Hi dear students Today we will talk about The CYANOPHYCEAE | For more information, read the following list below.
THE CYANOPHYCEAE ARE EXPLAIN
The Cyanophyceae or the blue green algae constitute a primitive group of plants havig simple prokaryotic structure. This group of algae comprises about comprises about 1500 species unde 150 genera. They occur widely in water, in all possible habitats. About 22 filamentous species of blue-green algae are known to fix atmospheric nitrogen, thus adding to the fertility of the rice fields especially in the tropical countries. Species of Anabaena, Aulosira, Nostoc, Tolypothrix Mastigocladus, Calothris, etc are known to fix nitrogen due to the presence of heterocysts certain species that are devoid of heterocyst, are also able to fix atmospheric nitrogen undar anaerobic conditions (Plectonema boryanum).
Characteristic features of Cyanophyceae:
1. Vegetative body is either unicellular, multicellular colonial or multicellular filamentos
2. Cells are prokaryotic. 3.Photosynthetic pigments are chlorophyll-a
carotenoids myxoxanthin and mypxaranthophohyll, the blue pigment c-phycocyanin and the red pigment c-phycoerytbring .
4.Pigments are distributed throughout the entire peripheral portion of the protoplast of the celled chromoplasm,
5. Absence of food material is cyanophycean starch, cyanophycin and a carbohydan trehalose.
6. Absence of motile cells and reproductive structures.
7. Total absence of sexual reproduction
8. Some blue green algae possess a specialised structure known as beterogsts, that help fixation of atmospheric nitrogen.
The member of Cyanophyceae, commonly known as blue-green algae, are found in a wide variety of habitats, all over the world. Most are found in fresh water habitats in lakes streams, (Anabaena, Nostos, Rivnlaria), some are marine (Dermocarpus, Trcbodesmium) species of Nostor scytonema of Nasts, Scytonema remain attached to moist rocks in the form of mucilaginous clumps Many species of nostoc oscillataria are , terrestrial. Gloeocapsa alpine, Calothrixs parietina are found to colonise calcareous rocks. Blue-green algae growing in organically rich water of lakes,ponds form plankton. Blue-green algae are also found in hot springs having i having high temperatures. Eg Chrooorcus, Microgystis, Oscillatoria, Plectonema, Mastrgocladus, Phormidium etc. Phormidium, Microcoleus have been reported from snow. Various types of symbiotic.
The thallus ranges from unicellular to large branched heterotrichous forms. Chroococus,syechococcus are unicellular forms. Microcystis, Gloeocapsa are colonial forms. Oscillatoria is a simple unbranched flament, while Anabaena, Nostoc are unbranched filamentous members othr that possess heterocysts and akinetes. The thalli of Stigonema, Mastigocladus, are heterotrichous with true branches and possess heterocysts and akinetes. Scytonema and tolypothrix filaments exhibit false branching.