Planaria

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

Planaria is a genus of planarians in the family Planariidae. Due to its excellent ability to regenerate, species of Planaria has also been used as model organisms in regeneration studies.^[1] When an individual is cut into pieces, each piece has the ability to regenerate into a fully formed individual.^[2] When decapitated, they retain their memories.^[3]

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.^[4]

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.^[5] In the United Kingdom, P. torva is a successful predator of the invasive New Zealand mud snail (Potamopyrgus jenkinsi).^[6]

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

Application of planaria in research

These invertebrates are valuable models in toxicology, neuroscience, and pharmacology, offering ethical and cost-effective alternatives to vertebrate testing. Planaria’s simple nervous system, high sensitivity to environmental changes, and well-characterized genome make them particularly useful for studying chemical toxicity, wound healing, and neuroregeneration. Their ease of maintenance in laboratory settings further enhances their appeal for research. In pharmacology and neuroscience, planaria provide a unique opportunity to study the effects of psychoactive compounds, including investigations into drug addiction and withdrawal responses^[7]. In drug delivery studies, they can be used to assess the biocompatibility and potential irritancy of pharmaceutical formulations, providing insight into their effects on biological tissues^[8]. Additionally, their remarkable ability to regenerate lost body parts makes them an important model for stem cell research, offering insights into cellular and molecular mechanisms of regeneration.

References

^ Mario Ivankovic; Radmila Haneckova; Albert Thommen; Markus A. Grohme; Miquel Vila-Farré; Steffen Werner; Jochen C. Rink (2019). "Model systems for regeneration: planarians". Development. 146 (17). doi:10.1242/dev.167684. Retrieved 21 January 2023.
^ "Unravelling How Planaria Regenerate". Sedeer el-Showk. Retrieved 26 January 2017.
^ Rowan Jacobsen (1 February 2024). "Brains Are Not Required When It Comes to Thinking and Solving Problems—Simple Cells Can Do It". Scientific American.
^ 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.
^ 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.
^ 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.
^ 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.
^ 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.

Deochand, N., Costello, M. S., & Deochand, M. E. (2018). Behavioral Research with Planaria. Perspectives on behavior science, 41(2), 447–464. https://doi.org/10.1007/s40614-018-00176-w

This flatworm-related article is a stub. You can help Wikipedia by expanding it.

[1] Mario Ivankovic; Radmila Haneckova; Albert Thommen; Markus A. Grohme; Miquel Vila-Farré; Steffen Werner; Jochen C. Rink (2019). "Model systems for regeneration: planarians". Development. 146 (17). doi:10.1242/dev.167684. Retrieved 21 January 2023.

[2] "Unravelling How Planaria Regenerate". Sedeer el-Showk. Retrieved 26 January 2017.

[3] Rowan Jacobsen (1 February 2024). "Brains Are Not Required When It Comes to Thinking and Solving Problems—Simple Cells Can Do It". Scientific American.

[Ball2009-4] 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.

[ReynoldsonSefton1976-5] 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.

[Reynoldson1979-6] 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.

[:0-7] 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.

[8] 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.

[1]

[2]

[3]

[4]

[5]

[6]

[7]

[8]