Planaria

Planaria is a genus of planarians in the family Planariidae. When an individual is cut into pieces, each piece has the ability to regenerate into a fully formed individual.[1]

The two darkest areas on the "head" end of this planaria are primitive eye-spots (photomicrograph at 40x magnification)
For the common name given to many non-parasitic flatworms, see Planarian.

Planaria
Planaria torva
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Platyhelminthes
Order: Tricladida
Family: Planariidae
Genus: Planaria
OF Müller, 1776

Description

Currently the genus Planaria is defined as freshwater triclads with oviducts that unite to form a common oviduct without embracing the bursa copulatrix and with an adenodactyl present in the male atrium. The testes occur along the whole body.[2]

Planaria originally have habitats in dark, murky water which results in such sensitivity (Paskin et al., 2014). They are also sensitive to other stimuli such as chemical gradients, vibration, magnetic and electric fields (Deochand et al., 2018). Their central nervous system includes the anterior (head, brain and eyes) and middle (abdominal trunk and pharynx) (Deochand et al., 2018).

Diet

The food of Planaria species includes freshwater gastropods, tubificid worms, and freshwater arthropods, such as isopods of the genus Asellus and chironomid larvae.[3] In the United Kingdom, P. torva is a successful predator of the invasive New Zealand mud snail (Potamopyrgus jenkinsi).[4]

Species

The following species are recognised in the genus Planaria:

  • Planaria adhaerens Korotneff, 1909
  • Planaria albocingata Korotneff, 1912
  • Planaria barroisi Whitehouse, 1914
  • Planaria bicingulata Korotneff, 1912
  • Planaria chulunginensis Sabussow, 1903
  • Planaria cincinata Korotneff, 1912
  • Planaria cinerea Stimpson, 1857
  • Planaria dagarensis Sabussow, 1903
  • Planaria debilis Korotneff, 1912
  • Planaria delineata Korotneff, 1912
  • Planaria dybouskyi Sabussow, 1903
  • Planaria flava Delle Chiaje, 1822
  • Planaria fontana Schrank, 1803
  • Planaria fuliginosa Leidy, 1851
  • Planaria fuliginosus Leidy, 1851
  • Planaria fulvifrons Grube, 1872
  • Planaria fuscomaculata Korotneff, 1912
  • Planaria gigas Leuckart, 1828
  • Planaria grubii Sabussow, 1903
  • Planaria ignorata Raspail, 1902
  • Planaria incerta Korotneff, 1912
  • Planaria kempi Whitehouse, 1913
  • Planaria lemani (du Plessis, 1874) Graff, 1876
  • Planaria lucta Korotneff, 1912
  • Planaria luteola Delle Chiaje, 1822
  • Planaria macrocephala Fries, 1879
  • Planaria maculata Dalyell, 1853
  • Planaria marmorosa Müller, 1776
  • Planaria melanocerca Korotneff, 1912
  • Planaria melanopunctata Korotneff, 1912
  • Planaria melanotorquis Korotneff, 1912
  • Planaria nesidensis Delle Chiaje, 1822
  • Planaria onegensis Sabussow, 1903
  • Planaria punctatum Carus, 1863
  • Planaria rosea Müller OF, 1773
  • Planaria rothii Braun, 1884
  • Planaria sabussowi Korotneff, 1912
  • Planaria savignyi Leuckart, 1828
  • Planaria semifasciata Korotneff, 1912
  • Planaria simplex Woodworth, 1896
  • Planaria sinensis Stimpson, 1857
  • Planaria subflava Korotneff, 1912
  • Planaria torva (Müller OF, 1773)
  • Planaria tremellaris Grube, 1840
  • Planaria unionicola Woodworth, 1897
  • Planaria verrucosa Delle Chiaje, 1829
  • Planaria wytegrensis Sabussow, 1907
  • Planaria zeylanica Kelaart, 1858

Uses of planaria in research

Planaria has been widely used as a model invertebrate organism in pharmacological research, in particular in the studies of the drugs of abuse.[5] Due to its excellent ability to regenerate, planaria has also been used as a model in regeneration studies.[6] It was also proposed as a model in toxicological research.[7]

References
Wikispecies has information related to Planaria.
  1. "Unravelling How Planaria Regenerate". Sedeer el-Showk. Retrieved 26 January 2017.
  2. Ball, Ian R.; Reynoldson, T. B.; Warwick, T. (2009). "The taxonomy, habitat and distribution of the freshwater triclad Planaria torva (Platyhelminthes: Turbellaria) in Britain". Journal of Zoology. 157 (1): 99–123. doi:10.1111/j.1469-7998.1969.tb01691.x. ISSN 0952-8369.
  3. Reynoldson, T. B.; Sefton, A. D. (1976). "The food of Planaria torva (Müller) (Turbellaria-Tricladida), a laboratory and field study". Freshwater Biology. 6 (4): 383–393. doi:10.1111/j.1365-2427.1976.tb01623.x. ISSN 0046-5070.
  4. Reynoldson, T. B.; Piearce, Bronwen (1979). "Predation on snails by three species of triclad and its bearing on the distribution of Planaria torva in Britain". Journal of Zoology. 189 (4): 459–484. doi:10.1111/j.1469-7998.1979.tb03974.x. ISSN 0952-8369.
  5. Raffa, Robert B. (3 December 2008). Planaria: A Model for Drug Action and Abuse. CRC Press. doi:10.1201/9781498713597. ISBN 978-0-429-08997-8.
  6. "Model systems for regeneration: planarians". journals.biologists.com. doi:10.1242/dev.167684. Retrieved 21 January 2023.
  7. Shah, Syed Ibrahim; Williams, Adrian C.; Lau, Wing Man; Khutoryanskiy, Vitaliy V. (1 December 2020). "Planarian toxicity fluorescent assay: A rapid and cheap pre-screening tool for potential skin irritants". Toxicology in Vitro. 69: 105004. doi:10.1016/j.tiv.2020.105004. ISSN 0887-2333. PMID 33010358. S2CID 222159871.


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