Triangular vortex worm
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Triangular vortex worm ( Dugesia gonocephala ) |
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| ( Dugès , 1830) |
The triangular vortex worm ( Dugesia gonocephala ), also known as the triangular head vortex worm or European stream planaria , is a vortex worm of the genus Dugesia . It is widespread in the low mountain ranges and the Alps and lives preferably in fast-flowing, clean waters.
features
It becomes up to 25 mm long and 6 mm wide. Its body is solid brown to gray-brown. Compared to other types of Dugesia , its head is arrowhead-shaped, pointed at the front with angular side lobes, overall a triangular appearance (hence the name triangular vortex worm ). There are two large black eyes on the head, surrounded by a bright courtyard. The distance between the eyes is about the same as their distance from the front edge of the head.
habitat
The triangular vortex worm lives in streams (limnological zone of the Rhithral ), rarely also in springs and in river upper reaches ( Epipotamal ), it is flow-loving (rheophile). Often several specimens sit on the underside of large stones. It is sensitive to water pollution, which is why it plays a role in determining the water quality. With the saprobic index of 1.5, it is an indicator of the water quality class “low pollution”. Its occurrence joins the alpine vortex worm downstream from the source .
Dugesia gonocephala only tolerates alkaline and neutral waters and is sensitive to aquatic acidification. The lowest tolerated pH is between 6.0 and 6.4.
food
The main food of the triangular vortex worm consists of smaller aquatic animals such as B. small crustaceans, worms and insect larvae. The animal is able to perceive chemical stimuli via the lateral tactile organs in order to find prey. It is enclosed in a proboscis-like throat ( pharynx ) and digested outside with the help of digestive enzymes . The mouth opening is on the abdomen in the middle of the animal.
Taxonomy
The species was of Duges by animals from Montpellier (France) as Planaria gonocephala first described . It is a type of the genus Dugesia . The species lives in Central and Northern Europe. A number of very similar, closely related species occur in the Mediterranean, including some asexually reproducing (through fissiparia ). The species also differ partly in their karyology : while Dugesia gonocephala s.str. is diploid , some of the related species are triploid . Some of the species are morphologically indistinguishable, others can only be differentiated by details of the male copulation apparatus (since the fissiparous populations do not develop these, they cannot be morphologically assigned to any of the small species). Many of the small species have only narrowly circumscribed areas, the small species Dugesia sicula is more common . The entire kin group is circumscribed as a superspecies . The small species are sometimes differentiated using DNA barcoding . Fissiparie in Dugesia gonocephala s. st. does not occur, the species reproduces sexually. Like almost all flatworms, they are (simultaneous) hermaphrodites .
The copulation is preceded by a mating prelude to this species. If an individual encounters a suitable partner, the partner flattens extremely and takes on an oval body shape. The animal crawls on the partner's back (in a parallel orientation), where mating takes place soon afterwards, with both partners inserting their penis into the sexual opening of the other, thereby transferring a spermatophore . After mating, the animals lay eggs in a cocoon that is attached to a hard substrate on the bottom of the water.
Individual evidence
- ↑ World Register of Marine Species ( WoRMS )
- ↑ Steffen Pauls (2004): Annex 7 to Reynoldson & Young (2000): A Key to the Freshwater Triclads of Britain and Ireland with Notes on Their Ecology. Freshwater Biological Association Scientific Publication 58: 1-72. download at fliessgewaesserbassy.de
- ↑ Schmidt-Kloiber A. & Hering D. (editors) (2012): www.freshwaterecology.info - the taxa and autecology database for freshwater organisms, version 5.0 , accessed on June 30, 2014.
- ↑ DIN German Institute for Standardization eV (publisher): DIN 38410-1: German standard methods for water, waste water and sludge examination - biological-ecological water examination (group M) - part 1: Determination of the saprobic index in running waters (M 1) October 2004
- ↑ Hannes Schimmer and Günther Friedrich (1990): The effects of water acidification on the macrozoobenthon of selected low-mountain streams in the Sauerland and Siegerland. Lauterbomia 5: 49-66.
- ↑ Roman Kenk (1974): Index of the genera and species of the Freshwater Triclads (turbellaria) of the World. Smithsonian Contributions to Zoology Number 183.
- ^ Riutort M., Álvarez-Presas M., Lázaro E., Solà E., Paps J. (2012): Evolutionary history of the Tricladida and the Platyhelminthes: an up-to-date phylogenetic and systematic account. International Journal of Developmental Biology 56 (1-3): 5-17. doi : 10.1387 / ijdb.113441mr
- ^ Eva M. Lázaro, Ronald Sluys, Maria Pala, Giacinta Angela Stocchino, Jaume Baguñà, Marta Riutort (2009): Molecular barcoding and phylogeography of sexual and asexual freshwater planarians of the genus Dugesia in the Western Mediterranean (Platyhelminthes, Tricladida, Dugesiidae) . Molecular Phylogenetics and Evolution Volume 52, Issue 3: 835-845. doi : 10.1016 / j.ympev.2009.04.022
- ↑ C. Vreys, ER Schockaert, NK Michiels (1997): Formation, transfer, and assimilation of the spermatophore of the hermaphroditic flatworm Dugesia gonocephala (Tricladida, Paludicola). Canadian Journal of Zoology Vol. 75: 1479-1486.
- ↑ C. Vreys, ER Schockaert, MK Michels (1997): Unusual pre-copulatory behavior in the hermaphroditic planarian flatworm, Dugesia gonocepbala (Tricladida, Paludicola). Ethology 103: 208-221.
literature
- H. Bellmann: Life in Bach and Teich , Orbis Verlag, Munich 2000, ISBN 3-572-01085-3 .
- G.Kriska & T.Tittizer: Invertebrates in the inland waters of Central Europe , Weissdorn-Verlag, Jena 2009, ISBN 978-3-936055-58-0 .
Web links
- Digital nature photos of Dugesia gonocephala at Biopix
- Biography of the naturalist Dugès, Antoine Louis