Maroon Hermit Crab

Pagurus. hemphilli is a rich maroon color with small blue dots, yellow-tipped dactyls, gold-ringed corneae, and red to orange-red antennae that lack spots or rings. Juveniles sometimes have white bands on their ambulatory legs. The chelipeds ("claws") are dramatically different in size, with the major cheliped being much larger than the minor cheliped. It is almost totally hairless over its entire body and has a smooth, shiny shield. It has a distinct rostrum that is produced well beyond the carapace lateral frontal lobes. The chela palms are rough with visible bumps. The uropods are asymmetrical, and the carapace can measure up to 15 mm (0.6 in).

Pagurus hemphilli ranges along the North American coast from Alaska to the Central Coast of California. It is more common towards the southernmost extent of its range in Central California.

Most commonly, P. hemphilli dwells in the shells of Tegula species, such as Tegula brunnea, Lithopoma species, and Astraea species. To acquire a better shell, P. hemphilli engages in shell fights, with the loser conceding their shell. These shell fights may be intraspecific or with other Pagurus species. In these fights, the larger hermit crab has the advantage.

The shells that this species inhabits are often heavily encrusted with coralline algae and with hitchhikers like the slipper snail Crepidula adunca and the limpet Acmaea mitra. A species of Amphipod in the genus Liljeborgia has been observed residing with this species of hermit crab inside the shell; this commensal occupant remains undescribed.