Geographical Range: Charlston, Oregon to Isla de Santa Margarita, Baja California, + Gulf of California, Japan, Korea (it may have been introduced to Asia)
Depth Range: High and mid intertidal
Habitat: Crevices, under rocks, in tidepools and mussel beds. Sometimes in clay burrows, especially in San Francisco Bay.
Biology/Natural History: This crab can be very abundant in its range. It is the most semi-terrestrial of the shore crabs, living highest in the intertidal. Forages in and out of the water, active during the day. They spend at least half their time out of water but return periodically to pools to moisten their gills. They are osmoregulators, and can withstand hypo- and hyperosmotic conditions. It feeds on films of algae and diatoms, which it scrapes off the rocks with the tips of its chelae. May also eat small green algae Ulva and Enteromorpha, brown algae Fucus, and red Endocladia, Rhotoglossum, and Grateloupia. Occasionally eats dead animals or small intertidal invertebrates, and has especially been noted eating limpets. Predators include gulls, raccoons, anemones, and fish. Ovigerous females are found from March to September in central California; peak reproduction is in June and July.
In central Japan this species can be parasitized by any of
sacculinid barnacles, Sacculina confragosa, S.
or S. yatsui (Tsuchida et al., 2006).
Kozloff 1987, 1996
Smith and Carlton, 1975
López-Duarte, Paola C., Henry S. Carson, Geoffrey S. Cook, F. Joel Fodrie, Bonnie J. Becker, Claudio DiBacco, and Lisa A. Levin, 2012. What controls connectivity? An empirical, multi-species approach. Integrative and Comparative Biology 52:4 pp. 511-524
Sjoboen, A. D., Dunbar, S.G., and Boskovic, D. 2010. Temporal fluctuations of fatty acids in Pachygrapsus crassipes from Southern California. Journal of Crustacean Biology. 30(2): 257 – 265
Tsuchida, Kohei, Jorgen Lutzen, and Mutsumi Nishida, 2006. Sympatric three-species infection by Sacculina parasites (Cirripedia: Rhizocephala: Sacculinidae) of an intertidal grapsoid crab. J. Crustacean Biology 26:4 474-479
General Notes and Observations: Locations, abundances, unusual behaviors:
Note: This grapsid crab likes to pinch, and can readily draw blood! It is more likely to do so than are the Hemigrapsus species.
Authors and Editors of Page:
Dave Cowles (2005): Created original page