Aquarium Accident May have Given Crayfish the DNA to Take Over the World

It sounds like a bad monster movie plot: A 10-legged mutant creature that reproduces asexually, escapes from confinement in Germany, and quietly begins a global invasion. Within 2 decades, clones of the voracious animal spread through Europe and Africa, bringing devastation to ecosystems and threatening native species.

That appears to be the strange-but-true story of the marbled crayfish, an invasive freshwater species suspected to have been created through a reproductive accident in an aquarium around 1995. A new analysis of the crustacean’s genome supports this unlikely origin and may help explain how the animal has subsequently spread and adapted to so many new environments.  Click on the following two links below to access the full story.

The crayfish’s unusual evolution could also suggest a strategy to tackle a more infamous clonal monster: cancer. “In many ways, the invasive expansion of [the marbled crayfish] is analogous to a cancerous lineage spreading asexually at the expense of its host,” says Jean-François Flot, an evolutionary genomicist at the Free University of Brussels who was not involved with the work.  The marbled crayfish is the only crustacean that reproduces asexually, with the all-female species making clones of itself from eggs unfertilized by sperm. It has been thought to have arisen when two slough crayfish, imported from Florida for the aquarium trade in Germany, mated.

Stopping their spread in Madagascar will be “almost impossible”, says Lyko. Collaborators there have begun campaigns urging people not to transport them or release them into rice fields. The message is a hard sell in a country where poverty levels are high and marbled crayfish are a cheap and popular source of protein. 

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