Striped Shore Crab
Pachygrapsus crassipes
Summary 5
Pachygrapsus crassipes, known as the striped shore crab or lined shore crab, is a small crab found on rocky and hard-mud shores of the west coast of North to Central America and in the western Pacific in Korea and Japan. In North America, its range spans from Vancouver Island to Baja California, Mexico. The Asiatic population appears to not be invasive but endemic, resulting from a divergence estimated between 0.8 to 1.2 Mya. Typically, this crab...
Comprehensive description 6
The Lined Shore Crab (Pachygrapsus crassipes) is common from southern Oregon (U.S.A.) to Baja California (Mexico), where it inhabits the upper portions of rocky shores. Its coloration is variable, ranging from greenish to blackish to reddish with transverse (often green or red) stripes running across the carapace. The large pincers are sometimes red or may have red or purple lines. The body width of a large specimen is about 3 to 5 cm. These crabs live under rocks and in crevices. They feed extensively on algae (e.g., green algae such as Ulva, see Sousa 1979), tearing them up with their pincers. Some animals are eaten as well, including limpets and small crabs. Typically, it feeds by bringing its left and right pincers alternately to its mouth. (Kozloff 1993; Sheldon 1999)
Food habits 7
Pachygrapsus crassipes is omnivorous, which means it eats both plants and animals. The main diet consists of algae such as the green algae Ulva, and Enteromorpha, or it eats red algae such as Endocladia, Rhodoglossm, and Grateloupia. Brown seaweed such as Fucus. However, Pachygrapsus crassipes also eats diatoms, worms, muscles, Hemigrapsus oregonesis , small dead fish., limpets, snails as in Littorina and Tegula, hermit crabs, and isopods. Pachygrapsus crassipes can also become cannibalistic and eat each other (usually this occurs when they still have their soft-shell after molting).
The predators of Pachygrapsus crassipes are seagulls, rats, raccoons, and humans. Other predators that juvenile and larvae crabs need to watch out for are sea anemones and other fish (Barry & Ehret 1993; Quammen 1984).
Habitat 8
The Lined Shore Crab (Pachygrapsus crassipes) is found along rocky shores, in bays, in mussel beds, in estuaries and tidal creeks, and on pilings. Along tidal creeks, this crab may burrow into the soft, sandy banks. It appears at ease both on land and in the water. (Hui 1992; Sheldon 1999)
Pachygrapsus crassipes is found in the high intertidal zone of both bays and exposed coastal habitats of the North Pacific (Cassone and Boulding 2006 and references therein).
Physical description 9
Pachygrapsus crassipes can be red, purple, or green. The carapace (the back shell) is a boxy shape, it is broader than it is long. A distinctive feature P. crassipes is the series of horizontal lines across the carapace.
In this species, the males are larger than the females. The size difference is noticeable after the crab's carapace reaches the width of 22 mm. After they reach 22 mm sexual dimorphism is noticeable. The female's carapace becomes narrower and shorter than that of a male. The difference of the brachyuran on the abdomen is apparent. Other features that occur is the male chelipeds are 8 percent longer. And the propodite and dactylopodite in males are larger by 10%.
Pachygrapsus crassipes can reach the size of 47.8 mm for males and females the carapace can reach the size of 40.8 mm (Morris,et.al 1980; Mohler,et.al 1997; Hiatt 1984).
Sources and Credits
- (c) Ken-ichi Ueda, some rights reserved (CC BY-NC-SA), http://www.flickr.com/photos/18024068@N00/2555735350
- no rights reserved, http://www.flickr.com/photos/55368994@N06/12868844283/
- (c) 2007 California Academy of Sciences, some rights reserved (CC BY-NC-SA), http://calphotos.berkeley.edu/cgi/img_query?seq_num=70317&one=T
- (c) David Hofmann, some rights reserved (CC BY-NC-ND), http://www.flickr.com/photos/23326361@N04/4882731521
- Adapted by Marisa Rafter from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Pachygrapsus_crassipes
- (c) Shapiro, Leo, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/17763539
- (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/18663830
- (c) Shapiro, Leo, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/11290037
- (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/18663828
