Of all the things to storm a cemetery, I doubt many of us would put escaped mutant crayfish high on our list and yet this is the exact scene unfolding in a graveyard in Belgium (<enter 2020 joke here>). The freshwater invaders are similar to the Florida slough crayfish but were bred by German pet traders in the 90s to become parthenogenetic, meaning they can asexually reproduce to create clones of themselves. The mutation means that if even a single individual makes it into the wild, they can quickly explode in numbers and take over rivers, streams or, as it seems, cemeteries.

Known by the species name Procambarus virginalis, the global population of these voracious reproducers were recognized as descendants of a single female back in 2018, as researchers discovered they were all female and didn’t need males as they could clone themselves. The European Union put in sanctions to ban the ownership and release of P. virginalis in 2014 but tracking down guilty parties is easier said than done when all members of the species are genetically identical.

As such, exactly where the cemetery-dwelling crayfish came from isn’t clear, but it’s suspected they were released into the wild from someone’s private aquarium. Since their arrival, this hoard of females has firmly taken up residence in the freshwater pools and streams of the Schoonselhof Cemetery in Antwerp. The crayfish are about 10 centimeters (4 inches) in length and can dig a meter (3.3 feet) into the ground, causing significant disruption to the integrity of the landscape and shaking up the ecosystem as their numbers surge. In true zombie apocalypse style, they feed at night eating whatever they can as they traverse the land and water by moonlight.

The mutant crayfish don’t occur in nature, a status that would normally give wildlife authorities the position to eradicate them from the wild, but the solution is not so simple when dealing with an ever-increasing population of self-replicating crustaceans. "It's impossible to round up all of them,” said Kevin Scheers, from the Flemish Institute for Nature and Woodland Research, to the Brussel Times. “It's like trying to empty the ocean with a thimble."

The plan of action against the crayfish invasion is undecided at the time of writing. Similar infestations in Spain have historically been dealt with using poisons, but such chemical-based treatments aren’t permitted in Belgium. For now, the female, mutant, escapee crayfish (said to the tune of Teenage Mutant Ninja Turtles) are free to reign supreme.

Invasive species in a calcium-carbonate-shell, crayfish power!