(Dana, 1851) 
Pagurus hirsutiusculus is a species of hermit crab, commonly called the hairy hermit crab. It lives from the Bering Strait south to California and Japan, from the intertidal zone to a depth of 110 m (360 ft).
Adults range in color from olive green to brown to black. Distinguishing characteristics of this hermit crab are white and often also blue bands on the walking legs. The antennae are grayish-brown with distinct white bands. This hermit crab is also easily identified by the remarkable amount of hair covering its body. The carapace of an adult P. hirsutiusculus may measure up to 19 mm (0.75 in) in length, and the animal's body may grow to 70 mm (2.8 in) in northern populations. Populations further south than Puget Sound are smaller and less hairy, and have been recognized as a separate subspecies, P. h. venturensis.
Range and habitat
P. hirsutiusculus is found from the Pribilof Islands, Alaska to southern California, and from the Bering Strait south to Japan. It lives at depths ranging from the middle intertidal zone to 110 m (360 ft), generally lower than Pagurus samuelis. It is commonly found in tide pools with sand or rock, and under rocks, logs, and seaweed, and is the common hermit crab of San Francisco Bay.
As is common with hermit crabs, P. hirsutiusculus carries an abandoned gastropod shell to protect itself. Individuals from calmer waters will readily leave their shell when confronted with a predator, a trait which the authors of Between Pacific Tides attributed to the lack of surf. the preferred shells are those of Nassa, Olivella biplicata, Nucella emarginata, Tectarius striatus, Epitonium tinctum, Alia carinata, Homalopoma luridum, Ilyanassa obsoleta, Urosalpinx cinerea, and Busycotypus canaliculatus. In the San Juan Archipelago, Pagurus hirsutiusculus has been found to carry the parasitic isopod Pseudione giardi.
P. hirsutiusculus mainly feeds on detritus, but is an opportunistic feeder and also feeds on seaweeds. The right chela of P. hirsutiusculus is significantly larger than the left and is used primarily for defense. The smaller left chela is used for fine motor work such as eating and selecting gastropod shells. The setae on the minor chela are sensitive to calcium, and help the hermit to judge whether the gastropod shell will be adequate to suit its needs.
- "Pagurus hirsutiusculus (Dana, 1851)". Integrated Taxonomic Information System. Retrieved June 20, 2011.
- Patsy McLaughlin (2010). P. McLaughlin, ed. "Pagurus hirsutiusculus (Dana, 1851)". World Paguroidea database. World Register of Marine Species. Retrieved June 25, 2011.
- Edward Flanders Ricketts, Jack Calvin, Joel Walker Hedgpeth (1992). "Rocky shores of bays and estuaries". Between Pacific Tides (5th ed.). Stanford University Press. pp. 269–316. ISBN 978-0-8047-2068-7.
- Robert H. Morris, Robert Hugh Morris, Donald Putnam Abbott, Eugene Clinton Haderlie (1980). "Pagurus hirsutiusculus (Dana, 1851)". Intertidal Invertebrates of California. Stanford University Press. pp. 585–586. ISBN 978-0-8047-1045-9.
- Karen A. Mesce (1993). "Morphological and physiological identification of chelar sensory structures in the hermit crab Pagurus hirsutiusculus (Decapoda)". Journal of Crustacean Biology 13 (1): 95–110. JSTOR 1549125.
- J. Duane Sept (1999). The Beachcomber's Guide to Seashore Life in the Pacific Northwest. Madeira Park, British Columbia: Harbour Publishing. p. 117. ISBN 978-1-55017-204-1.
- Gregory C. Jensen (1995). Pacific Coast Crabs and Shrimps. Montgomery, California: Sea Challengers. p. 66. ISBN 978-0-930118-20-4.
- Eugene N. Kozloff (1983). Seashore Life of the Northern Pacific Coast: an Illustrated Guide to Northern California, Oregon, Washington, and British Columbia. University of Washington Press. p. 132. ISBN 978-0-295-96084-5.
- Andrew Lamb & Bernard P. Hanby (2005). Marine Life of the Pacific Northwest: a Photographic Encyclopedia of Invertebrates, Seaweeds and Selected Fishes. Madeira Park, British Columbia: Harbour Publishing. p. 314. ISBN 978-1-55017-361-1.