Mary’s Monday Metazoan: The feminist crayfish

What else can you assume they are? The marbled crayfish are triploid, they’re all female, they only produce daughters, and they’re taking over the world.

Before about 25 years ago, the species simply did not exist. A single drastic mutation in a single crayfish produced the marbled crayfish in an instant.

The mutation made it possible for the creature to clone itself, and now it has spread across much of Europe and gained a toehold on other continents. In Madagascar, where it arrived about 2007, it now numbers in the millions and threatens native crayfish.

I don’t know whether to bow down before our new crustacean masters or prepare for an awesome crawfish boil.


  1. Callinectes says

    If they threaten ecosystems due to human introduction, then it is a conservation issue. But if a new species showed up and threatens others all by itself, is it our responsibility to intervene, or to not intervene?

    I would suppose the answer comes down to how broad the impact is, and whether it will negatively impact the lives of local people.

    I understand that this one is once again in some way a human clusterfuck, but as a general rule?

  2. unclefrogy says

    wow sounds like it might even be a new subject for aqua-culture
    I wonder how efficient it is as a producer of pound of protein to pounds of feed and what kinds will they eat?
    Mudbugs are not very particular
    crawfish are much lighter and sweeter than lobster shrimp or crabs.

  3. lotharloo says

    These Crayfish are basically kind of lobsters and per Jordan B Peterson we know that humans are basically kind of lobsters too so I guess it shows humans should form a matriarchal society. Someone tell him! Quick!

  4. Derek Vandivere says

    Ah, but wouldn’t a truly feminist crayfish produce female offspring empowered to make their own choices, rather than simple clones?

  5. davidc1 says

    Have they arrived in GB yet ? Does this mean they will not evolve ,seeing they are clones ?

  6. Edward Black says

    It’s a very interesting tidbit,, PZ but I have to say I am a bit uncomfortable with the title you chose.

    “The feminist crayfish”
    “What else can you assume they are? The marbled crayfish are triploid, they’re all female, they only produce daughters, and they’re taking over the world.”

    Really, that’s the standard NRA fantasy of the hideous “feminist” femnazi’s out to wipe all righteous defenseless males. I was a bit surprised to find you giving air to the mene/concept.

  7. Onamission5 says

    Edward #13: Right, I think that’s the joke. Vagenda of Manocide, crayfish version, aka any accusation from one’s opponent that is so ludicrous one immediately dons it like a mantle.

    Psst, I think you meant MRA, not NRA. One is a group of men so threatened by not having total power they are willing to lie, threaten, buy politicians, and commit violence while wearing the mantle of victimhood, and the other is…. um… well there’s a lot of overlap actually.

    Carry on.

  8. KG says


    They will evolve – mutation and selection still work – but going on what’s happened in the past, they won’t last indefinitely. For reasons that are not entirely clear – although failure to evolve fast enough to keep up with the evolution of parasites is a widely-favoured explanation – populations with obligate asexual reproduction don’t seem to last indefinitely. The big exception is the group of bdelloid rotifers which, very unusually, appear to routinely acquire large amounts of DNA from bacteria, fungi and plants, which may compensate.

    The marbled crayfish, however, might well last long enough to drive other crayfish to extinction. So to respond to Callinectes@5, where they have been introduced by people, as I imagine must be the case in Madagascar, we probably have an obligation to exterminate them if possible – but it almost certainly isn’t.