Petrolisthes cinctipes (Randall, 1839)

Common name(s): Flat porcelain crab, Smooth porcelain crab
Synonyms:  Petrolisthes rupicolus, Porcellana cinctipes, Porcellana rupicola
Phylum Arthropoda
 Subphylum Crustacea
  Class Malacostraca
   Subclass Eumalacostraca
    Superorder Eucarida
     Order Decapoda
      Suborder Pleocyemata
       Infraorder Anomura
        Superfamily Galatheoidea
         Family Porcellanidae
Petrolisthes cinctipes from San Simeon, CA.  Carapace width approx. 1.5 cm
(Photo by: Dave Cowles, May 2001)
Description:  Porcelain crabs are Anomuran crabs, as can be seen by the antennae being lateral to the eyes, the reduced last leg, and the fact that the abdomen is not held tightly against the underside of the thorax.  The abdomen of Petrolisthes has uropods. The cheliped of  Petrolisthes cinctipes has a carpus about 1.5-2x as long as wide, its anterior and posterior margins are not parallel (see photo above), and it has a distinct lobe on the inner margin.  The distal segments of the maxillipeds are reddish (photo).  The walking legs are banded.  Overall color reddish brown; occasionally blue.  Carapace length up to 2.4 cm, width to 1.4 cm.  Chelae are usually nearly equal in size and strongly flattened.  Antennal flagellum is reddish (photo).

How to Distinguish from Similar Species:Petrolisthes eriomerus has a cheliped with a longer carpus with parallel margins, its antennal flagellae are greenish, and it has blue on its mouthparts and on the cheliped.

Geographical Range:  Queen Charlotte Islands, Canada to Point Conception, CA + northern Channel Islands in CA.  Most common in southern part of range.

Depth Range:  Upper and middle intertidal

Habitat:  Under stones and in mussel beds., especially on the outer coast.

Biology/Natural History:  A very common inhabitant of mussel beds in central and northern California.  Feeds on plankton and suspended detritus by using the feathery hairs on its maxillipeds, which it waves in the water.  Occasionally eats algae or dead animal tissue.  Reproduces all year in California, March to July in Puget Sound.  Eggs are bright red or maroon when laid, fade to brownish red.  As with all porcelain crabs, this species will readily drop (autotomize) its claws if grasped by them (probably the source of the name--they break easily like fine china).  Unlike P. eriomerus, the claw of this crab stops pinching when dropped.  The zoea larvae of porcelain crabs have extremely long spines, especially the rostral spine.  This species can often be found in the same areas as P. eriomerus, but this species avoids hiding under rocks that have sand or sediments around them so they are usually higher in the intertidal.  They don't generally swim, but if forced to do so they often swim with their ventral side up, flapping their abdomen with their uropods extended for propulsion.

Individuals are often found with puncture wounds on their claws (Rypien et al., 2007).  This seems to be due to interspecific competition in the form of "shoving matches".  The incidence of injuries is similar for males and females, suggesting the competition may be for space rather than for mates.  Injuries are most common on intermediate (not the largest) individuals and in more crowded, wave-exposed sites.


 
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References:

Dichotomous Keys:
  Flora and Fairbanks, 1966
  Hart, 1982
  Kozloff 1987, 1996
  Smith and Carlton, 1975
  Wicksten, 2009
 

General References:
  Jensen, 1995
  Johnson and Snook, 1955
  Kozloff, 1993
  McConnaughey and McConnaughey, 1985
  Morris et al., 1980
  O'Clair and O'Clair, 1998
  Ricketts et al., 1985
  Sept, 1999

Scientific Articles:

Stillman, Jonathon H., John K. Colbourne, Carol E. Lee, Nipam H. Patel, Michelle R. Phillips, David W. Towle, Brian D. Eads, Greg W. Gelembuik, Raymond P. Henry, Eric A. Johnson, Michael E. Pfrender, and Nora B. Terwilliger, 2008.  Advances in crustacean genomics.  Integrative and Comparative Biology 48:6 pp 852-868

Stillman, Jonathon H., Kristen S. Teranishi, Abderrhamane Tagmount, Erika A. Lindquist, and Peter B. Brokstein, 2006.  Construction and characterization of EST libraries from the procelain crab, Petrolisthes cinctipes.  Integrative and comparative biology 46:6 919-930 : Characterizing genes which are transcribed in this species under different temperature conditions.

Rypien, Krystal L. and A. Richard Palmer, 2007.  The effects of sex, size and habitat on the incidence of puncture wounds in the claws of the porcelain crab Petrolisthes cinctipes (ANOMURA: PORCELLANIDAE).  J. Crustacean Biology 27:1 59-64
 

Web sites:
 


General Notes and Observations:  Locations, abundances, unusual behaviors:



View of the mouthparts.  Note that there is no blue border on the mouth parts--instead they have a reddish border.



Front view.  Note that the antennal flagellae are red.
 


Authors and Editors of Page:
Dave Cowles (2006):  Created original page