Majority of them are aquatic, marine ( Gracilaria, and Sargassum ) and freshwater ( Oedogonium, and Ulothrix ) and also found in soils ( Fritschiella, and Vaucheria ). Chlorella lead an endozoic life in hydra and sponges whereas Cladophora crispata grow on the shells of molluscs. Algae are adapted to thrive in harsh environment too. Dunaliella salina grows in salt pans ( Halophytic alga ).
Algae growing in snow are called Cryophytic algae . Chlamydomonas nivalis grow in snow covered mountains and impart red colour to the snow ( Red snow ). A few algae grow on the surface of aquatic plants and are called epiphytic algae ( Coleochaete, and Rhodymenia ). The study of algae is called algology or phycology .
Some of the eminent algologists include F.E. Fritsch, F.E. Round, R.E. Lee, M.O.Parthasarathy Iyengar, M.S.
Randhawa, Y. Bharadwaja, V.S. Sundaralingam and T.V.Desikachary. .
. General Characteristic features The algae show a great diversity in size, shape and structure. A wide range of thallus organisation is found in algae. Unicellular motile ( Chlamydomonas ), unicellular non-motile ( Chlorella ), Colonial motile ( Volvox ), Colonial non motile ( Hydrodictyon ), siphonous ( Vaucheria ), unbranched filamentous ( Spirogyra ), branched filamentous ( Cladophora ), discoid ( Coleochaete ) heterotrichous ( Fritschiella ), Foliaceous ( Ulva ) to giant kelps ( Laminaria and Macrocystis ).
The thallus organization in algae is given in Figure . . Algae are eukaryotes except blue green algae. The plant body does not show differentiation into tissue systems.
The cell wall of algae is made up of cellulose and hemicellulose. Siliceous walls are present in diatoms. In Chara the thallus is encrusted with calcium carbonate. Some algae possess algin, polysulphate esters of polysaccharides which are the sources for the alginate, agar agar and carrageenan.
The cell has a M.O.Parthasarathy ( - ) ‘Father of Indian Phycology’. He conducted research on structure, cytology, reproduction and taxonomy of Algae. He published a Monograph on Volvocales. New algal forms like Fritschiella, Ecballocystopsis, Charasiphon and Cylindrocapsopsis .
were reported by him. Figure . : Thallus organization in