How do crawdads clone themselves?
Updated: Dec 13, 2021
In science fiction they call it gray goo - nanobots that replicate without limits until eventually everything on the planet is a featureless gray goo. It’s the first thing that came to mind when I read a recent article in the NY Times about a new species of crayfish that clones itself and is taking over Europe. The species emerged just 25 years ago as a mutation.
Normally, animals have two chromosomes, one from each parent. This female crayfish ended up with three, meaning that she could produce her own fertilized eggs without mating. And every egg is a perfect clone of the original crayfish. Oh, and crayfish lay hundreds of eggs at a time. More from the German Cancer Research Institute.
The crayfish were sold in pet stores in Germany, where they’re called marmorkrebs. People would buy a single crayfish and end up with dozens in just a few weeks. Instead of flushing them down the toilet, they’d release the extra crayfish into local ponds and streams, where they multiplied like crazy. And soon all of Europe will be nothing but marmorkrebs.
Actually, the new species has spread to other continents, including madagascar, where it threatens native crayfish species.
So the marmorkrebs were first discovered in 2003, but their genome was sequenced and compared to other crayfish until 10 years later and they weren’t officially named their own species until now. The marmorkrebs have been studied all over the world, but mostly by Frank Lyko at the German Cancer Research Center. Lyko and his colleagues are studying the marmorkrebs to see if they can reveal any secrets about how tumors form.
Tumor cells are genetic clones, yet they can adapt to resist medical treatments. It’s still a unclear how exactly they manage to do it, and Lyco hopes to learn something from studying the marmorkreb clones. You see, the crayfish clones do adapt to their environment over time, a processes called clonal evolution. Watching marmorkreb clonal evolution over time may help researchers learn how tumors adapt to resist treatment.
But what about the environmental impact of the marmorkrebs? Will they reproduce indefinitely until the planet is nothing but glossy gray exoskeletons and tiny pinchers? Perhaps, but not likely. About 1 in 10,000 species on the planet are female-only clones. It’s pretty rare, and clone species are probably pretty fragile. All it takes is one especially deadly virus and the entire species could be wiped out at once. Because there’s no genetic diversity, the chances of a single crayfish being able to resist the deadly virus is very slim. In fact, in the early 1900s the North American crayfish plague swept across Europe, decimating the local crayfish population.
The European Union banned the sale of marmorkrebs in 2016 and they’re banned in Missouri and Tennessee. However, and I really don’t suggest this at all, you can order your very own marmorkreb on Amazon. I’m not kidding, it’s right there with the headline:
1 Self-Cloning Marmorkreb Crayfish/Freshwater Lobster (Reproduces without a mate!) - 1+ Inch Juvenile by Aquatic Arts
Of course there is a warning in the description:
Please be advised that this crayfish will produce a great deal of clones, many of which will reach adulthood and also begin reproducing at the same rate. There’s also a warning about marmorkrebs being illegal in some states, but I don’t see any state-based restrictions imposed on the sale of marmorkrebs through Amazon.
So, yeah. Maybe the world will be nothing but marmorkrebs in 10 years. I hope they taste good.