St Piran’s hermit crab

Our second species in focus features probably the most popular new arrival to our shores in recent years. Well certainly in Cornwall anyway, where this charming little crab is named after the region's patron saint: St Piran.


Also known as the St Piran’s crab, Clibanarius erythropus is a small hermit crab (up to 30mm long) that inhabitant a range of empty gastropod shells, but mainly found in Dogwhelks (Nucella lapillus). Compared to the other hermit crabs found in the UK, its claws are equally sized and have black tips, which emerge after its legs. Look closely and you will see highlights of electric blue on its legs, claws and maniples. Its eyes are black with white dots. The St Piran’s crab is a warm water species and has only recently appeared in Cornwall and Devon.


The species name is Clibanarius erythropus Kingdom: Animalia – ‘animals’, Phylum: Arthropoda – ‘arthropods’, Subphylum: Crustacea – ‘crustaceans’, Order: Decapoda – ‘crayfish, crabs, lobsters, prawns, and shrimp’, Infraorder: – ‘false crabs’, Family:        Diogenidae – ‘hermit crabs’


Under rocks and boulders in the mid and low shore. Often seen climbing around the side of rocks and boulders and even sunbathing on flat surfaces out of the water to dry out its shell.


Primarily eats algae covering the side of rocks but can scavenge for detritus.

Rock Pool Project:

This species has been found at some of our events and is the 38th most recorded species of the 120 discovered by our project to date. It has been discovered at 4 of our survey sites, very frequently at Gylly beach in Falmouth. Being a member of the false crabs group it is included in our false crab biodiversity surveys and we have both presence and absence records for the species from various sites.

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Rock Pool Project discoveries for this species: