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

hydrozoa Hydrozoa (hydrozoans; from Ancient Greek ('; "water") and ('; "animals")) is a taxonomy (biology), taxonomic class (biology), class of individually very small, predatory animals, some solitary and some colonial, most of which inhabit saline wat ...

n jellyfish, or hydromedusa

cnidaria Cnidaria ( ) is a phylum under kingdom Animalia containing over 11,000 species of aquatic invertebrates found both in fresh water, freshwater and marine environments (predominantly the latter), including jellyfish, hydroid (zoology), hydroids, ...

n. Hydromedusan jellyfish differ from scyphozoan jellyfish because they have a muscular, shelf-like structure called a velum on the ventral surface, attached to the bell margin. Originally from the Yangtze basin in China, ''C. sowerbii'' is an

introduced species An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived ther ...

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 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, with a whitish or greenish tinge. The (usually) four large flat sex organs ( gonads) are attached to the four radial canals, and are usually opaque white. The many tentacles each contain thousands of cells called cnidocytes, which contain nematocysts (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 Yangtze basin in China, but has been introduced on every continent except for Antarctica. It is usually found in calm, freshwater

reservoir A reservoir (; ) is an enlarged lake behind a dam, usually built to water storage, store fresh water, often doubling for hydroelectric power generation. Reservoirs are created by controlling a watercourse that drains an existing body of wa ...

s, lakes, impoundments, gravel pits or quarries. It has also been seen in slow-moving backwaters of river systems such as the Allegheny River, the

Ohio River The Ohio River () is a river in the United States. It is located at the boundary of the Midwestern and Southern United States, flowing in a southwesterly direction from Pittsburgh, Pennsylvania, to its river mouth, mouth on the Mississippi Riv ...

and the

Tennessee River The Tennessee River is a long river located in the Southern United States, southeastern United States in the Tennessee Valley. Flowing through the states of Tennessee, Alabama, Mississippi, and Kentucky, it begins at the confluence of Fren ...

in the United States and the Wang Thong River of

Thailand Thailand, officially the Kingdom of Thailand and historically known as Siam (the official name until 1939), is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. With a population of almost 66 million, it spa ...

. 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.

Asia

Since 2008 the freshwater jellyfish have been sighted every September and October in the Zhaojiaya Reservoir near Zhangjiajie,

Hunan Hunan is an inland Provinces of China, province in Central China. Located in the middle reaches of the Yangtze watershed, it borders the Administrative divisions of China, province-level divisions of Hubei to the north, Jiangxi to the east, Gu ...

, China. It has been found in the Cauvery River and backwaters of the Hemavathi River in

Karnataka Karnataka ( ) is a States and union territories of India, state in the southwestern region of India. It was Unification of Karnataka, formed as Mysore State on 1 November 1956, with the passage of the States Reorganisation Act, 1956, States Re ...

, India. It is also found in the Bang Rachan rapids forest on the Khek River, the upstream of the Wang Thong River in Khao Kho District, Phetchabun Province, where it is the provincial aquatic life. Freshwater jellyfish can only be seen around early March to May, which is the summer.

Australia

It has been found in water reservoirs and artificial lakes in south-eastern Australia, including the Thorndon Park reservoir and Lake Burley Griffin.

Europe

During the abnormal heat in the summer 2010 in Russia sightings of ''C. sowerbii'' were reported in the Moscow River. It has been found in several lakes in

Hungary Hungary is a landlocked country in Central Europe. Spanning much 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 south, Croatia and ...

. They also live in Lake Geneva between Switzerland and France.

North America

On August 21, 2010, ''C. sowerbii'' was spotted and captured on the northwest corner of Falcon Lake in

Manitoba Manitoba is a Provinces and territories of Canada, province of Canada at the Centre of Canada, longitudinal centre of the country. It is Canada's Population of Canada by province and territory, fifth-most populous province, with a population ...

, Canada. Scientists believe this was due to a

heat wave A heat wave or heatwave, sometimes described as extreme heat, is a period of abnormally hot weather generally considered to be at least ''five consecutive days''. A heat wave is usually measured relative to the usual climate in the area and ...

in the Whiteshell Provincial Park area. It is proposed the ''C. sowerbii'' came to Falcon Lake on waterfowl originating from Star Lake, Manitoba, Canada. Falcon Lake along with Star Lake remain the only two confirmed sightings of ''C. sowerbii'' in Manitoba. It has been found in British Columbia in 34 lakes as far north as Cache Creek and Port Hardy. ''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). Populations are also known to exist in several lakes in Minnesota ''C. sowerbii'' was found and collected by the Sternberg Museum of Natural History in Melvern Lake in Kansas in 2020. In July 2022, a population was discovered in a pond at Shawnee Park in

Louisville, Kentucky Louisville is the List of cities in Kentucky, most populous city in the Commonwealth of Kentucky, sixth-most populous city in the Southeastern United States, Southeast, and the list of United States cities by population, 27th-most-populous city ...

South and Central America

It was reported in Panama in 1925, Chile in 1942, Argentina in 1950, Brazil in 1963, and in Uruguay in 1971.

Feeding

''C. sowerbii'' 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

venom Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved ''venom apparatus'', such as fangs or a sti ...

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 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 medusae. Fertilized eggs develop into small ciliated

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

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

External links

USGS' page about ''C. sowerbyi''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