Petrolisthes cinctipes, commonly known as the flat porcelain crab, is an abundant species[2] of marine porcelain crab found in the upper and middle intertidal, primarily in mussel beds, along the eastern Pacific Ocean, from British Columbia to Mexico.[3] This species was first described by John Witt Randall in 1840.[4]
P. cinctipes has a flat carapace up to 24 mm in diameter.[2][5] It is generally a dark blue-brown color, and more starkly blue around the time of molting.[2] The species name cinctipes is derived from the Latin for "banded legs," since the legs of this species are blue banded with white.[6] Unlike other sympatric species of Petrolisthes, this species has dark red antennal flagellae, and a distinct lobe on the inner margin of its carpus, which has non-parallel margins.[7]
Biology
P. cinctipes does not use its chelae (claws) for feeding.[8] Like other porcelain crabs, P. cinctipes is a suspension-feeding crab that uses its maxillipeds (mouthparts) to sweep phytoplankton and other detritus from the water.[9] It can voluntarily detach its claw through a reflex called autotomy, which it deploys in approximately 40% of predator attacks or more,[8] especially among smaller female porcelain crabs.[10] The claw stops pinching once it detaches, which is not the case for other species in the genus, like P. eriomerus.[7] After autonomy, a membrane is sealed over the stump, and within a few weeks a small limb bud will form at the amputation site.[9] After several molting cycles, the limb bud will retain its full size.
P. cinctipes generally reproduce all year round. Eggs hatch into zoea, or early-stage planktonic larvae with long spines,[5] which the larvae use both for lateral swimming[11] and to discourage predators.[2] Zoeal larvae molt once before entering a post-larval stage as planktonic, filter feeding megalopae with fully developed appendages.[9] After molting again, individuals generally lose the ability to swim as they reach the juvenile stage.[2] However, adults, can swim with their ventral side up if they are forced to.[7]
Research
P. cinctipes has been used as a model organism in studies of intertidal ecology,[12] competition,[13] and adaptation to stressors like acidification[14] and temperature fluctuation.[15] Its accessible habitat and abundance make it a common subject in marine biology teaching laboratories.
References
↑ NatureServe (9 May 2016). "Petrolisthes cinctipes". NatureServe Network Biodiversity Location Data accessed through NatureServe Explorer. NatureServe. Retrieved 29 September 2025.
1 2 3 4 5 Hiebert, Terra Celeste; Butler, Barbara; Shanks, Alan L (2016). Oregon Estuarine Invertebrates: Rudys' Illustrated Guide to Common Species, 3rd Edition. University of Oregon Libraries.
↑ Russo, Ron; Olhausen, Pam (1981). Pacific Intertidal Life: A guide to organisms of rocky reefs and tide pools of the Pacific Coast. AdventureKEEN. p.44. ISBN978-0-912550-32-9.
↑ Schmitt, Waldo Lasalle (1921). The Marine Decapod Crustacea of California: With Special Reference to the Decapod Crustacea Collected by the United States Bureau of Fisheries Steamer" Albatross" in Connection with the Biological Survey of San Francisco Bay During the Years 1912-1913. University of California Publications in Zoology. pp.1--359.
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