Eriocheir sinensisChinese mitten crab

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Geographic Range

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)

Habitat

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)

Physical Description

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)

  • Sexual Dimorphism
  • sexes shaped differently

Development

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)

Reproduction

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)

  • Breeding season
    Summer

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)

  • Parental Investment
  • pre-hatching/birth
    • provisioning
      • female

Lifespan/Longevity

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)

  • Range lifespan
    Status: wild
    1 to 5 years

Behavior

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)

Communication and Perception

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)

Food Habits

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)

  • Animal Foods
  • other marine invertebrates
  • Plant Foods
  • algae

Predation

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)

  • Known Predators
    • sunfish
    • river otter
    • raccoon

Ecosystem Roles

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)

Species Used as Host
  • Paragonimus ringeri

Economic Importance for Humans: Positive

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)

  • Positive Impacts
  • food

Economic Importance for Humans: Negative

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)

Conservation Status

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

Contributors

Anna Solovyeva (author), Rutgers University, Kyle Bailey (author), Rutgers University, David Howe (editor, instructor), Rutgers University .

Glossary

Nearctic

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.

World Map

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

bilateral symmetry

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.

brackish water

areas with salty water, usually in coastal marshes and estuaries.

causes disease in humans

an animal which directly causes disease in humans. For example, diseases caused by infection of filarial nematodes (elephantiasis and river blindness).

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

detritus

particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

fertilization

union of egg and spermatozoan

food

A substance that provides both nutrients and energy to a living thing.

freshwater

mainly lives in water that is not salty.

internal fertilization

fertilization takes place within the female's body

introduced

referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.

metamorphosis

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.

migratory

makes seasonal movements between breeding and wintering grounds

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

omnivore

an animal that mainly eats all kinds of things, including plants and animals

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

soil aeration

digs and breaks up soil so air and water can get in

tactile

uses touch to communicate

temperate

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).

visual

uses sight to communicate

References

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.