Lee Kong Chian Natural History Museum

Cosmarium sp. Corda, 1834

Kingdom:Plantae
Phylum/Division:Chlorophyta
Class:Zygnematophyceae
Order:Zygnematales
Family:Desmidiaceae
Genus:Cosmarium
Common Names:Desmids
Status:Common

Description

Generally unicellular, the cells are compressed with the length slightly greater than the breadth and a distinct median constriction, some have their cells joined into long filaments. The cell wall is smooth or variously ornamented. The front view of the semicells may be semicircular, elliptic, reniform, trapezoidal or subquadrate. The vertical view is usually elliptical in outline and often with lateral elevations midway between the poles. Each semicell has a single axial chlorpolast with four radiating plates and the pyrenoids are found in the axial portion.

Read more about the Zygnematales order.
Read more about the Desmidiaceae family.

Localities

Most freshwaters.

Locality Map

General Biology

A common unicellular green algas in freshwater, Cosmarium are attractive in their symmetry and shapes as well as diversity in ornamentation. They are free-floating and intermingled with other algae.

Life Cycle

Conjugation takes place when two cells come together, each surrounded by a common gelatinous sheath. The cells breaks at the isthmus and the cell contents fuse to form a zygote midway between the conjugating cells. The zygote divides into two cells.

References

Bold, H. C., C. J. Alexopoulos & T. Delevoryas, 1987. Morphology of plants and fungi. Harper & Row, New York. (5th ed.). 912pp.

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