Marbled crayfish have developed the ability to self-clone – and now a million-strong crustacean army exists in waters stretching from Europe to Japan

Name: Marbled crayfish. Marmorkrebs in German.

Age: Potentially infinite.

Appearance: Marbled, to be blunt.

Right, so it’s a potentially infinitely old crayfish with a marbled appearance. Got it. Not so fast. There’s something interesting about this potentially infinitely old marbled crayfish.

Is it to do with the marbling? The infinity, actually. For this is a self-cloning crayfish.

Parthenogenesis is the technical term, I think you’ll find. Correct. And the crayfish bowled over scientists when it was first discovered in the early 2000s. The entire clone army – now in the millions – is descended from one bag of Texas crayfish a German aquarium enthusiast bought online from a US trader in 1995.

Who is this curious mogwai merchant? Is he still selling them? Definitely not. They are banned in the EU.

Mutant, all-female crayfish spreading rapidly through Europe can clone itself Read more

They’re the laser-pointers of decapod crustaceans? The problem is that they’re taking over. The species has shown up in the wild in Germany, Italy, Slovakia, Sweden, Japan and Madagascar.

Isn’t that evolution in action? It’s pretty destabilising when you consider that, in the past 10 years, they have expanded 100-fold in Madagascar. They are less successful in colder Germany, but the fact that they can survive as far north as Sweden suggests a rugged nature.

Yikes. What’s inside these succulent replicants? Unfortunately, these are part of the “dwarf” half of the crayfish family tree, and so are less delicious than their bigger cousins. But that still hasn’t stopped the Madagascans developing quite a taste for them.

But at a genetic level? Do we have any clues? Scientists have sequenced their entire genome. Crayfish differ from one another by maybe four letters in a DNA strand of 3.5bn letters. Plus, they have three sets of chromosomes. Almost all other animals have two: a mother’s and a father’s.

But why has that happened? Chance, so far as anyone can gather. But huge odds. Some species dabble in parthenogenesis: Komodo dragons, velvet worms, zebra sharks, New Zealand mud snails. But this is the first time such a leap has been observed in real time.

Can anything be done? Do we just need to welcome our new insect overlords? Well, in terms of evolution, parthenogenesis is much less common because, over the extreme long term, it doesn’t allow for as much adaptation through mutation. Clone species tend to die out when the environment changes.

So we just have to wait a few million years? Problem solved.

Do say: “Never feed a marbled crayfish after midnight.”

Don’t say: “Why hasn’t evolution coated them in butter and garlic?”