Petrolisthes eriomerus Stimpson, 1871
Common name(s): Flattop crab, Porcelain crab
|Petrolisthes eriomerus collected from Sares Head. Carapace width 1.3 cm|
|(Photo by: Dave Cowles June 26, 2005)|
How to Distinguish from Similar Species: Petrolisthes cinctipes has a shorter carpus and the margins are not parallel, plus the palp of its maxilliped is orange red. Pachycheles crabs such as Pachycheles rudis have much thicker chelae .
Geographical Range: Chicagof Island, Alaska to La Jolla, CA
Depth Range: Low intertidal to 86 m; primarily intertidal from central CA southward.
Habitat: Under rocks, on both exposed coasts and protected water. Also on kelp holdfasts and in mussel beds. Most common in areas with strong currents.
Biology/Natural History: Filter feeds (mostly
diatoms) using long setae on its second and third maxillipeds,
and also uses the setal tufts (picture) on
to sweep up material from rock surfaces. Crabs of this species
sometimes live together in groups of males, females, and young; with several
dominant males doing most of the breeding. Females often have two
broods per year. Has little resistance to desiccation. Petrolisthes
larvae have extremely long, distinctive rostrums.
As with most porcelain crabs, this species will very readily autotomize
if handled. Unlike P. cinctipes,
claw of this species can continue pinching.
|Main Page||Alphabetic Index||Systematic Index||Glossary|
Brusca and Brusca, 1978
Johnson and Snook, 1955
Morris et al., 1980
O'Clair and O'Clair, 1998
Russell, Robert M., Jr., 1961. Laboratory culture and developmental stages of Petrolisthes eriomerus Stimpson. Master's thesis, Walla Walla College. 35 pp.
This species is moderately common in the lower intertidal of Sares Head
Porcelain crabs, unlike true crabs, have uropods on their abdomens.
The undersized fifth leg is visible on porcelain crabs.
The tufts of setae present on the chelipeds can be seen when the animal is underwater. Notice also the blue on the chelipeds.
Photo by Dave Cowles, June 2005
|This individual, found at Swirl Rocks, clearly shows the blue coloration present on the maxillipeds and the chelae. Photos by Dave Cowles, July 2007|