New crayfish that doesn't need males to mate becomes all-powerful

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Image captionInvasive marbled crayfish are sold on Canadian online adverts for as little as C$0.50 (£0.28)

A new species of all-female crayfish able to reproduce without males is multiplying rapidly and invading ecosystems across the world.

A new study found that the marbled crayfish is descended from a single female with a mutation that allows it to reproduce by itself.

The self-cloning creatures are for sale in Canada, despite a warning against keeping the pests as pets.

The ten-legged mutant is already banned by the European Union.

Procambarus virginalis did not exist three decades ago but they have now been found in the wild in Japan, Madagascar, Sweden and the US.

A new study published in Nature, Ecology and Evolution describes the invasive species as a threat to wild ones, including seven native species in Madagascar.

"If you have one animal, essentially, three months later, you will have 200 or 300," Dr Wolfgang Stein, one of the researchers, told Canadian public broadcaster CBC.

Curiously, by studying the freshwater crayfish's successful ability to self-clone, scientists may be able to better understand how cancer spreads.

The crustaceans can be bought in some pet shops in Canada and through online adverts. One online seller offered a one-inch self-cloning marbled crayfish for free and five larger ones for C$20 ($16; £11.50).

While there is not yet a wild population of marbled crayfish in Canada, the department of fisheries and oceans warned that it would be illegal to release any unwanted crayfish into the wild.

"Based on what is known about the reproductive behaviour of the marbled crayfish, we do not recommend Canadians keep these animals as pets," Becky Cudmore, of the fisheries and oceans department, told CBC.

Mutant crayfish: What's the background?

It all started in an aquarium in a German pet shop in the 1990s. A female slough crayfish, a species originally from Florida, was born with an additional set of chromosomes - a mutation that allowed her to reproduce without having to mate.

Her offspring and their spawn could produce hundreds of eggs at a time.

Media captionCrayfish take over Berlin park

The population of this genetically identical crayfish exploded within the pet trade, particularly among German aquarium hobbyists.

But with the species able to reproduce exponentially within a few months, people began releasing unwanted crayfish - also known as marmorkrebs - into ponds and lakes across Europe, creating the thriving wild populations seen today.

The freshwater creatures' ability to self-clone rapidly has led to them being compared with the fictional Tribble alien species from Star Trek, who are also able to multiply.

Introduced as a cheap source of protein in Madagascar, the all-female species is now threatening native ones, creating an ecological nightmare for authorities.

The European Union and two US states have already banned the marbled crayfish from being owned or traded, but populations in the wild continue to multiply.