Craspedacusta sowerbyi (alternatively C. sowerbii), or freshwater jellyfish, are freshwater animals in the Class hydrozoa. Contrary to what the common name implies, C. sowerbyi is not a true jellyfish, but a hydrozoan, making it more closely related to hydras. Unlinke true marine jellyfish, C. sowerbii has a structure called a velum on its ventral surface. C. sowerbii is found throughout the world in freshwater bodies of water. Scientific classification or biological classification is how biologists group and categorize extinct and living species of organisms. ... Phyla Porifera (sponges) Ctenophora (comb jellies) Cnidaria (coral, jellyfish, anemones) Placozoa (trichoplax) Subregnum Bilateria (bilateral symmetry) Acoelomorpha (basal) Orthonectida (parasitic to flatworms, echinoderms, etc. ... Classes Anthozoa - Corals and sea anemones Cubozoa - Sea wasps or box jellyfish Hydrozoa - Hydroids, hydra-like animals Scyphozoa - Jellyfish Cnidaria is a phylum containing some 10,000 species of relatively simple animals found exclusively in aquatic environments (most species are marine). ... Orders Actinulida Capitata Chondrophora Filifera Hydroida Siphonophora Trachylina Organisms that are in Class Hydrozoa come from the Phylum Cnidaria. ... Suborders Anthomedusae Hydrida Leptomedusae Limnomedusae Hydroida is a cnidarian order which includes hydras, hydromedusae, and many marine attached hydroids, many of which grow up into large, elegantly branched forms. ... In biology, binomial nomenclature is the formal method of naming species. ... Sir Edwin Ray Lankester (1847 - 1929) was a British zoologist. ... The word Animals when used alone has several possible meanings in the English language. ... Scientific classification or biological classification refers to how biologists group and categorize extinct and living species of organisms. ... Orders Actinulida Capitata Chondrophora Filifera Hydroida Siphonophora Trachylina Organisms that are in Class Hydrozoa come from the Phylum Cnidaria. ... Orders Stauromedusae Coronatae Semaeostomeae Rhizostomae Jellyfish are marine invertebrates belonging to the Scyphozoa class, and in turn the phylum Cnidaria. ... Species Hydra americana Hydra attenuata Hydra canadensis Hydra carnea Hydra cauliculata Hydra circumcincta Hydra hymanae Hydra littoralis Hydra magnipapillata Hydra minima Hydra oligactis Hydra oregona Hydra pseudoligactis Hydra rutgerensis Hydra utahensis Hydra viridis Hydra is the genus name of a simple, fresh-water animal possessing radial symmetry. ... This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... In zootomy, several terms are used to describe the location of organs and other structures in the body of bilateral animals. ...

Form

Freshwater jellyfish are about the size of a quarter (20–25 mm) when fully grown. They are shaped like an umbrella and have 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 called gonads. The tentacles contain hundreds of cells called Cnidocytes, which contain nematocysts, and are used to capture prey. Tentacles can refer to the elongated flexible organs that are present in many invertebrates, and sometimes to the hairs of the leaves of insectivorous plants. ... In optics, transparency is the property of being transparent, or allowing light to pass. ... A sex organ, or primary sexual characteristic, narrowly defined, is any of those parts of the body (which are not always bodily organs according to the strict definition) which are involved in sexual reproduction and constitute the reproductive system in an complex organism; namely: Male: penis (notably the glans penis... Cnidocytes are prey-capture and defensive cells found on animals of the phylum Cnidaria. ... Cnidocytes are prey-capture and defensive cells unique to animals of the phylum Cnidaria. ...

Habitat

C. sowerbii is usually found in calm, freshwater reservoirs, lakes, 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. They prefer standing water, and are not generally seen in fast flowing streams or rivers. For the village on the Isle of Wight, see Freshwater, Isle of Wight. ... A reservoir (French: réservoir) is an artificial lake created by flooding land behind a dam. ... Lake Clearwater, Ontario, Canada A lake is a large body of water, usually fresh water, surrounded by land. ... This entry incorporates text from Eastons Bible Dictionary, 1897, with some modernisation. ... The Allegheny River (historically, especially in New York state, also spelled Allegany River) is a principal tributary of the Ohio River, which it forms with the Monongahela River at the downtown Pittsburghs Golden Triangle point. The river is approximately 325 mi (523 km) long, in the U.S. states... Ohio River viewed from Liberty Hill in Ripley, Ohio. ... A riverboat passing under the Gay Street Bridge on the Tennessee River The river viewed from the top of Neyland Stadium. ...

Feeding

C. sowerbii is a predator on zooplankton including Daphnia and copepods. Prey is caught with their stinging tentacles. Drifting with it's tentacles extended, the jellyfish 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. Photomontage of plankton organisms Plankton is the aggregate community of weakly swimming but mostly drifting small organisms that inhabit the water column of the ocean, seas, and bodies of freshwater. ... Species Subgenus Daphnia Subgenus Hyalodaphnia Subgenus Ctenodaphnia Daphnia are small, mostly planktonic, crustaceans, between 0. ... Orders Calanoida Cyclopoida Gelyelloida Harpacticoida Misophrioida Monstrilloida Mormonilloida Platycopioida Poecilostomatoida Siphonostomatoida Copepods are small, aquatic animals living in the sea and nearly every freshwater habitat, a form of plankton, specifically zooplankton, some copepods are parasitic. ... The skull and crossbones symbol traditionally used to label a poisonous substance. ...

Natural history

C. sowerbii begins life as a tiny polyp, which lives in colonies attached to underwater vegetation, rocks, or tree stumps, feeding and asexually reproducing during spring and summer. Some of these offspring are the sexually-reproducing medusae. Fertilized eggs develop into small ciliated larvae called planula. The planula then settle to the bottom, and develop into polyps. However, the majority of C. sowerbii 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 bodies, called podocysts. 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 zoology, a polyp is one of two forms of individuals found in many species of cnidarians. ... Asexual reproduction in liverworts: a caducuous phylloid germinating Asexual reproduction (also known as agamogenesis) is a form of reproduction which does not involve meiosis, gamete formation, or fertilization. ... Sexual reproduction is a type of reproduction that results in increasing genetic diversity of the offspring. ... A relatively modern image of Medusa painted by Arnold Böcklin In Greek mythology, Medusa (Greek: Μέδουσα), was a monstrous female character whose gaze could turn people to stone. ... A larva (Latin; plural larvae) is a juvenile form of animal with indirect development, undergoing metamorphosis (for example, insects or amphibians). ... A planula is the free-swimming, flattened, ciliated, bilaterally symmetrical larva of a hydrozoan cnidarian. ...

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