Very special thanks for the first photo of Petrolisthes cinctipes to Gary McDonald, Gary has taken this photo at Carmel-by-the-Sea, California State Park, USA.
Carapax lenght of this photographed flat porcelain crab: 1,5 cm.
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.
Porcellana rupicola Stimpson, 1857
Classification: Biota > Animalia (Kingdom) > Arthropoda (Phylum) > Crustacea (Subphylum) > Multicrustacea (Superclass) > Malacostraca (Class) > Eumalacostraca (Subclass) > Eucarida (Superorder) > Decapoda (Order) > Pleocyemata (Suborder) > Anomura (Infraorder) > Galatheoidea (Superfamily) > Porcellanidae (Family) > Petrolisthes (Genus) > Petrolisthes cinctipes (Species)