A warning has been issued by environmental groups after an invasive crab species was spotted in Norfolk.
Reports of Chinese Mitten Crabs being seen in the Buckenham and Oby areas have spurred ecological organisations to appeal to the public to be on the watch for the harmful interlopers.
Liam Smith, nature recovery officer at the Norfolk Non-Native Species Initiative, said: “The news about Mitten Crabs at Buckenham and Oby is worrying.
The crabs can cause severe ecological damage and should be reported wherever seen. (Image: Christian Fischer)
“The species is already known around the north-west coast of Norfolk and down in Suffolk but currently they haven’t properly colonised the Broads system.
“If that were to happen it could be really bad news.”
According to the initiative, Chinese Mitten Crabs are native to East Asia but have been introduced across Europe and first appeared in the UK in 1935 in the Thames Estuary.
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The crabs breed in salt water but migrate into freshwater areas in the spring where they spend three to five years growing to adulthood.
Fully adult crabs will march over dams, weirs and any other obstacles in the autumn to find their way back to the sea to spawn and die.
Chinese Mitten Crabs can grow to have a shell width of around three inches across and have legs almost double this length.
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Their most distinctive features are the dark, furry-looking growths on each of their front claws which is where they get their name.
The Norfolk Non-Native Species Initiative is trying to track their spread across Norfolk and would like the public help if they think they may have seen any.
If you have seen or caught a crab in freshwater, take a photograph of it and send it to NNNSI@norfolk.gov.uk with the location.