Pagurus

Lore & Background

Pagurus is a genus of hermit crabs in the family Paguridae. Like other hermit crabs, their abdomen is not calcified and they use gastropod shells as protection. These marine decapod crustaceans are omnivorous, but mostly prey on small animals and scavenge carrion. Trigonocheirus and Pagurixus used to be considered subgenera of Pagurus, but the former is nowadays included in Orthopagurus, while the latter has been separated as a distinct genus. Some 170 species are presently placed in Pagurus; many others have been placed here at one time but are now assigned to other genera of Paguroidea. The following species are among those currently recognized: Pagurus anachoretus, Pagurus bernhardus, the long-armed hermit crab Pagurus longicarpus, and the hairy hermit crab Pagurus hirsutiusculus, which has a soft-shelled and curved abdomen. Several names have been published as nomina nuda—never validly described as new species, but only mentioned under these names: Pagurus bunomanus, Pagurus crenatus, Pagurus cuanensis, Pagurus cultratus, Pagurus hirtimanus, Pagurus hyndmani, Pagurus laevis, and Pagurus ulidiae.

Reader's Guide

Pagurus is a large and historically significant genus of hermit crabs, with some 170 species currently recognized. Its members are notable for their uncalcified abdomen and reliance on gastropod shells for protection, a defining trait of hermit crabs. The genus has undergone taxonomic revision: the former subgenera Trigonocheirus and Pagurixus have been reassigned, with Trigonocheirus now placed in Orthopagurus and Pagurixus elevated to a distinct genus. Many species once classified under Pagurus have been moved to other genera within Paguroidea, reflecting ongoing refinement of decapod systematics. The genus includes well-known species such as Pagurus bernhardus and the hairy hermit crab Pagurus hirsutiusculus, the latter illustrating the soft, curved abdomen typical of the group. Several nomina nuda—names like Pagurus bunomanus and Pagurus cuanensis—have been published without valid descriptions, indicating gaps in formal taxonomy. Pagurus remains a central genus for understanding hermit crab biology, shell use, and scavenging ecology in marine environments.

Did You Know?

• Pagurus hermit crabs have an uncalcified abdomen and use gastropod shells for protection.
• Trigonocheirus and Pagurixus were once considered subgenera of Pagurus but have since been reclassified.
• Some 170 species are currently placed in Pagurus.
• Several names in Pagurus, such as Pagurus bunomanus, are nomina nuda—never validly described.