Craspedacusta sowerbyi
4119998
224490246
2008-07-09T02:12:28Z
Dysmorodrepanis
303688
they are not called sowerbii and thery are not jellyfish
{{Taxobox
| name = Freshwater Jelly
| image = Craspedacusta sowerbyii.jpg
| image_width = 220px
| regnum = [[Animal]]ia
| subregnum = [[Eumetazoa]]
| phylum = [[Cnidaria]]
| subphylum = [[Medusozoa]]
| classis = [[Hydrozoa]]
| subordo = [[Limnomedusae]]
| familia = [[Olindiidae]]
| genus = ''[[Craspedacusta]]''
| species = '''''C. sowerbyi'''''
| binomial = ''Craspedacusta sowerbyi''
| binomial_authority = [[Ray Lankester|Lankester]], 1880
| synonyms =
''Craspedacusta sowerbii'' (''[[lapsus]]'')
}}
'''''Craspedacusta sowerbyi''''', the '''Freshwater Jelly''' or (erroneously) '''"freshwater jellyfish"''', is a [[species]] of freshwater [[animal]] in the [[phylum (biology)|phylum]] [[Cnidaria]]. ''C. sowerbyi'' is not a true [[jellyfish]] but a [[hydrozoa]]n [[meduse (biology)|medusoid]] jelly more closely related to [[Hydra (genus)|hydras]]. Unlike true marine jellyfish, ''C. sowerbyi'' has a structure called a [[velum]] on its [[ventral]] surface. ''C. sowerbyi'' is found throughout the world in freshwater bodies of water.
==Form==
Freshwater jellies are about 20 - 25 mm in diameter when fully grown. They are found in medusa form and have a whorl of [[tentacles]] around their [[ring canal]]. Most of the body is [[translucent]] with a whitish or greenish tinge, with the exception of large flat sex organs ([[gonads]]). The tentacles contain hundreds of cells called [[Cnidocytes]], which contain [[nematocysts]], and are used to capture prey.
==Habitat==
''C. sowerbyi'' is usually found in calm, [[freshwater]] [[reservoir (water)|reservoir]]s, [[lake]]s, impoundments, gravel pits or [[quarries]]. They have also been seen in river systems such as the [[Allegheny River]], the [[Ohio River]] and the [[Tennessee River]] in the [[United States]] and the [[Wang Thong River]] of [[Thailand]]. They prefer standing water, and are not generally seen in fast flowing streams or rivers.
===Expanding range in North America===
Originally thought to have not lived in [[Arkansas]], on 9-22-07 they were discovered in a lake in [[Eureka Springs, Arkansas]]. The sole record to date (April 2008) for this hydrozoan in [[Oregon]] is the [[Tualatin River]] drainage, a slow moving, highly eutrophic system southwest of [[Portland, Oregon|Portland]]. They appear to be relatively rare in the [[Pacific Northwest]] as they have not been found elsewhere in over 500 lakes sampled in Oregon and western [[Washington]].
==Feeding==
''C. sowerbyi'' is a predator on [[zooplankton]] including [[daphnia]] and [[copepods]]. Prey is caught with their stinging tentacles. Drifting with its tentacles extended, the jelly waits for suitable prey to touch a tentacle. Once contact has been made, nematocysts on the tentacle fire into the prey, injecting [[poison]] which paralyzes the animal, and the tentacle itself coils around the prey. The tentacles then bring the prey into the mouth, where it is digested.
==Natural history==
''C. sowerbyi'' begins life as a tiny [[polyp]], which lives in colonies attached to underwater vegetation, rocks, or tree stumps, feeding and [[asexual reproduction|asexually reproducing]] during spring and summer. Some of these offspring are the [[sexual reproduction|sexually reproducing]] [[medusa]]e. Fertilized eggs develop into small ciliated [[larva]]e called [[planula]]. The planula then settle to the bottom, and develop into polyps. However, the majority of ''C. sowerbyi'' populations existing in the United states are either all male or all female, so there is no sexual reproduction in those populations.
During the cold winter months, polyps contract and become [[resting body|resting bodies]], called [[podocyst]]s. It is believed that podocysts are transported by aquatic plants or animals to other bodies of water. Once conditions become favorable, they develop into polyps again.
The medusa appearance is sporadic and unpredictable. Often, they will appear in a body of water where they had never been documented before in very large numbers, and they may be even reported on the news. In parts of the mid-west and the great lakes area, seeing one is considered to be a sign of good luck.
==External links==
*http://www.jellyfish.iup.edu/index.html
*http://www.microscopy-uk.org.uk/mag/artdec99/fwjelly2.html
*http://www.microscopy-uk.org.uk/mag/artnov99/fwjelly.html
*[http://www.tourismthailand.org/destinationguide/list.aspx?provinceid=54&typeid=7 Kaeng Bang Rachan at Tourism Authority of Thailand] (reference to freshwater jellyfish in the Wang Thong River in Thailand)
[[Category:Hydrozoa]]
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[[it:Craspedacusta sowerbyi]]
[[ja:マミズクラゲ]]