The Mutant All-Female Crayfish, Which Reproduces by Cloning Itself, Is Filling Europe at Alarming Speed

The marbled crayfish looks much like any other freshwater crustacean. It has two claws, ten legs, and an attractive blue-brown marbled shell. Yet this six-inch creature, found in streams and lakes around the world, is far more sinister than you might expect. From a report: Its new scientific name gives a few clues: Procambarus virginalis. Every marbled crayfish, known as a marmorkreb in German, is female -- and they reproduce by cloning themselves. Frank Lyko, a biologist at the German Cancer Research Center, first heard about the marbled crayfish from a hobbyist aquarium owner, who picked up some "Texas crayfish" at a pet shop in 1995. They were strikingly large, and they laid enormous batches of eggs -- hundreds, in a single go. Soon, the New York Times reports, the hobbyist was beset with so many crayfish he was giving them away to his friends. And soon after that, marmorkrebs were showing up in pet stores upon Europe. There was something very strange about these crayfish. They were all female, and they all laid hundreds of eggs without mating. These eggs, in turn, hatched into hundreds more females -- with each one growing up fully able to reproduce by herself. In 2003, scientists sequenced their DNA and confirmed what many owners already believed to be the case: Each baby crayfish was a clone of its mother, and they were filling Europe's fishtanks at alarming speed. Just 25 years ago, the marbled crayfish did not exist at all. Now, they can be found in the wild by the millions in Germany, the Czech Republic, Hungary, Croatia, the Ukraine, Japan, and Madagascar.