Clibanarius erythropus is a species of hermit crab that lives in rockpools and sublittoral waters.[1] It is found in the Mediterranean Sea, Black Sea and eastern Atlantic Ocean from the Azores to Brittany, the Channel Islands and as far north as the south Cornwall coast.[1] [2] [3] Individuals may grow up to a carapace length of 15mm.[1]
A variety of different gastropod shells are used by C. erythropus, the most frequent being Littorina striata, Mitra, Nassarius incrassatus and Stramonita haemastoma, which collectively account for 85% of all the individuals studied in the Azores;[4] in the Mediterranean, shells of Cerithium, Alvania montagui and Pisania maculosa are most used by C. erythropus.[5]
Like other hermit crabs, C. erythropus feeds on "organic debris, decayed and fresh macro-algae with associated fauna and epiphytic algal flora, small invertebrates, and macroscopic pieces of dead and live animal tissues".[2] It has been shown that C. erythropus individuals select substrates where they can cover large distances, and that globose shells allow them greater mobility than elongate ones.[2]
In 2016 the BBC Springwatch programme highlighted C. erythropus and ran a competition to provide a vernacular name. The winning name was St Piran's crab, a process supported by National Trust West Cornwall and the Cornwall Wildlife Trust. Saint Piran is generally regarded as the patron saint of Cornwall, and was a hermit who survived being thrown into the sea.[6] [3]