An exotic crab has been found in British waters for the first time after travelling 4,000 miles across the Atlantic on a piece of polystyrene.
The short-spined hairy crab was found on Chesil Beach, near Weymouth, Dorset by naturalist Steve Trewhella.
The animal is usually found in warm waters such as the Caribbean and the Gulf of Mexico but was washed up in the UK on a polystyrene shellfish buoy from Florida Keys.
The tiny crab was barely alive when he was found while Mr Trewhella was picking through marine litter after a storm.
Mr Trewhella said: ‘It was covered in goose barnacles which don’t occur in our waters and was a sure sign that the object had been out in the open ocean for some time.
‘I then noticed a small crab living in a hollow it had made in the polystyrene, it was a hairy crab species.
‘We have hairy crabs in the UK and at first glance it looked very much like ours. However, my gut feeling was this crab had travelled on this buoy for some time.’
The crab subsequently died, so Mr Trewhella stored him in a freezer at home and contacted Dr Paul Clark, a researcher in the life sciences department at the Natural History Museum.
Studies by the Natural History Museum have confirmed that the Pilumnus dasypodus, a Caribbean species, has previously never been seen in British waters
The short-spined hairy crab was found on Chesil Beach, near Weymouth, Dorset by naturalist Steve Trewhella
The tiny crab was barely alive when he was found by Mr Trewhella, who was picking through marine litter after a storm
Dr Clark said: ‘When Steve sent the crab to me it was a bit of a puzzle. We had to look at the morphology, the structure of the crab.
‘It came to me frozen; we then put it in alcohol before studying it.
‘We noticed that the frontal margins are similar but they had grown slightly wider on the specimen on the buoy. When you look closely you can see the subtle difference.
‘Because of the buoy we know that it came from the Florida Keys but we have been unable to contact the fisherman.’
Studies by the Natural History Museum have confirmed that the Pilumnus dasypodus, a Caribbean species, has previously never been seen in British waters.
Dr Clark added: ‘Invasive species like these are a real issue because they take away the biodiversity of our area.
‘If this keeps happening we could get a new invasive species coming from across the Atlantic.
‘If this had been a female carrying eggs which then hatched it could create a number of juveniles which might establish a population.
‘We just have no idea what effect the crab would have in Europe if it established a population.’
Experts said global warming could lead to more of the exotic crabs crossing the Atlantic and if a female survived and laid eggs invasive species would compete with native marine life.
A scientific paper, entitled ‘An American in Chesil Cove’, has now been published, detailing the scientific work.
There are 65 crab species in the UK, with the shore crab being the most common.
