The Chinese mitten crab is native to East Asia, where they are a delicacy. They have funny-looking, hairy claws which distinguish them from other crabs. Populations of this crab have invaded Europe and the United States and are causing concern due to potential ecological damage.
The Chinese mitten crab is most easily distinguished by its claws, which are white-tipped and covered in brown hair.
The shell, or carapace, of this crab is up to 4 inches wide and light brown to olive green in color. They have eight legs.
Other names for this crab are the Shanghai hairy crab and big binding crab.
- Kingdom: Animalia
- Phylum: Arthropoda
- Subphylum: Crustacean
- Class: Malacostraca
- Order: Decapoda
- Suborder: Pleocyemata
- Family: Varunidae
- Genus: Eriocheir
- Species: sinensis
The Chinese mitten crab is (not surprisingly) native to China, but expanded its range during the 1900s and is now considered an invasive species in many areas.
According to the Global Invasive Species Database, the Chinese mitten crab is one of the 100 “World’s Worst” invaders. If established in an area, the crab will compete with native species, foul fishing gear and water intakes, and can intensively burrow into shorelines and increase erosion problems.
In Europe, the crab was first detected in Germany in the early 1900s, and it has now established populations in European waterways between Scandinavia and Portugal.
The crab was found in San Francisco Bay in the 1990s and is believed to have been transported from Asia by ballast water.
The species has now been found in the eastern U.S., with several crabs caught in crab pots in Delaware Bay, the Chesapeake Bay and the Hudson River. This finding has caused biologists in other Eastern states such as Maine and New Hampshire to issue warnings urging fishermen and other water users to look out for the crab and report any sightings.
The Chinese mitten crab is an omnivore. Juveniles eat mainly vegetation, and adults eat small vertebrates such as worms and clams.
One reason this crab thrives is that it can live in both fresh and salt water. In late summer, Chinese mitten crabs move from fresh water to tidal estuaries to mate. The females overwinter in deeper salt water and then hatch their eggs in brackish water in the spring. With one female carrying between 250,000 and one million eggs, the species can reproduce rapidly. Once born, juvenile crabs migrate gradually upstream into fresh water, and can do so by walking over land.
While the crab is unpopular in the areas it has invaded, it is prized in Shanghai cuisine. The meat is believed by the Chinese to have a “cooling” effect on the body.
References and Further Information:
Gollasch, Stephan. 2006. “Eriocheir sinensis.” Global Invasive Species Database (Online). Accessed August 19, 2008.
Maine Department of Marine Resources. 2007. “Marine Biologists Track Invasive Crab” (Online), Maine Department of Marine Resources. Accessed August 19, 2008.
MIT Sea Grant. 2008. “Chinese Mitten Crab Alert” Massachusetts Institute of Technology (Online). Accessed August 19, 2008.