Chinese Mitten Crab

A study on mating communication shows that mate recognition occurs only after physical contact. The study indicates that once physical contact is established, a contact pheromone is involved.

Communication Channels: tactile ; chemical

Other Communication Modes: pheromones

Perception Channels: visual ; tactile ; chemical

Eriocheir sinensis is not vulnerable, threatened, or endangered on any part of its native or introduced range.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

After the fertilized eggs hatch, they are called zoea and do not look like adults. Zoea have a long dorsal spine, a rostral spine, and 2 lateral spines. They develop appendages on their side that will eventually be involved in feeding. In this stage, they spend 1 to 2 months in brackish water before migrating upstream for further development. After 5 zoeal stages, the crab undergoes metamorphosis from the zoeal stage to a megalopal stage. At this stage, the larvae begin to look like adults but are still distinguishable from them because of the presence of a protruding abdomen. After about 7 days in this stage, molting occurs and juvenile crabs emerge; they then migrate upstream and go on to develop into adults, where sexual maturity is reached between their fourth and fifth years of life.

Development - Life Cycle: metamorphosis

When the mitten crabs invade, they can damage the riverbanks because of their burrowing behavior as mentioned in the Ecosystem Roles section. This could be a financial problem if development along the riverbank is threatened. Mitten crabs cause damages to commercial fishing nets. They could also eat the trapped fish in commercial ponds. Crabs damage crops in China by consuming rice shoots. Humans can become infected with Paragonimus ringeri by eating poorly cooked or raw mitten crabs.

Negative Impacts: injures humans (causes disease in humans ); crop pest

Mitten crabs are a delicacy in Asia and other places. They can be used as bait for eel fishing, in the production of cosmetic products, and as fertilizer in agriculture.

Positive Impacts: food

Mitten crabs are prey for many animals. They are also a secondary intermediate host of the Oriental lung fluke -- Paragonimus ringeri. Mammals including humans are the final host of this parasite. Mitten crabs can tolerate a wide range of environmental conditions. This is evident as this species has been spread via shipping to North America as well as Europe. When they are introduced to a new environment, their population becomes very large very fast and they change the structure of the local environment. For instance during migration, mitten crabs burrow into sediment and this increases erosion that can lead to collapse of river banks. They may also have a profound effect on biological communities through predation and competition.

Ecosystem Impact: creates habitat; soil aeration

Species Used as Host:

• Paragonimus ringeri

Mitten Crabs are omnivores, which means that they eat both plants and animals as its primary food source. As juveniles they mostly eat vegetation but also prey on small invertebrates

Animal Foods: other marine invertebrates

Plant Foods: algae

Other Foods: detritus

Primary Diet: omnivore

Chinese mitten crabs are found on coasts from Japan to the mainland of China, Korean Peninsula, and along the Yellow Sea; they are also found on the coasts of northern and eastern Europe and the United States.

Biogeographic Regions: nearctic (Introduced ); palearctic (Introduced , Native )

Chinese mitten crabs spend most of their lives in brackish water and freshwater rivers and estuaries. Eriocheir sinensis migrates downstream to saltwater environments to reproduce. During migration they are known to cross terrestrial boundaries, but they do not spend much time on land.

Habitat Regions: temperate ; saltwater or marine ; freshwater

Aquatic Biomes: rivers and streams; coastal ; brackish water

There are varied reports as to the lifespan of this species. Factors influencing the lifespan include temperature of the water, salinity, and others. Reports vary from lifespan as little as 1-2 years to as much as 3-5 years, depending on the region in which the crabs are located.

Range lifespan
Status: wild: 1 to 5 years.

Chinese mitten crabs are light brown and have hairy claws that are typically white-tipped, giving the appearance of mittens. They have a notch between the eyes and 4 lateral carapace spines. Their legs are generally twice as long as the width of the carapace, which has an average maximum width of 80 mm. Males and females are dimorphic: males have a V-shaped abdomen whereas the females have a U-shaped abdomen.

Other Physical Features: ectothermic ; bilateral symmetry

Sexual Dimorphism: sexes shaped differently

Mitten Crabs are subject to predation by many carnivorous organisms in the water and on land, including fish, frogs, and birds.

Known Predators:

• sunfish
• river otter
• raccoon

During the summer months mature Chinese mitten crabs begin their migration to the sea, with males arriving first and females arriving afterwards. Soon after reproduction, however, both sexes die and the progeny are left to fend for themselves.

Mating System: monogamous

Males and females come in contact and after initially fighting, mating behavior begins. During physical contact, males are able to recognize reproductively active females because the females release contact pheromones; they are only released after physical contact has been made.

Breeding season: Summer

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); oviparous

Females aerate their eggs after they are fertilized so that nutrients can be passed from mother to baby. Females can produce anywhere between 250,000 to 1 million eggs, depending on the size of the female. After eggs have been fertilized, they are released about 1 day after mating and females then produce a substance that allow her eggs to adhere to part of her abdomen. Over the winter season, the females stay under deep water while the eggs develop.

Parental Investment: pre-hatching/birth (Provisioning: Female)

The Chinese mitten crab arrived in the German Weser River in 1912. Larvae hitched a ride with ships trading with China. A notable feature of this crab is the brown 'hair' on its claws. Adult animals live in fresh water. They migrate to sea to mate and lay their eggs. During their migration journey, they don't let much stand in their way. Sometimes, they cross over a dike or a road in massive numbers or decide to take a shortcut through a neighborhood. People are totally perplexed when they suddenly see a group of crabs walking through their garden. They are readily seen as giant spiders or aliens from out-of-space!

Native To: Pacific coast of China and Korea (NAS Database 2011)

Date of U.S. Introduction: 1991 (West Coast); 2005 (East Coast) (NAS Database 2011) Means of Introduction: Ballast water (also possibly through intentional releases) (Cohen and Carlton 1997) Impact: Interference with fish salvage operations, fish passage facilities, water treatment plants, power plants, and other facilities (Cohen and Weinstein 2001) Current U.S. Distribution: West Coast; Great Lakes; Chesapeake Bay (NAS Database map) Federally Regulated: Listed as injurious wildlife under the Federal Lacey Act, which makes it illegal in the U.S. to import, export, or transport between States without a permit (DOI, Fish and Wildlife Service) Source: USDA, National Invasive Species Information Center

The Chinese mitten crab already appears in Belgium from 1933. The crab originates from the Far East and was presumably brought to Europe as a larva in the ballast water of ships. From Germany, the species spread through Northern- and Western-Europe. The Chinese mitten crab Eriocheir sinensis predominantly lives in rivers, but migrates seaward in the late summer to breed in the brackish part of the estuaries. The egg-carrying females spend the winter at sea, and return to the brackish part of the estuary in spring to release the larvae in the water which then develop to juvenile crabs. These juveniles migrate back up the rivers, streams and canals to complete the life cycle.

Deze krab met wollige scharen komt reeds vanaf 1933 in België voor. Deze krab is oorspronkelijk afkomstig uit het Verre Oosten en werd vermoedelijk meegebracht naar Europa als larve in ballastwater van schepen. Vanuit Duitsland heeft de soort zich verspreid doorheen Noord- en West-Europa. De Chinese wolhandkrab leeft voornamelijk in rivieren, maar trekt in de late zomer zeewaarts om te broeden in het brakke deel van riviermondingen. De eierdragende wijfjes brengen de winter door in zee en komen in de lente terug naar het brakke deel van estuaria om er de larven in het water vrij te laten en verder te laten ontwikkelen tot juveniele krabbetjes. Later trekken deze dan weer geleidelijk de rivier, stromen en kanalen op, waar ze hun levenscyclus voltooien.

Introduced to Europe in 1912 by shipping trade with China. A pest species, causing damage to river banks and fishing nets.

The species spends most of its time in freshwater, but has to return to the sea for reproduction.