. At least, once we reached the border itself (after the long queue), the crossing was rather quick.

      However, my bus dropped me at the border in the early afternoon, so I imagine that in your case there will be fewer people since you’ll arrive in the early morning. I was told before the crossing that it would last 4 hours, perhaps this is the time that you should expect to wait?

      • vovchik_ilich [he/him]@hexbear.netEnglish
        3·
        1 day ago

        Well, shit hahaha. I read that the queues in summer get long, but SEVEN HOURS!! I really hope nothing like that. Did you travel with Ecolines? If so, did the bus wait for you on the other side despite the super long border control, or did you have to pick another bus?

        • unaware [they/them]@hexbear.netEnglish
          2·
          1 day ago

          I travelled with Lux Express, simply because it’s the company I had heard of when I made my impulsive decision to go to Russia. We had to go to another bus that was waiting for us on the other side of the border (from what I understood it’s because the border was under repairs, so the bus couldn’t physically cross it; otherwise we would cross the border while on the bus, leaving just for the passport and baggage checks: this is what I did on the Kaliningrad-Gdansk bus that I took on the way back). The contrast between the two buses was actually very large: wifi, chargers, screens and coffee machine on the first one; not even chargers on the second one; so if your buses are similar, don’t repeat my mistake and do charge your phone in the first bus just in case!

          • vovchik_ilich [he/him]@hexbear.netEnglish
            3·
            1 day ago

            Thanks a lot! I’ll be coming back with LuxExpress, but Ecolines was cheaper for going there and the bus will be earlier, which is convenient. Regardless, even if the control was 7h long, the bus waited for you all?

            • unaware [they/them]@hexbear.netEnglish
              3·
              1 day ago

              Yes the second bus waited until all of us that had been in the first bus had passed border control. Since they were taking in batches of 20-ish people every time, he only had to wait for a few batches of people for everyone from our bus to pass through. I assume that the driver of the second bus knew of the length of the queue and probably didn’t wait for the entire 7 hours, but I didn’t ask.

              Also you’re right to take an earlier bus! Since mine arrived at the border around 14h00, we had finished the crossing at around 21h30, we arrived in St Petersburg not too far from midnight, so had I not found someone on the bus who agreed to exchange roubles for some of my euros, I wouldn’t have been able to exchange money in St Petersburg (the banks and whatnot were already closed)!