Freshwater jellyfish
Freshwater jellyfish | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Freshwater jellyfish |
||||||||||||
Systematics | ||||||||||||
|
||||||||||||
Scientific name | ||||||||||||
Craspedacusta sowerbii | ||||||||||||
Lankester , 1880 |
The freshwater jellyfish ( Craspedacusta sowerbii , wrongly also C. sowerbyi , C. sowerbyii or Microhydra sowerbyi ), also called freshwater meduse, is a species of Limnomedusae from the cnidarians . At 99.3%, the freshwater jellyfish has the highest water content found in animals.
It is the only species of the genus Craspedacusta that occurs in freshwater and has spread beyond East Asia . It occurs in slowly flowing and stagnant waters, in which the bank zone can warm up strongly. The preferred diet consists of small crabs , rotifers and protozoa .
Freshwater jellyfish are harmless to humans and have nothing to do with poor water quality.
features
The diameter is up to 2.5 cm. The adult animal has up to 600 nettle-covered, thread-like tentacles on the edge of the umbrella. The stomach stalk ends in four mouth lobes. In sexually mature animals, there is one genital organ on each of the radial canals emanating from the central stomach.
biology
The polyp from which the jellyfish ( medusa ) emerges by budding is very small (0.5 to 2 mm) and tentacles . The medusa as a sex form of the cnidarians reproduces sexually, which causes polyps again.
The freshwater jellyfish species Craspedacusta sowerbii, which occurs in Europe (mostly) does not reproduce sexually, as the polyps introduced by birds are almost always same-sex. The polyps multiply asexually by budding, transverse division or by frustration. The polyps then give rise to same-sex medusas that cannot reproduce sexually because they lack the other sexual partner.
distribution
The first European evidence was made in 1880 by James de Carle Sowerby in the Royal Botanic Gardens in London, where they appeared in a water lily pool. It is believed that they were introduced from Brazil. Alternatively, Craspedacusta sowerbii could have been introduced to Europe from East Asia in 1880 . Today the species can be found worldwide, except in Antarctica.
supporting documents
Individual evidence
- ↑ World Hydrozoa Database - Craspedacusta sowerbii
- ↑ Herbert W. Ludwig: Animals and plants of our waters. Characteristics, biology, habitat, endangerment , BLV Verlag, ISBN 978-3-405-16487-4
- ↑ a b NOBANIS - Invasive Alien Species Fact Sheet: Craspedacusta sowerbyi (English, accessed on November 13, 2016; PDF; 180 kB)
- ↑ Profile of fresh water meduse at neobiota.info (accessed on November 13, 2016)
- ^ Mario Ludwig et al.: New animals and plants in native nature ISBN 3-405-15776-5
- ↑ Lexicon of Biology, Elsevier, 1st edition 2004
literature
- Edwin Ray Lankester : On Limnocodium (Craspedacustes) Sowerbii, a new Trachomedusa inhabiting Fresh Water. Quarterly Journal of Microscopical Science, 20: 351-371, London 1880 PDF .
Web links
- Video of a freshwater jellyfish in the Feldkirch bathing lake
- Video: Craspedacusta sowerbii - polyp colonies and formation of wandering frustules . Institute for Scientific Film (IWF) 1956, made available by the Technical Information Library (TIB), doi : 10.3203 / IWF / B-714 .
- Video: Polyp colonies, wandering frustules and stages of development of the Medusa of Craspedacusta sowerbii . Institute for Scientific Film (IWF) 1975, made available by the Technical Information Library (TIB), doi : 10.3203 / IWF / D-1167 .
annotation
- ↑ The notation chosen by Lancester (1880) is sowerbii . It is the genitive form of the Latinized name Sowerbius. This notation is to be retained according to the International Rules for Zoological Nomenclature .