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. ("Eriocheir Sinensis (Milne Edwards, 1853)", 2003; Gollasch, 2006)
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. ("Mitten Crab Projects", 2007)
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. ("Chinese Mitten Crab: Life and History", 1998; Gollasch, 2006; Metzler, 1998; Robbins, et al., 2007)
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. ("Chinese Mitten Crab: Life and History", 1998; "Eriocheir Sinensis (Milne Edwards, 1853)", 2003; Rainbow, et al., 2003)
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. ("Chinese Mitten Crab: Life and History", 1998)
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. (Herborg, et al., 2006)
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. ("Chinese Mitten Crab: Life and History", 1998; Rainbow, et al., 2003; Robbins, et al., 2007)
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. ("National Management Plan For the Genus Eriocheir (Mitten Crabs)", 2003)
Eriocheir sinensis is catadromous: adult Mitten Crabs live in fresh water, but migrate to salt water for reproduction. It is not clear how the crabs communicate during their migration, but it is speculated that there is an environmental cue, which triggers the migration. They are adept walkers and during migration are able to walk on banks and over other obstacles when needed. The offspring are also motile – as the zoea develop in the salt water, they gain the morphologic characteristics of the adult. Legs are developed which allow the juvenile crab to migrate upriver towards brackish water and finally to fresh water environment. ("Chinese Mitten Crab: Life and History", 1998)
In fresh water the juvenile crabs burrow into the banks in order to escape predators and desiccation. Burrows are more extensive in tidal areas because when tide is low threats are greater. ("Chinese Mitten Crab: Life and History", 1998; Metzler, 1998)
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. (Herborg, et al., 2006)
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 ("Chinese Mitten Crab: Life and History", 1998)
Mitten Crabs are subject to predation by many carnivorous organisms in the water and on land, including fish, frogs, and birds. ("Chinese Mitten Crab: Life and History", 1998)
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. ("Eriocheir Sinensis (Milne Edwards, 1853)", 2003; Clark and Hemsley-Flint, 2007; Gollasch, 2006)
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. (Clark and Hemsley-Flint, 2007; Gollasch, 2006)
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. ("Chinese Mitten Crab: Life and History", 1998; Clark and Hemsley-Flint, 2007)
Eriocheir sinensis is not vulnerable, threatened, or endangered on any part of its native or introduced range.
Anna Solovyeva (author), Rutgers University, Kyle Bailey (author), Rutgers University, David Howe (editor, instructor), Rutgers University .
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
areas with salty water, usually in coastal marshes and estuaries.
an animal which directly causes disease in humans. For example, diseases caused by infection of filarial nematodes (elephantiasis and river blindness).
uses smells or other chemicals to communicate
the nearshore aquatic habitats near a coast, or shoreline.
particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
union of egg and spermatozoan
A substance that provides both nutrients and energy to a living thing.
mainly lives in water that is not salty.
fertilization takes place within the female's body
referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.
A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.
makes seasonal movements between breeding and wintering grounds
Having one mate at a time.
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
an animal that mainly eats all kinds of things, including plants and animals
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
chemicals released into air or water that are detected by and responded to by other animals of the same species
mainly lives in oceans, seas, or other bodies of salt water.
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
digs and breaks up soil so air and water can get in
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
uses sight to communicate
1998. "Chinese Mitten Crab: Life and History" (On-line). Accessed October 13, 2007 at http://www.delta.dfg.ca.gov/mittencrab/life_hist.asp.
2003. "Eriocheir Sinensis (Milne Edwards, 1853)" (On-line). Accessed October 13, 2007 at http://nis.gsmfc.org/nis_factsheet.php?toc_id=132.
2007. "Mitten Crab Projects" (On-line). Accessed October 13, 2007 at http://www.clr.pdx.edu/projects/ans/mittencrab.php.
Aquatic Nuisance Species Task Force. National Management Plan For the Genus Eriocheir (Mitten Crabs). 2003. Accessed November 09, 2007 at http://www.anstaskforce.gov/control.php.
Clark, P., B. Hemsley-Flint. 2007. "Eriocheir Sinensis" (On-line). Accessed October 13, 2007 at http://www.jncc.gov.uk/page-1709.
Gollasch, S. 2006. "Eriocheir Sinensis (Crustacean)" (On-line). Accessed October 13, 2007 at http://www.issg.org/database/species/ecology.asp?si=38&fr=1&sts=.
Herborg, L., M. Bentley, A. Clare, K. Last. 2006. Mating Behaviour and Chemical Communication in the Invasive Chinese Mitten Crab Eriocheir sinensis. Journal of Experimental Marine Biology and Ecology, 329: 1-10. Accessed October 13, 2007 at http://web2.uwindsor.ca/courses/biology/macisaac/pages/JEMBE.pdf.
Metzler, J. 1998. "Chinese Mitten Crab (Eriocheir Sinensis)" (On-line). Accessed October 13, 2007 at http://www.iisgcp.org/exoticsp/Chinese_Mitten_Crab.htm.
Rainbow, P., R. Roni, P. Clark. 2003. Alien invaders: Chinese mitten crabs in the Thames and spreading. Biologist, Volume 50/Issue 5: 227-230. Accessed October 31, 2007 at http://web.ebscohost.com/ehost/pdf?vid=5&hid=5&sid=497b8b4e-4eeb-4a84-9500-8dd7e22cd466%40sessionmgr7.
Robbins, R., P. Clark, P. Rainbow. 2007. "Mitten Crabs: Oriental Invaders of the River Thames" (On-line). Accessed October 13, 2007 at http://www.nhm.ac.uk/nature-online/life/other-invertebrates/chinese-mitten-crabs/chinese-mitten-crabs.html.