A visitor to a nature reserve near Huntingdon had a shock when a crab the size of a small dinner plate was on the footpath.  

Simon Passey was walking back to the car park at the RSPB Fen Drayton Nature Reserve on Sunday (September 26) when he came across the creature. 

The charity has since confirmed it is a Chinese mitten crab, which is considered to be one of the world’s 100 worst invasive species.  

Simon, a wildlife enthusiast who uploads his wildlife photography to Instagram, said: “It certainly took us by surprise.  

“My wife said: ‘Watch out, you’re going to tread on something.’  

“I looked down and it was a crab.  

“It was alive and had quite large pincers – I've never seen anything like that at Fen Drayton before. 

“I took photos – but I didn’t want to touch it.” 

The RSPB has not yet confirmed whether this is the first crab to be spotted at Fen Drayton.  

But Simon reported the sighting to the Mitten Crab Watch, which is run by The Marine Biological Association Recording Scheme.   

Describing the crabs, its website says: “They can cause damage to fishing gear and river banks, block intake screens, modify natural habitats and compete with native species.  

“It is this economic and ecological damage that makes this crab such an unwelcome arrival. 

“The full extent of these exotic pests in English and Welsh waters is currently unclear and a consortium of research institutes is requesting mitten crab sightings... to clarify the distribution of this species.” 

Mitten crabs can be a grey-green to dark brown in colour, have long walking legs, a squarish body up to 86mm across.  

Adults tend to have dense brown 'fur' on the white-tipped claws. Fur can be lacking in juvenile crabs. 

Mitten crab sightings can be reported at www.mittencrabs.org.uk.