The two division of algae contain prokaryotic algae which are now usually called bacteria in view of their cell structure being very similar to eubacteria. Thus cyanophyta are called cyanobacteria and prochlorophyte are termed Prochlorobacteria.
Blue-green algae are found in all parts of the world from the tropics to the polar regions, and form the oceans to the top of the mountains. Majority of genera are found both in fresh as well as in saltish water.
General Characters Of Cyanobacteria
- They have a prokaryotic cell organization.
- They lack the membrane bound cell organelles such as chloroplast, mitochondria, E.R., nucleus. They lack definite chromosome however DNA fibrils are present.
- Photosynthetic pigment include chlorophyll a, beta – carotene, xanthophylls and biliproteins generally scattered in the peripheral protoplasm.
- Thallus bears a specialized gliding movement.
- Reserve food material is cyanophycean starch and cyanophycean granules.
- The cytoplasm of cell is divided into two parts the outer or peripheral chromoplasm and the central colorless centroplasm.
- Many members of class cyanophyta are involved in nitrogen fixation.
- All the members of this class s create mucilage and usually possesss a mucilage sheath. This muciliage may be yellow, brown, red or purple in color.
- Many floating and planktonic algae member of this class bears gas vacuole.
- Vegetative reproduction is by means of hormone is, endospore, and nano types like structure.
- No sexual reproduction is reported.
- No motile cells (even the reproductive cells are non motile) and lack flagella.