Important Characteristic Features of Cyanobacteria
The following special characteristics are found in these bacteria:
1. They show great diversity in form and shape. Some are spherical; some are rod-shaped, while few of them are unicellular or multicellular.
2. Vacuoles are formed in these bacteria.
3. Some forms are covered with sheath.
4. Unicellular forms are non-motile but trichome forms have capability of gliding movement.
5. Flagella are absent.
6. They are found in soil, clean water, and marine environment.
7. Some forms can live symbolically.
8. Some have the capacity to fix atmospheric nitrogen.
9. Some of them live symbolically with protozoans and such forms of bacteria are called as Cyanellae and diis association is described as Syncyanoses.
10. Nucleus is incipient like prokaryotes and is devoid of nuclear membrane and other membrane.
11. They contain chlorophyll 'a' and not bacterio chlorophyll, 'a' absorbs red light. Along with chlorophyll, 'a’ water-insoluble caroterioids and water-soluble phycobilins are also present. These two are the main light absorbing pigments. In some forms of bacteria red phycobilin (phycoerythrin) is found which can absorb light of short wave length (470 to 600 /mm).
12. Cell division incorporates cytoplasmic division as well as cell plate formation.
13. Stored food is Cyanobacteria starch.
14. In trichomes of Cyanobacteria heterocysts are also present which help in fixation of free nitrogen. Cell wall is much thicker in comparison with the Qthei cells of the trichome.
15. In some forms thick-walled akinetes are also found which help them to survive in unfavorable conditions.
16. Like bacteria they also lack sexual reproduction.
Cyanobacteria or blue-green algae like other algae are able to prepare their own food through photosynthesis but they are different from photosynthetic bacteria, which do not produce oxygen ducing photosynthesis. Chlorophyll 'a' and biliprotein- are present in Cyanobacteria while in bacteria, bacterial chlorophyll is present.
Cyanobacteria or blue-green algae are present in large amount on land and water. They may-grow in such conditions in which other plants cannot grow. They may grow in acidic or plain waters, extreme cold and hot streams (50-60°C and up to 85°C), moist soil; salt-water lakes etc.
Along with other organisms, they are found as saprophyte and parasites. They form a thick mucilaginous covering on soil or rock surface. They are found in large numbers in damp places where moisture is more, e.g., slopes of the mountains, on rocks, on bark of trees etc. Mostly, they are found in rivers, lakes, ponds etc. They can move in water.