Every Octopus Is Venomous

“The more hidden the venom is, the more dangerous it is.” —Margeurite de Valois

In A Nutshell

While they seem harmless enough, every known species of octopus and cuttlefish, and some species of squid, are venomous.

The Whole Bushel

If you have ever picked an octopus up from the water’s edge and felt a small nip, you were right in thinking it bit you, but you may not have realized it was also giving you a shot of venom. The discovery that all octopuses and cuttlefish are venomous is very recent. In 2009, Australian scientists investigating how several species of octopus killed shellfish realized they were using venom. They spread their inquiries further and soon found every species they looked at was the same.

The venom itself is very similar to fugu and some snake neurotoxins, though obviously much milder. Also, snakes inject their venom, octopuses don’t. They use their beaks to drill holes into crustacean shells then deposit (“spit” is the less scientific word) a dose. It may not take much to knock out a sedentary mollusk but some carry their own arsenal of self-defense weaponry so a bit of venom helps.

The only species known to be dangerous to humans is the blue-ringed octopus found in the southern Indian and Pacific oceans, particularly around Australia. With its arms extended, a large one is about the size of a tea saucer and it lives on coastal reefs where its mottled appearance disguises it perfectly. Only when it is challenged does it show off its pulsating, bright blue rings. There is no antivenom but deaths are rare: just three have been recorded in the last century. The most common symptom is severe paralysis.

The relative mildness of other octopus venom explains why it remained unknown for so long. The bite from even fairly large octopuses is innocuous and usually has no visible effect, so the notion it could be injecting venom would have sounded far-fetched. Octopuses also have a reputation as one of the gentlest creatures on the seashore, bothering no one as they lie about in the shallows.

There are about 300 species of octopus known to us, ranging in size from the Wolfi, barely a centimeter long, to the giant Pacific, which can have a span of four meters (13 ft). New species of octopus are being discovered every year, which is excellent news. Medical scientists are especially happy. Animal venom is being used in drugs to treat cancer, diabetes, hypertension, and a range of other diseases, so discovering the octopus venom is like walking into a liquor store and finding a wall of beers you’d never heard of. Of course it also means that one day we may have to reclassify the blue-ringed octopus as the second most dangerous cephalopod.

Show Me The Proof

All Octopuses Are Venomous: Could Lead To Drug Discovery
All Octopuses Are Venomous, Study Says

  • Hillyard

    Not just venomous, but creepy.

  • EliGabriel

    Great. We find out that they’re intelligent, now we discover that they’re also venomous. What’s next? That they can drive a car and have a secret taste for human flesh? One more reason for me to lock the door, then.

    Saw a documentary about them once (on NatGeo Wild, I think). They seem to be self-aware (they can recognize themselves in the mirror). They can also do simple tasks, and retain the solution to simple problems. (In the show, they were given all sorts of jars to open–jars that only open when you twist them clockwise or counterclockwise. The octopus in the tank was able to open the jars after much trial and error, and easily remembered how to do it the next time. What’s scary though is they had a bunch of other octopuses (octopi?) watch from another tank. When these dudes were given similar jars, they too opened the darn things like they’ve been doing it all their lives. Yes, ladies and gentlemen, they can learn how to do things just by observing. (So move that octopus tank away from the TV, unless you want them to learn how to beat you at Mortal Kombat.)

    The biologists in the show then followed up the experiment by teaching the octopus word association. Yes, the bastards can learn language, too (though not in the way that we do it). Really, all the scientists have to do is teach them how to fire a gun and that’ll be the end of all of us. (They can navigate mazes easily, and squeeze through holes the size of a penny, so they can probably find your home in no time.)

    The show actually ended with a question (What would happen to the octopus with another thousand years’ worth of evolution?) and a CGI scene where gun-toting octopuses (no kidding) emerge from the sea to conquer the surface. Lucky for me, my health insurance doesn’t cover me beyond 2050.

    • inconspicuous detective

      have you ever watched the show that aired on discovery about the future of earth without humans? it’s set about 2 million years after or something, birds are like walrus, spiders are huge, turtles are the size of sauropod dinosaurs, and squid have become the new most intelligent species. it’s crazy, but they really are that smart.

      • EliGabriel

        Yeah, History has a similar show, but what really comes to mind is Lovecraft and all the comic book writers who mined the Cthulhu mythos–Alan Moore and Mike Mignola, in particular. “The Old Ones are coming! The Old Ones are coming!”

        • inconspicuous detective

          never bothered with those books and i doubt i ever will. regardless…i agree the tentecaled monsters from the deep are smarter than people think.

          (spelling errors are present, forgive me i’ve yet to sleep and it’s 5 am)

    • Mabel

      I don’t like to eat them because of these things. They’re just too smart and cool. Squid, however, are still fair game (and delicious).

      Just don’t tell me shrimp are this smart, because I love them on pasta.

    • 0_0

      Sounds like you probably watched “Aliens of the Deep”, which is an excellent documentary. They show studies that prove their ability to learn through observation alone, and also retain memories so that they can solve puzzles they’ve encountered before very quickly. As if their appearance weren’t alien enough, their anatomy is like no other animal that we know of. Three hearts and 9 brains. More accurately, they have one central brain in their “head”, and a cluster of neurons partway down each of their 8 arms. It’s believed that each arm thinks and operates independently. Each specializes at certain tasks, with some crossover. It’s an amazing creature!

  • EliGabriel

    One more thing: I sampled octopus tentacles one time from a stand with a Japanese name I can’t remember now. The tentacles were rolled into balls of flour, so you wouldn’t actually feel you’re eating one of the Old Ones. The thing was okay, although I doubt if I’m ever gonna try it again after reading this (or seeing that picture above).

    By the way, are the authors here paid like in Listverse, or do they write here pro bono?

    • Codeman

      This is called “takoyaki”

  • J_Doe5686

    Well, now I want a blue-ringed octopus as a pet!

  • rhijulbec

    What amazing, fascinating creatures!

  • Jack Shen

    These guys are like the Houdini’s off the sea, from some of the videos and articles I’ve browsed. Apparently what determines how small a hole the creature can fit through is the bony area around the beak and eyes.It’s the only part of the body it can’t compress.

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