Hundreds of self-cloning mutant crayfish are wreaking havoc in a historic cemetery in Belgium.
Marbled crayfish reproduce asexually through parthenogenesis – embryos develop without the need for sperm – birthing offspring that are genetically identical females.
It’s believed they evolved from a mutation in a slough crayfish about 25 years ago.
Because of the way they reproduce, large populations can grow rapidly and become a nuisance.
Since being discovered in 1995, the crayfish has spread from Germany across Europe and into Africa in huge numbers.
Now the four-inch crustaceans are clogging up pools and streams in Schoonselhof Cemetery in Antwerp.
Experts warn the crayfish will eat anything they can get their claws on, which will be devastating to the local biodiversity.
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Marbled crayfish reproduce asexually through parthenogenesis – meaning embryos develop without the need for sperm and all offspring are genetically identical females. Their populations can grow rapidly and quickly threaten local biodiversity
Known for its voracious appetite, the marbled crayfish, or Procambarus virginalis, can travel across land and water and dig up to four feet deep.
‘It’s impossible to round up all of them,’ Kevin Scheers of the Flemish Institute for Nature and Woodland Research told The Brussels Times. ‘It’s like trying to empty the ocean with a thimble.’
The crustaceans, which are believed to have been dumped by German pet traders in the 1990s, are also known by their German name, Marmorkrebs.
Researchers believe these mutant creatures evolved randomly in the mid-1990s, after a German aquarium hobbyist bought a crustacean he was told was a ‘Texas crayfish.’
Hundreds of marbled crayfish are clogging up ponds and streams in Schoonselhof Cemetery in Hoboken, a suburb of Antwerp.
But the enthusiast was surprised when his pet produced hundreds of eggs at a time with no male in sight.
He gave away the offspring, which ended up being sold in pet shops in Germany.
‘Often people get tired of their animals or the marbled crayfish population is getting too large at home,’ Scheers surmised.
They are banned in the European Union and in parts of the US and Canada.
Researchers believe these mutant crayfish evolved accidentally in the mid-1990s. A German aquarium hobbyist who bought what he was told was a ‘Texas crayfish’ found it had produced hundreds of eggs with no male in sight. They were then sold by pet traders and found their way into the wild by owners who no longer wanted to care for a growing number of crustaceans
In 2018, scientists decoded the crayfish’s genome and confirmed the species was descended from a single female.
Located in the Antwerp suburb of Hoboken, Schoonselhof Cemetery is home to the graves of celebrated Belgian writers, artists and Olympians.
Schoonselhof Cemetery is home to the graves of celebrated Belgian writers, artists, Olympians and more than 1,500 British commonwealth soldiers who died in World War II
More than 1,500 British commonwealth soldiers who died in World War II are buried there, too, including MP John Rathbone.
Left unchecked, the crayfish will eat anything they can get their claws on, devastating local biodiversity and crowding out other crayfish species.
Marbled crayfish have been located elsewhere in Antwerp and in Leuven, about 40 miles away.
They’ve also been spotted in the wild across Europe – including Germany, France, the Netherlands, Hungary, Denmark – as well as in Israel and Japan.
The population in Madagascar has exploded over the past decade, with some locals viewing it as a cheap plentiful source of protein.
Though they are a pest, the crayfish could help scientists understand how cancer tumors develop resistance to certain drugs.
Both the crayfish and tumors have ‘epigenetic mechanisms’ that allow them to adapt to different environments by switching certain genes on or off.
HOW DOES CLONING HAPPEN IN NATURE?
Asexual reproduction – when an organism reproduces without fertilisation – only requires one parent, unlike sexual reproduction, which needs two parents.
Since there is only one parent, sec cells (sperm and eggs) don’t fuse and no genetic mixing takes place.
Because of this, the offspring of asexual reproducing organisms are genetically identical to the parent and to each other – they are clones.
For instance, female marble crayfish can induce her own eggs to start dividing into embryo .
Normal sex cells contain a single copy of each chromosome. But the mutant crayfish sex cell has two.
The two sex cells fuse and produce a female crayfish embryo with three copies of each chromosome instead of the normal two.
Some other examples of organisms that can clone themselves include:
- Hammerhead sharks
- Marmokrebs (marbled crayfish)
- Desert grassland whiptail lizards
- Gall wasps
- Komodo dragons