Difference between revisions of "Gastrotricha" - New World Encyclopedia
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| − | '''Gastrotricha''' is a [[phylum]] of [[microscope|microscopic]], free-living, aquatic [[worm]]s, characterized by [[Symmetry (biology)#bilateral symmetry|bilateral symmetry]] and an acoelomate body plan. These animals, which are mostly less than 3 millimeters in length, are found in both [[freshwater]] and marine [[ecosystem]]s. They often have very high population densities. In marine sediments, they rank third in abundance and in freshwater ecosystems (as part of [[periphyton]], [[benthos]], and [[plankton]]), they rank among the top five most abundant groups (Todaro 2006). | + | '''Gastrotricha''' is a [[phylum]] of [[microscope|microscopic]], free-living, aquatic [[worm]]s, characterized by [[Symmetry (biology)#bilateral symmetry|bilateral symmetry]] and an acoelomate body plan. These animals, which are mostly less than 3 millimeters in length, are found in both [[freshwater]] and marine [[ecosystem]]s. They often have very high population densities. In marine sediments, they rank third in abundance and in freshwater ecosystems (as part of [[periphyton]], [[benthos]], and [[plankton]]), they rank among the top five most abundant groups (Todaro 2006). There are about 750 species, arranged into two orders, Chaetonotida and Macrodasyida (Todaro 2006). |
Revision as of 23:01, 5 June 2008
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 Darkfield photograph of a gastrotrich.
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Gastrotricha is a phylum of microscopic, free-living, aquatic worms, characterized by bilateral symmetry and an acoelomate body plan. These animals, which are mostly less than 3 millimeters in length, are found in both freshwater and marine ecosystems. They often have very high population densities. In marine sediments, they rank third in abundance and in freshwater ecosystems (as part of periphyton, benthos, and plankton), they rank among the top five most abundant groups (Todaro 2006). There are about 750 species, arranged into two orders, Chaetonotida and Macrodasyida (Todaro 2006).
Description
Gastrotrichs (from Greek gaster "stomach" and thrix "hair") are microscopic in size, ranging from 0.06 millimeters to 3 or 4 millimeters in length (Todaro 2006; Ramel 2008). They are bilaterally symmetric, with a complete gut.
a phylum of microscopic (0.06-3.0 mm) animals abundant in fresh water and marine environments. Most fresh water species are part of the periphyton and benthos. Marine species are found mostly interstitially in between sediment particles. They are bilaterally symmetric, with a complete gut, and the body is covered with cilia, especially about the mouth and on the ventral surface. There are terminal projections with cement glands that serve in adhesion.
They demonstrate eutely, with development proceeding to a particular number of cells, and further growth coming only from an increase in cell size.
This is a double-gland system where one gland secretes the glue and another secretes a de-adhesive to sever the connection. Like many microscopic animals, their locomotion is primarily powered by hydrostatics, and they reproduce entirely by parthenogenesis. Originally they were thought to have a body cavity (pseudocoel), but this was an artifact created by preservation methods, and they are now known to be acoelomate. Their relationship to other phyla is unclear. Morphology suggests that they are close to the Gnathostomulida, the Rotifera, or the Nematoda. On the other hand genetic studies place them as close relatives of the Platyhelminthes, the Ecdysozoa or the Lophotrochozoa. About 700 species have been described. The average life span of a gastrotrich is very short - about three days.
Classification
See 88 for suborders, subfamilies, and subgenera
- Order Chaetonotida Remane, 1925
- Family Chaetonotidae Gosse, 1864
- Genus Arenotus Kisielewski, 1987
- Genus Aspidiophorus Voigt, 1903
- Genus Caudichthydium Schwank, 1990
- Genus Chaetonotus Ehrenberg, 1830
- Genus Diuronotus Todaro, Balsamo & Kristensen, 2005
- Genus Fluxiderma d'Hondt, 1974
- Genus Ichthydium Ehrenberg, 1830
- Genus Halichaetonotus Remane, 1936
- Genus Heterolepidoderma Remane, 1926
- Genus Lepidochaetus Kisielewski 1991
- Genus Lepidodermella Blake, 1933
- Genus Musellifer Hummon, 1969
- Genus Polymerurus Remane, 1926
- Genus Rhomballichthys Schwank, 1990
- Genus Undula Kisielewski 1991
- Family Dasydytidae Daday,1905
- Genus Anacanthoderma Marcolongo, 1910
- Genus Chitonodytes Remane, 1936
- Genus Dasydytes Gosse, 1851
- Genus Haltidytes Remane 1936
- Genus Ornamentula Kisielewski 1991
- Genus Setopus Grünspan, 1908
- Genus Stylochaeta Hlava, 1905
- Family Dichaeturidae Remane, 1927
- Genus Dichaetura Lauterborn, 1913
- Family Neodasyidae Remane, 1929
- Genus Neodasys Remane, 1927
- Family Neogosseidae Remane, 1927
- Genus Neogossea Remane, 1927
- Genus Kijanebalola Beauchamp, 1932
- Family Proichthydidae Remane, 1927
- Genus Proichthydium Cordero, 1918
- Genus Proichthydioides Sudzuki, 1971
- Family Xenotrichulidae Remane, 1927
- Genus Draculiciteria Hummon, 1974
- Genus Heteroxenotrichula Wilke, 1954
- Genus Xenotrichula Remane, 1927
- Family Chaetonotidae Gosse, 1864
- Order Macrodasyida Remane, 1925
- Family Dactylopdolidae Strand, 1929
- Genus Dactylopodola Strand, 1929
- Genus Dendrodasys Wilke, 1954
- Genus Dendropodola Hummon, Todaro & Tongiorgi, 1992
- Family Lepidodasyidae Remane, 1927
- Genus Cephalodasys Remane, 1926
- Genus Dolichodasys Gagne, 1977
- Genus Lepidodasys Remane, 1926
- Genus Megadasys Schmidt, 1974
- Genus Mesodasys Remane, 1951
- Genus Paradasys Remane, 1934
- Genus Pleurodasys Remane, 1927
- Family Macrodasyidae Remane, 1926
- Genus Macrodasys Remane, 1924
- Genus Urodasys Remane, 1926
- Family Planodasyidae Rao & Clausen, 1970
- Genus Crasiella Clausen, 1968
- Genus Planodasys Rao & Clausen, 1970
- Family Thaumastodermatidae Remane, 1927
- Genus Acanthodasys Remane, 1927
- Genus Diplodasys Remane, 1927
- Genus Hemidasys Claparède, 1867
- Genus Platydasys Remane, 1927
- Genus Pseudostomella Swedmark, 1956
- Genus Ptychostomella Remane, 1926
- Genus Tetranchyroderma Remane, 1926
- Genus Thaumastoderma Remane, 1926
- Family Turbanellidae Remane, 1927
- Genus Desmodasys Clausen, 1965
- Genus Dinodasys Remane, 1927
- Genus Paraturbanella Remane, 1927
- Genus Prostobuccantia Evans & Hummon, 1991
- Genus Pseudoturbanella d'Hondt, 1968
- Genus Turbanella Schultze, 1853
- Family Xenodasyidae Todaro, Guidi, Leasi & Tongiorgi, 2006
- Genus Chordodasiopsis Todaro, Guidi, Leasi & Tongiorgi, 2006
- Genus Xenodasys Swedmark, 1967
- Incertae Sedis
- Genus Marinellina Ruttner-Kolisko, 1955
- Genus Redudasys Kisielewski, 1987
- Family Dactylopdolidae Strand, 1929
ReferencesISBN links support NWE through referral fees
- Integrated Taxonomic Information System (ITIS). 2006a. Gastrotricha Metschnikoff, 1865 ITIS Taxonomic Serial No.: 57597. Retrieved June 5, 2008.
- Integrated Taxonomic Information System (ITIS). 2006b. Chaetonotida Remane, 1924 ITIS Taxonomic Serial No.: 57822. Retrieved June 5, 2008.
- Integrated Taxonomic Information System (ITIS). 2006c. Macrodasyida Remane, 1924 ITIS Taxonomic Serial No.: 57598. Retrieved June 5, 2008.
- Ramel, G. 2008. The Phylum Gastrotricha. Earth-Life Web Productions. Retrieved June 5, 2008.
- Todaro, M. A. 2006. Gastrotricha: Overview]. University of Modena and Reggio Emilia. Retrieved June 5, 2008.
- Todaro, M. A. 2008. Gastrotricha: Systematics. University of Modena and Reggio Emilia. Retrieved June 5, 2008.
External links
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