A crustacean whodunit: which sea creature attacked an Aussie teen?

by Greg Mayer

Appropriately following upon Jerry’s monstrous, triffid-like seed pod,  an attack by tiny monsters on an Australian teenager has been splashed across world media, including the BBC and the New York Times. The victim, Sam Kanizay was cooling off after a football match by wading in the sea near Melbourne. After a half hour in the water, he emerged bleeding profusely from the ankles, and the bleeding did not readily stop. He was taken to the hospital and should be just fine.

Sam Kanizay being treated in hospital. Photo by Jarrod Kanizay, via Australian Associated Press.

The interesting question from a biological point of view is “What did this to him?” We have a natural history whodunit, with two contenders, both crustaceans, and both quite small: isopods or amphipods. The BBC, citing Genefor Walker-Smith, said it was amphipods. The Times said the consensus was that it was isopods. Sam’s father Jarrod put some meat out in the water, and collected a host of critters, and posted a video of them to Youtube.

Most people in the north temperate zone are probably familiar with what we call in New York “cement bugs”, but are known by many other names: sow bugs, pill bugs, rollie pollies, etc. These are isopods, and there are marine ones called sea lice. Amphipods are less familiar in the Northern hemisphere, as they are aquatic and marine, and thus less commonly encountered. (There are terrestrial ones in the Gondwanan continents.) The ones that live at marine beaches are called sand fleas. One way to tell at least the usual ones apart is that isopods are dorso-ventrally compressed (‘squashed’ from above); while amphipods are laterally compressed (‘squashed’ from the side), and typically lay and move about lying on their sides. Both are said by the news reports to occasionally bite people.

In the video, you can clearly see that the critters are amphipods– pause the video, and enlarge on the screen if necessary, to see this. The Times quotes Alistair Poore, of the University of New South Wales, as also saying the critters are amphipods. However, although Jarrod trapped them by using meat as a bait, it’s not certain that what he trapped are the same things that bit Sam.


  1. ThyroidPlanet
    Posted August 7, 2017 at 12:54 pm | Permalink


  2. Posted August 7, 2017 at 12:59 pm | Permalink

    Fine tuned for us, my ass. The ocean has tiny little flesh eating bugs! I’m getting the heeby jeebies just reading about it!

    • Diana MacPherson
      Posted August 7, 2017 at 1:23 pm | Permalink

      The Australian ocean is deadly. It’s like the Cambrian there!

      • infiniteimprobabilit
        Posted August 7, 2017 at 9:18 pm | Permalink

        Let’s see now, sharks, sea snakes, sea wasps, blue ringed octopus, crocodiles, stone fish, crown of thorns starfish, cone shells, poisonous sea slugs, lion fish, fugu fish / porcupine fish – have I left anything out?

        (And that’s only the delights that await you in the water, there’s a whole range of interesting beasties once you step onto land 🙂

        Oh yes, rays, but only if you’re called Steve.

        • Diana MacPherson
          Posted August 7, 2017 at 10:04 pm | Permalink

          I wouldn’t be surprised if there was a mosasaur in the ocean there.

          • infiniteimprobabilit
            Posted August 8, 2017 at 12:15 am | Permalink

            Mosasaur (Googles…) Oh my gods, look at the jaws on that thing!

            I didn’t think a skeleton could look insanely, rambunctiously crazy but that damn thing does.


            • rickflick
              Posted August 8, 2017 at 6:33 am | Permalink

              They don’t create ’em like that anymore.

              • Posted August 8, 2017 at 6:56 am | Permalink

                In the 60s we had the idea to emigrate to OZ, but when the missus learned that there are more things that can kill you in OZ ,than anywhere else on the Planet,well,we are still in the UK.

              • Diana MacPherson
                Posted August 8, 2017 at 11:43 am | Permalink

                I worked with a guy from Thailand. I asked him why he chose Canada to emigrate too. He said that he had the choice between Canada & Australia & chose Canada because Australia had too many big spiders. And he is from Thailand!!

        • Posted August 8, 2017 at 11:37 am | Permalink

          Portuguese man-o-war?

          • infiniteimprobabilit
            Posted August 8, 2017 at 11:06 pm | Permalink

            Oh yes, that too. Also known as ‘bluebottles’, apparently, in Oz (a source of confusion as a ‘bluebottle’ in England is a fly).


    • rickflick
      Posted August 7, 2017 at 9:17 pm | Permalink

      Don’t go in without a wet suit, hood, booties, and gloves. And a full face mask.

      • busterggi
        Posted August 8, 2017 at 10:24 am | Permalink

        Just don’t go in.

    • Posted August 8, 2017 at 3:15 am | Permalink

      It is also full of drowned sailors 😦

      • infiniteimprobabilit
        Posted August 8, 2017 at 4:59 am | Permalink

        It would be, but the bugs have conveniently eaten them all.


  3. Michael Fisher
    Posted August 7, 2017 at 1:41 pm | Permalink

    The interesting part for me is the dad reported that his son’s shins wouldn’t stop bleeding from these pinprick bites.

    So, taking that remark as true – that might help identify the mini-muggers. What marine parasites deliver an anticoagulant with their toothsome insults on human flesh? I know some crustacea do, lampreys do & Cymothoidae [isopods] do…

    • gravelinspector-Aidan
      Posted August 7, 2017 at 6:12 pm | Permalink

      I suspect that any organism that lives in by “blood-sucking” lifestyle is going to benefit by having mouth juices with an anti-coagulant effect. You can add leeches to your list. Mosquitoes too. I’d be damned surprised if ticks (a big group) didn’t include many representative compounds too.
      Whether research into the ecology and biochemistry of the relevant (I don’t think “guilty” is appropriate here) organism has previously identified mammalian-effective anticoagulants is .. pretty close to chance.

    • Torbjörn Larsson
      Posted August 7, 2017 at 7:57 pm | Permalink

      “Walker-Smith speculated that the ones that attacked Sam may also possess an anti-coagulant, similar to peptides used by leeches. That may explain Sam’s excessive bleeding after the attack. An anti-coagulant combined with the low water temperatures may also explain why Sam didn’t feel the feeding frenzy at his feet.”

      “It’s still unclear what caused them to swarm around Sam’s legs, though. Earlier research has suggested that lysianassid amphipods may have two strategies for flesh foraging: passively “hovering” until they sense an attractive chemical plume from flesh, or lying low in sediment until a body falls in their midst. Walker-Smith speculated to local media The Age that Sam may have inadvertently gotten too close to a fish carcass on which the fleas were feasting.”

      [ https://arstechnica.com/science/2017/08/australian-teen-chewed-and-bloodied-after-bizarre-ocean-feeding-frenzy/ ]

      • infiniteimprobabilit
        Posted August 7, 2017 at 9:27 pm | Permalink

        We often get sand hoppers (‘sand fleas’) on the West Coast here (Auckland NZ). They seem to frequent washed-up seaweed, sometimes the area round a half-buried frond of kelp is alive with them. The biggest might be half an inch long. I’ve never noticed them bite me though.

        I think they’re probably talitridae

        It could be that the offending critters are a related species.


  4. busterggi
    Posted August 7, 2017 at 2:13 pm | Permalink

    So he didn’t notice that he was being eaten alive until after he got out of the water????

    I usually notice things like that.

    • Michael Fisher
      Posted August 7, 2017 at 2:20 pm | Permalink

      Just like some insect bites – no signal to the brain of the host

    • Nick
      Posted August 7, 2017 at 3:22 pm | Permalink

      The water was very cold and I heard somewhere that he felt tingling but thought it was just his skin and muscles’ reaction to the water.

      • Torbjörn Larsson
        Posted August 7, 2017 at 7:52 pm | Permalink

        If I feel tingling and can’t see the skin area, I evacuate. Better safe than sorry.
        (Yes, I have trouble swimming in dark waters, but not so much just floating there.)

    • Rita
      Posted August 7, 2017 at 6:35 pm | Permalink

      We used to swim in a lake when we were kids, and if we got too close to the weeds, we would emerge with leeches on our ankles. We didn’t feel them, we always had to look for them.

      • infiniteimprobabilit
        Posted August 7, 2017 at 9:39 pm | Permalink

        Urrgh. Leeches. Just the thought of them gives me the creeps.

        Does Australia have leeches? (Googles) OK, ask a silly question…


        • Diana MacPherson
          Posted August 7, 2017 at 10:10 pm | Permalink

          When i as a toddler I got leeches all over my feet. My dad put salt on them.

          • rickflick
            Posted August 7, 2017 at 10:27 pm | Permalink

            Salt. A little pepper. Some butter…

        • loren russell
          Posted August 8, 2017 at 2:34 am | Permalink

          ip: In Queensland you definitely have land leeches. That is, they live in trees and land on you. Umbrella recommended,

          • infiniteimprobabilit
            Posted August 8, 2017 at 5:01 am | Permalink

            Better and better…


      • Hempenstein
        Posted August 9, 2017 at 7:46 am | Permalink

        Besides the anticoagulant, they likely produce a local anaesthetic peptide of some sort. Plenty of examples of those among the cone-snail toxin peptides that target all sorts of neurotransmitter receptors.

  5. Posted August 7, 2017 at 2:22 pm | Permalink

    Curious also is the fact that he seems to be the only one attacked. I read reports earlier today that others had been swimming at the same location without being attacked.

  6. ploubere
    Posted August 7, 2017 at 3:26 pm | Permalink

    It’s an illusion that we are the dominant species.

  7. Gamall
    Posted August 7, 2017 at 3:30 pm | Permalink

    Just what I needed to see before going to bed. Thanks, Prof. Ceiling Cat.

  8. Kevin
    Posted August 7, 2017 at 3:53 pm | Permalink

    OK. Snakes, spiders, sharks, gators, heart stopping jellies, and now flesh eating critters. I am never going to Australia. The land where evolution has made some tough animals.

    • infiniteimprobabilit
      Posted August 7, 2017 at 9:35 pm | Permalink

      It’s the cute ones you really have to watch out for. Cuddly Koala bears that will try to chew your leg off. Quaint duck bill platypus that are among the few poisonous mammals. Flightless cassowaries that can run much faster than you can and will try to rip you to shreds with their claws. Kangaroos that will disembowel you with those big back legs.

      Australia – the place where all the wildlife deeply, sincerely hates you. 😉


  9. Posted August 7, 2017 at 5:17 pm | Permalink

    Great. Now the next craze for youngsters who dare and double-dare each other to do dangerous things is to ‘take the amphipod challenge’.

  10. BJ
    Posted August 7, 2017 at 5:41 pm | Permalink

    Damn, Australia, you scary!

  11. Posted August 7, 2017 at 5:43 pm | Permalink

    Reblogged this on The Logical Place.

  12. Posted August 8, 2017 at 11:39 am | Permalink

    People are often allergic to some component or other of insect “bites”. Is that likely the case here too?

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