Spirogyra

Spirogyra
Spirogyra with its characteristic helicallly arranged chloroplasts.
Scientific classification
Domain:	Eukaryote
(unranked):	Archaeplastida
Kingdom:	Plantae
Division:	Chlorophyta
(unranked):	Streptophyta
Class:	Zygnematophyceae
Order:	Zygnematales
Family:	Zygnemataceae
Genus:	Spirogyra Link in C. G. Nees, 1820
Type species
Spirogyra porticalis (O.F.Müller) Dumortier
Species
Over 400; see text.

Spirogyra (common names include water silk, mermaid's tressses, and blanket weed) is a genus of filamentous charophyte green algae of the order Zygnematales, named for the helical or spiral arrangement of the chloroplasts that is diagnostic of the genus. It is commonly found in freshwater areas, and there are more than 400 species of Spirogyra in the world.^[1] Spirogyra measures approximately 10 to 100 μm in width and may grow to several centimeters in length.

General characteristics

Spirogyra is very common in relatively clean eutrophic water, developing slimy filamentous green masses. In spring Spirogyra grows under water, but when there is enough sunlight and warmth they produce large amounts of oxygen, adhering as bubbles between the tangled filaments. The filamentous masses come to the surface and become visible as slimy green mats. Mougeotia and Zygnema are often found tangled together.

Reproduction

Spirogyra can reproduce both sexually and asexually. In vegetative reproduction, fragmentation takes place, and Spirogyra simply undergoes the intercalary mitosis to form new filaments.

Sexual Reproduction is of two types:

1. Scalariform conjugation requires association of two 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.
2. 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.

Species

The following species are currently accepted:^[2]

Gallery

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  Spirogyra

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  Spirogyra

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  Single Spirogyra cell

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  Spirogyra (Each numbered tick = 122 µM)

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  Spirogyra (Each numbered tick = 20 µM)

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  Patch of Spirogyra from algal blooming in Westfalian pond

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  Spirogyra algal bloom in Romanian pond

References

Wikimedia Commons has media related to Spirogyra.

• Spirogyra at microscopy-uk.org.uk
• John Whitton, B.A. and Brook, A.J. (editors) 2002. The Freshwater Algal Flora of the British Isles. Cambridge University Press, Cambridge. ISBN 0-521-77051-3.