Spirogyra (common names include water silk, mermaid's tresses, and blanket weed) is a genus of filamentous charophytegreen algae of the orderZygnematales, named for the helical or spiral arrangement of the chloroplasts that is characteristic of the genus. Spirogyra species, of which there are more than 500, are commonly found in freshwater habitats.[3]Spirogyra measures approximately 10 to 150 micrometres in width (though not usually more that 60) and may grow to several centimetres in length.[4][5][6]
Distribution
Spirogyra can be been found on every continent on Earth, including Antarctica. It is freshwater algae, found rivers, ponds, and other such bodies of water.[7]
Taxonomy
The genus Spirogyra was named by German naturalist Johann Heinrich Friedrich Link in 1820. The lectotype, Spirogyraporticalis was designated in 1952 by Paul C. Silvia.[8]
Reproduction
The freshwater alga Spirogyra
Spirogyra can reproduce both sexually and asexually.[9] In vegetative reproduction, fragmentation takes place, and Spirogyra simply undergoes intercalarycell division to extend the length of the new filaments.[10]
Sexual reproduction is of two types:
Scalariform conjugation requires association of two or more different filaments lined side by side, either partially or throughout their length. One cell each from opposite lined filaments emits tubular protuberances known as conjugation tubes, which elongate and fuse to make a passage called the conjugation canal. The cytoplasm of the cell acting as the male travels through this tube and fuses with the female cytoplasm, and the gametes fuse to form a zygospore.
In lateral conjugation, gametes are formed in a single filament. Two adjoining cells near the common transverse wall give out protuberances known as conjugation tubes, which further form the conjugation canal upon contact. The male cytoplasm migrates through the conjugation canal, fusing with the female. The rest of the process proceeds as in scalariform conjugation.
The essential difference is that scalariform conjugation occurs between two filaments and lateral conjugation occurs between two adjacent cells on the same filament.
Usage
Spirogyra species are being researched for their potential in bioremediation. Specifically, in stemming toxic runoff from mines (where they are often found occurring naturally)[11] and from municipal wastewater.[12] Spirogyra has also been investigated as a potential biofuel.[12]
Spirogyra species, such as S. varians, are also being researched for potential pharmaceutical usage due to their high nutrient densities.[13]
Species
The following species are currently accepted. For a more comprehensive and up-to-date list of currently excepted species, view the pages on AlgaeBase or WoRMS.
^ abGe, Shijian; Madill, Max; Champagne, Pascale (April 2018). "Use of freshwater macroalgae Spirogyra sp. for the treatment of municipal wastewaters and biomass production for biofuel applications". Biomass and Bioenergy. 111: 213. Bibcode:2018BmBe..111..213G. doi:10.1016/j.biombioe.2017.03.014.
John Whitton, B.A. and Brook, A.J. (editors) 2002. The Freshwater Algal Flora of the British Isles. Cambridge University Press, Cambridge. ISBN0-521-77051-3.
