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Chroococcus – A Brief (Case Study) on the Living Way of Chroococcus

Chroococcus – We will Learn Systematic Position, Plant Body, Cell Structure, Reproduction

Chroococcus (Gr. chroo, color. coccus, berry) are, predominantly fresh water alga. It is found in damp places such as moist soil, tree trunks, moist walls and rocks. This genus is represented by 250 species. They are either free floating or form a thin layer on soil.

There are many marine and brackish species (with salinity less than in the marine environment; generally, less than two percent). They often form blooms especially during warm months of the year. The cells are single or united into spherical colonies, each containing a small number of cells. Some common species are C. limneticus, C. turgidus.

Chroococcus-algae
Chroococcus Algae: Microscopic view

Systematic Position

  • Class: Cyanophyceae
  • Order: Chroococales
  • Family: Chroococcaceae
  • Genus: Chroococcus

Plant Body

The genus Chroococcus consists of many algae species which many have rounded or spherical cells. Some species may contain solitary cells but mostly families of 4 to 16 individual cells are found. Each cell of the colony is independent and is enveloped in a gelatinous mass.

Cell Structure

Each cell is tiny rounded or spherical body. The cell wall consists of an inner thin cellular layer a medium pectic layer and an outer mucilage layer. The cytoplasm occurs as chromoplasm (peripheral) and as a central body (centroplasm). Nucleus is not organized with nuclear membrane and nucleolus. There are no true vacuoles but pseudo vacuoles (packet of air) are present. The pigments are found in the chromoplasm (peripheral) part. Pigments found are chlorophyll a, phycocyanin-r, phycocyanin-c, phycoerytherin-c, β-carotene and as many as eight Xanthophylls. Reserve food material is a glycogen like substance along with some oil drops. Mitochondria, endoplasmic reticulum and Golgi bodies are also absent.

chroococcus-sp
Chroococcus sp: A, vegetative phase. B, dividing phase. C, single cell showing gas vacuole or pseudovacuoles

Reproduction

  1. The reproduction takes place by cell fission only.
  2. The newly formed cells do not separate immediately, but remain held together in mucilaginous covering forming non filamentous colonies of 2-4 cells.
  3. A cell may divide in three different directions. Cells grow in size and become independent. Only in rare cases nannocytes have also been found.
  4. The characteristic feature of this class is the absence of Sexual reproduction and motile reproductive structures.
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