We found a couple of these crabs amongst the Pacific Oyster beds at Colne Point in Essex, during a shoresearch survey. We have never seen anything like these before in over forty years of shore searching. The only thing that comes anything near is the Asian shore crab, Hemigrapsus sanguineus, which I understand has been reported from the Channel Islands. Can anyone identify it? My fingers should give an idea of the size. The right cheliped was missing, but the left one gave me a nip!
Maya Plass on the BBC Autumnwatch blog suggests that this may be a young Marbled Rock Crab Pachygrapsus marmoratus. This is a Mediterranean and Southern European species that seems to be spreading north. It has been recorded on the south coast of England. The adult has a nice marbled pattern on the carapace, which this one lacks.
That is one I havn't come across yet. I will look out for this one now too.
I keep wondering if there is a group of crab enthusiasts - a bit like the twitchers and birders of the bird watching world - who might flag up new species to go and search for. Is there such a group of enthusiasts? Is there anyone else interested in going on a crab hunt or two? My interest would not necessarily be limited to The UK, or to Europe. I think there are 19 species of land crab on Christmas Island for example - now that would be a trip worth doing!