The best aspect of native tanks, is the surprise entrants that appear every now and then. I fed the tank with some scraps of sausage meat that my flatmate was throwing out and all creatures great and small emerge from their hiding places, including this bristly crab that I never knew I had!

With appendages covered with many setae I fist thought it was a brittle star arm poking out from between the rocks. One claw is bigger than the other, a key ID feature.

It is found primarily on the south and west coasts of mainland Britain and the east coast of Northern Ireland but there are records of it appearing in other sites around the UK (map). Found on a variety of substrate types from sand to rocky shore, and up to a depth of 80m and preferring areas with abundant algae and mussels.

They have a varied opportunistic diet, as with many crabs, feeding on carrion, small mussels or other animals. Very timid in the tank (hence not seeing it before now) and took a while for it to expose itself from its hiding place in order to retrieve food. An interesting little addition to the aquarium!

Phylogeny (source: Wikipedia)

Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Crustacea
Class:	Malacostraca
Order:	Decapoda
Infraorder:	Brachyura
Family:	Pilumnidae
Genus:	Pilumnus
Species:	P. hirtellus