''Craspedacusta sowerbii'' or peach blossom jellyfish is a species of freshwater

hydrozoa Hydrozoa (hydrozoans; ) are a taxonomic class of individually very small, predatory animals, some solitary and some colonial, most of which inhabit saline water. The colonies of the colonial species can be large, and in some cases the specialize ...

n jellyfish, or hydromedusa

cnidaria Cnidaria () is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in freshwater and marine environments, predominantly the latter. Their distinguishing feature is cnidocytes, specialized cells that ...

n. Hydromedusan jellyfish differ from scyphozoan jellyfish because they have a muscular, shelf-like structure called a velum on the

ventral Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

surface, attached to the bell margin. Originally from the

Yangtze The Yangtze or Yangzi ( or ; ) is the longest river in Asia, the third-longest in the world, and the longest in the world to flow entirely within one country. It rises at Jari Hill in the Tanggula Mountains (Tibetan Plateau) and flows ...

basin in China, ''C. sowerbii'' is an invasive species now found throughout the world in bodies of fresh water.

Form

''C. sowerbii'' medusae are about 20–25 mm (approximately 1 in.) in diameter, somewhat flatter than a hemisphere, and very delicate, when fully grown. They have a whorl of up to 400

tentacles In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work mainl ...

tightly packed around the bell margin. Hanging down from the center of the inside of the bell is a large stomach structure called a manubrium, with a mouth-opening with four frilly lips. Circulation of nutrients is facilitated by four radial canals which originate at the edges of the stomach (manubrium), and which are also connected to a ring canal, located near the bell margin. Most of the body is transparent or

translucent In the field of optics, transparency (also called pellucidity or diaphaneity) is the physical property of allowing light to pass through the material without appreciable scattering of light. On a macroscopic scale (one in which the dimensions ...

, with a whitish or greenish tinge. The (usually) four large flat sex organs (

gonads A gonad, sex gland, or reproductive gland is a mixed gland that produces the gametes and sex hormones of an organism. Female reproductive cells are egg cells, and male reproductive cells are sperm. The male gonad, the testicle, produces sper ...

) are attached to the four radial canals, and are usually opaque white. The many tentacles each contain thousands of cells called

cnidocytes A cnidocyte (also known as a cnidoblast or nematocyte) is an explosive Cell (biology), cell containing one large secretory organelle called a cnidocyst (also known as a cnida () or nematocyst) that can deliver a sting to other organisms. The pre ...

, which contain

nematocysts A cnidocyte (also known as a cnidoblast or nematocyte) is an explosive cell containing one large secretory organelle called a cnidocyst (also known as a cnida () or nematocyst) that can deliver a sting to other organisms. The presence of this c ...

(also known as cnidocysts), and are used to capture prey and pass it to the mouth. Food is taken in the mouth opening, and waste is finally expelled out of the same opening.

Habitat and distribution

''C. sowerbii'' is native to the

basin in China, but has been introduced on every continent except for Antarctica. It can be found in most American states (no reports yet from

Montana Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Columb ...

Wyoming Wyoming () is a state in the Mountain West subregion of the Western United States. It is bordered by Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho to the west, Utah to the southwest, and Colorado to the s ...

North Dakota North Dakota () is a U.S. state in the Upper Midwest, named after the indigenous Dakota Sioux. North Dakota is bordered by the Canadian provinces of Saskatchewan and Manitoba to the north and by the U.S. states of Minnesota to the east, So ...

South Dakota South Dakota (; Sioux: , ) is a U.S. state in the North Central region of the United States. It is also part of the Great Plains. South Dakota is named after the Lakota and Dakota Sioux Native American tribes, who comprise a large porti ...

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S. ...

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only state ...

) and most Canadian provinces (no reports yet from

Alberta Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Ter ...

Saskatchewan Saskatchewan ( ; ) is a province in western Canada, bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and on the south by the U.S. states of Montana and North Dak ...

). It is usually found in calm, freshwater

reservoir A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including contro ...

s, lakes, impoundments, gravel pits or

quarries A quarry is a type of open-pit mine in which dimension stone, rock, construction aggregate, riprap, sand, gravel, or slate is excavated from the ground. The operation of quarries is regulated in some jurisdictions to reduce their envir ...

. It has also been seen in slow-moving backwaters of river systems such as the Allegheny River, the Ohio River and the

Tennessee River The Tennessee River is the largest tributary of the Ohio River. It is approximately long and is located in the southeastern United States in the Tennessee Valley. The river was once popularly known as the Cherokee River, among other name ...

in the United States and the

Wang Thong River The Wang Thong River ( th, แคววังทอง, , , also known as the ''Khek River'') is a river in Thailand. Its source lies in the Phetchabun Mountains in the Khao Kho District, Thailand.

Thailand Thailand ( ), historically known as Siam () and officially the Kingdom of Thailand, is a country in Southeast Asia, located at the centre of the Indochinese Peninsula, spanning , with a population of almost 70 million. The country is b ...

. It is not generally seen in fast flowing streams or rivers. The medusa's appearance is sporadic and unpredictable from year to year. It is not uncommon for ''C. sowerbii'' to appear in a body of water where it had never been documented before, in very large numbers, and its appearance may even be reported on the local news. On August 21, 2010, ''C. sowerbii'' was spotted and captured on the northwest corner of Falcon Lake in

Manitoba , image_map = Manitoba in Canada 2.svg , map_alt = Map showing Manitoba's location in the centre of Southern Canada , Label_map = yes , coordinates = , capital = Winn ...

, Canada. Scientists believe this was due to a

heat wave A heat wave, or heatwave, is a period of excessively hot weather, which may be accompanied by high humidity, especially in oceanic climate countries. While definitions vary, a heat wave is usually measured relative to the usual climate in the ...

in the

Whiteshell Provincial Park Whiteshell Provincial Park is a provincial park in southeast Manitoba, approximately east of the city of Winnipeg. The park is considered to be a Class II protected area under the IUCN protected area management categories. It is in size. ...

area. It is proposed the ''C. sowerbii'' came to Falcon Lake on

waterfowl Anseriformes is an order of birds also known as waterfowl that comprises about 180 living species of birds in three families: Anhimidae (three species of screamers), Anseranatidae (the magpie goose), and Anatidae, the largest family, which i ...

originating from Star Lake, Manitoba, Canada. Falcon Lake along with Star Lake remain the only two confirmed sightings of ''C. sowerbii'' in Manitoba. ''C. sowerbii'' has been seen in Pennsylvanian lakes and reservoirs including Marsh Creek Lake, Downingtown/Eagle, PA Turnpike/Rt 100/Rt 401, SR 282 (2007,2008). It has been found in water reservoirs and artificial lakes in south-eastern Australia, including the

Thorndon Park reservoir Thorndon Park Reserve is a public park in the Adelaide suburb of Paradise, South Australia, Paradise, South Australia. It was originally the site of the Thorndon Park reservoir, which was completed in 1860. The reserve became accessible to the pub ...

and

Lake Burley Griffin Lake Burley Griffin is an artificial lake in the centre of Canberra, the capital of Australia. It was completed in 1963 after the Molonglo River, which ran between the city centre and Parliamentary Triangle, was dammed. It is named after Wal ...

. It was reported in Panama in 1925, Chile in 1942, Argentina in 1950, Brazil in 1963, and in Uruguay in 1971. Since 2008 the freshwater jellyfish have been sighted every September and October in the Zhaojiaya Reservoir near

Zhangjiajie Zhangjiajie (), also known in Tujia language as ''Zhangx jif avlar'' /dzaŋ˩ ji˥ a˩.la˥/, is a prefecture-level city in the northwestern part of Hunan Province, China. It comprises the district of Yongding, Wulingyuan and counties of Cili ...

Hunan Hunan (, ; ) is a landlocked province of the People's Republic of China, part of the South Central China region. Located in the middle reaches of the Yangtze watershed, it borders the province-level divisions of Hubei to the north, Jiangxi ...

, China. It has been found in the

Cauvery River The Kaveri (also known as Cauvery, the anglicized name) is one of the major Indian rivers flowing through the states of Karnataka and Tamil Nadu. The Kaveri river rises at Talakaveri in the Brahmagiri range in the Western Ghats, Kodagu dist ...

and backwaters of the Hemavathi River in

Karnataka Karnataka (; ISO: , , also known as Karunāḍu) is a state in the southwestern region of India. It was formed on 1 November 1956, with the passage of the States Reorganisation Act. Originally known as Mysore State , it was renamed ''Karnat ...

, India and in several lakes in

Hungary Hungary ( hu, Magyarország ) is a landlocked country in Central Europe. Spanning of the Pannonian Basin, Carpathian Basin, it is bordered by Slovakia to the north, Ukraine to the northeast, Romania to the east and southeast, Serbia to the ...

. During the abnormal heat in the summer 2010 in Russia sightings of ''C. sowerbii'' were reported in the

Moscow River The Moskva (russian: река Москва, Москва-река, ''Moskva-reka'') is a river running through western Russia. It rises about west of Moscow and flows roughly east through the Smolensk and Moscow Oblasts, passing through centra ...

. In July 2022, a population was discovered in a pond at

Shawnee Park Shawnee Park is a municipal park in Louisville, Kentucky. It was designed by Frederick Law Olmsted, who designed 18 of the city's 123 public parks. Along with the rest of the city's Olmsted-designed park system, Shawnee Park was added to the Nati ...

Louisville, Kentucky Louisville ( , , ) is the largest city in the Commonwealth of Kentucky and the 28th most-populous city in the United States. Louisville is the historical seat and, since 2003, the nominal seat of Jefferson County, on the Indiana border ...

Feeding

''C. sowerbii'' is a predator on

zooplankton Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...

including

daphnia ''Daphnia'' is a genus of small planktonic crustaceans, in length. ''Daphnia'' are members of the order Anomopoda, and are one of the several small aquatic crustaceans commonly called water fleas because their saltatory swimming style resembl ...

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 released and then digested. Just like salt water jellyfish they do have stinging cells. However, these

cnidocyte A cnidocyte (also known as a cnidoblast or nematocyte) is an explosive cell containing one large secretory organelle called a cnidocyst (also known as a cnida () or nematocyst) that can deliver a sting to other organisms. The presence of this c ...

cells are used for paralyzing very tiny prey and have not been proven to have the capacity to pierce human skin.

Life cycle

''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

medusa In Greek mythology, Medusa (; Ancient Greek: Μέδουσα "guardian, protectress"), also called Gorgo, was one of the three monstrous Gorgons, generally described as winged human females with living venomous snakes in place of hair. Those ...

e. Fertilized eggs develop into small ciliated

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...

e called planulae. The planulae 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 enter dormancy as 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.

References

Romania

External links

*https://web.archive.org/web/20090922212421/http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=1068 USGS' page about ''C. sowerbyi'' *https://web.archive.org/web/20190719042938/http://freshwaterjellyfish.org/ An authoritative and detailed website about ''Craspedacusta sowerbyi'' *https://web.archive.org/web/20190721110836/http://www.microscopy-uk.org.uk/mag/artdec99/fwjelly2.html *https://web.archive.org/web/20190718162523/http://www.microscopy-uk.org.uk/mag/artnov99/fwjelly.html
Kaeng Bang Rachan at Tourism Authority of Thailand
(reference to freshwater jellyfish in the Wang Thong River in Thailand)
GLANSIS Species FactSheet
{{Authority control Olindiidae Animals described in 1880 Taxa named by Ray Lankester