Chinese Mitten Crab
(Eriocheir sinensis)

Description: The hairy "mittens" on the claws of this crab set it apart from any local species. The claws are white-tipped, while the rest of the body varies from an olive green to a dark brown color. The carapace is round, has four pronounced lateral spines on either side of the eye stalks, a distinctive U-shaped notch between the eyes, and can grow up to 80 mm across.

Habitat: The mitten crab is an excellent digger and burrows into the soft mud along the banks of waterways. Tolerating a wide range of salinity levels, it occupies rivers, estuaries, lagoons, and nearshore waters. Adult crabs reproduce in salt water, and offspring migrate to freshwater.

Origin: China and Korea.

Invaded Areas: San Francisco Bay, Northern Europe.

Concerns: Considered a delicacy by Asian diners, this crab has the ability to cause ecological and economic damage, as well to pose a health risk to people who eat them. It is therefore illegal to import, transport, or possess live mitten crabs in the United States. In areas of high infestation, mitten crabs can increase erosion when burrow-ridden banks cave in. They may affect native invertebrates through predation or compete with benthic predators. Their impact on commercial fisheries is also of economic concern. For example, unintentionally caught mitten crabs cause considerable damage to fishing gear by cutting nets, and can feed on netted catch. In its native range, the Chinese mitten crab is a secondary intermediate host for the Oriental lung fluke.