Oscillatoria Structure and Reproduction

Oscillatoria

Taxonomic Position

Kingdom: Bacteria

Division: Cyanobacteria

Class: Cyanophyceae

Order: Oscillatoriales

Family: Oscillatoreaceae

Genus: Oscillatoria

Occurrence

It occurs in wide variety of habitat. It is common in fresh water, damp place, ditches, drains etc. it is also found as patches on the mud surface. It is most common in moist places where abundant organic matter is present. Patches of entangled masses of filaments are often found, floating on the surface of fresh water channels/

Microscopic View of Oscillatoria

Plant Body

Thallus

The thallus consists of free living trichome. It has distinct filamentus texture. The trichome consists of a single row of cells. The filament is unbranched and gelatinous sheet is very thin. The cells are cylindrical but broader than long. All the cells are similar in shape except the apical one, which is convex at the top. The septa are faintly visible and marked by row of granules.

Cell Structure

All the cells in trichome are similar in structure. The cells are without any mitochondria, endoplasmic reticulum and Golgi bodies.

Cell wall

Each cell has a well-developed cell wall. The cell wall is being stable and hardly any mucilaginous sheath external to it.

Pigments

Plastids are absent. The pigments are found in the flattened sac like structure called lamellae. The lamellae are not organized into grana. Cells are blue in color due to the presence of phycocyanine (a blue pigment), chlorophyll, carotene and phycoerythrin.

Nucleoplasm

A definite nucleus is absent and nuclear material is present as central body, which lacks nucleolus.

Reserve food material

Reserve food is in the form of sugars and glycogens and proteinaceous material cyanophycin.

Vacuole

Sometime the pseudo vacuoles are also present in the protoplast of certain species.

Movement

The characteristic of Oscillatoria is the slow rhythmic but active movement of the trichome. The movement is jerky pendulum like. This type of movement is termed as oscillatory movement.

Growth

The growth of the trichome is intercalary. The division is right angle to the longitudinal axis. This result in the increase in the length of trichome, which is never more than one cell wide. The cell divides by amitotically.

A-Oscillatoria B-Phormidium CF-Simplicissimum C-Planktothrix

Reproduction

Fragmentation

The filament breaks into two or more fragments. Each fragment grows to produce new plant body.

Oscillatoria reproduce vegetatively. The only method of reproduction is the formation of hormogones. The break takes place where a dead cell is situated.

Necridia

During the growing season, the cell in the trichome collapses. The protoplast is change into mucilage. The mucilage filled cells are called necridia. The dead cell loses its turgidity. The mutual pressure on the wall of adjacent cell released. They become convex so that the dead ceil appears biconcave. The cells are separated in the form of hormogones from the dead cells.

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