Oscillatoria

CLASSIFICATION OF OSCILLATORIA

Sub-division :- Algae

Class :- Myxophyceae

Order :-  Oscillatoriales

Family :- Oscillatoriaceae

Genus :- Oscillatoria

One can hardly miss Oscillatoria when on a collection trip. It is almost cosmopolitan and occurs abundantly on moist rocks, cliffs, damp soil, muddy banks of streams, ponds, surface of the water reservoirs, sewage ponds, etc. A few species are marine and float on the surface.

STRUCTURE OF A FILAMENT AND SINGLE CELL

• Filaments occur either singly or interwoven to form a flat or spongy, free swimming mat.
• Filament consists of an inconspicuous and barely recognizable sheath enclosing unbranched trichome.
• Trichome consists of a single row of cells.
• The apical cell of the trichome may have calyptra-thick wall on its outer free face.
• The cells show typical myxophycean cell structure. It has no definite nucleus, no chloroplasts or no membrane bound organelles (prokaryotic cell).
• The cell shows many shining cyanophycean granules.
• Floating species show numerous gas vacuoles.

REPRODUCTIVE STRUCTURES

• The only method of reproduction is hormogone formation.
• The hormogones (small pieces of trichome with one to many uniform cells) are formed as a result of the death of intecalary cell or by the formation of special biconcave separation discs.
• Hormogones are liberated by the disintegration of discs.
• Each hormogone develops into a new filament.

IDENTIFICATION OF OSCILLAtORIA​

• Sub-division – Algae
  1. Thallus simple,
  2. Chlorophyll present.
  3. Cell walls of cellulose.
• Class – Myxophyceae
  1. Chromatophore not organised, pigments diffused, blue-green.
  2. Photosynthetic reserve cyanophycean starch.
  3. True nucleus absent.
  4. Sexual reproduction absent.
• Order – Nostocales
  1. Thallus with trichomes, unbranched, or with false branching.
  2. Hormogones, heterocysts, exospores and endospores generally present.
• Family – Oscillatoriaceae
  1. Trichomes uniseriate, sometimes tapering at the ends.
  2. Heterocysts and spores absent
  3. Sheath absent or diffluent.
• Genus– Oscillatoria
  1. Trichomes not in bundles.
  2. Trichomes without a sheath.
  3. Trichomes straight and cylindrical.