Chesapeake Bay Introduced Species Database

Eriocheir sinensis

Common name(s):
Chinese Mitten Crab
The Chinese Mitten Crab is the only catadromous crab in the Atlantic. Catadromous means that they spend their adult lives in freshwater and their larval and juvenile lives in salt water; therefore you could find one of these fuzzy-clawed crabs in a freshwater stream or in your crab pot. Because mitten crabs invaded the Atlantic Coast only a few years ago, we don?t know very much about their status as an established population. But we are very concerned about them because in other areas where they have established populations they have caused both ecological and economic harm. We need your help to monitor and control the population while these crabs are still rare. If you find one, log in to Mitten Crab Watch ( and report your catch.
Image courtesy of CA Dept of Fish and Game.


Eriocheir sinensis


Eriocheir leptognathus Rathbun, Eriocheir rectus Stimpson

Potentially Misidentified As:

Eriocheir japonica; Eriocheir hepuensis

Common Names:

Chinese Mitten Crab


Eriocheir sinensis was described by Henri Milne Edwards in 1853 (Clark 2006).

Species Description- Crabs of the genus Eriocheir are easily recognized as adults and juveniles by the dense patches of setae (bristles or hairs) on their claws, which are responsible for the name "Mitten Crab". Both males and females have hairy claws, but the patches cover more of the claws in the males. The tips of the claws are white, and the claws are roughly equal in size. The carapace is slightly broader than it is long, and is roughly rectangular, with 4 teeth on its front margin. There is a frontal notch between the eyes. However, there is considerable variability in the frontal margin, which has led taxonomists to name spurious varieties (Guo et al. 1997; Rudnick et al. 2000). Legs are about twice as long as the carapace width, and in adults, the outer segments are lined with long hairs (Guo et al. 1997; Rudnick et al. 2000). In California, adults of E. sinensis reach 80 mm in carapace width (Rudnick et al. 2000). In crabs bigger than 10 mm, sexes can be distinguished by the shape of the abdomen, rounded in females, arrow and triangular in males (Rudnick et al. 2000).

Distinctive features of E. sinensis include a strongly domed carapace, with a strongly raised area over the stomach (progastric crest), which is lacking in E. japonica. The frontal teeth are sharper, with deeper divisions between them than those of E. japonica. and the anterior-lateral teeth are more sharply defined in the former species.

Family- Until recently, Eriocheir sinensis was placed in the family Grapsidiae. A molecular study of the family has found strong genetic divergences which support raising subfamilies to family status, within the superfamily Grapsoidea. The subfamily Varunidae now is treated as a full family and includes the genera Eriocheir, Hemigrapsus, and Cyclograpsus (Clark 2006, Integrated Taxonomic Information System 2006).

Synonymy, Potentially misidentified species- The taxonomy of the Mitten crabs of the genus Eriocheir is unresolved. Two species, E. leptognathus and E. formosa are definitely distinct, but may belong in a new genus, Neoeriocheir (Guo et al. 1997). Three other species, E. sinensis, E. japonica and E. hepuensis have been synonymized by some authors. However, E. sinensis and E. japonica have perceived morphological and behavioral differences, while E. hepuensis appears intermediate between the two forms (Guo et al. 1997; Jensen and Armstrong 2004). Eriocheir sinensis occurs in northern China and Korea, while E. japonica occurs in Japan, Taiwan, southeast Korea, and southern China, and E. hepuensis is confined to southern China (Guo et al. 1997). San Francisco Bay and European introduced populations have been identified as E. sinensis (Guo et al. 1997), but a single specimen collected in the Columbia River, in 1997, appears to be E. japonica (Jensen and Armstrong 2004). Tang et al. (2003) have analyzed nuclear DNA internal transcribed sequences (ITS) and divided the genus Eriocheir into 3 groups, Neoeriocheir leptognatha Panjin, E recta Zujiang (including E. formosa Hualien as a junior synonym), and E. japonica (including japonica, sinensis, and hepuensis as subspecies). Another molecular analysis, by Chu et al. (2003) argues for keeping keeping all the mitten crab species in a single genus.

This data was last modified on Wednesday, July 17th, 2013.
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