There are three groups of algae:
1.CHLOROPHYTA –Green algae
2. PHAEOPHYTA- Brown algae
3.RHODOPHYTA—Red algae
Red algae is known as advanced algae and Green algae as a primitive one.
Characteristics of Algae
•1.They are planktons( on the water surface) Benthos ( Organisms grow attached to the bottom of water reservoir) Epipellic ( grow attached to mud) Epilithic( Grow attached to the rocks & stones) Thermophytes ( Grow at a very high temperature 70-85˚C )
•Cryophytes : Algae grow in polar region on ice or snow Ex. Haematococcus causes red snow ball in alpine region due to haematochrome.
•Like wise Chlamydomanas nivalis develop red coloured haematochrome in the cell wall of akinetes & causes red snow.
Epihytes (That grow on the surface of other plant parts)
Endophytes ( that grow inside the tissue of plants)
•Epizoophytes ( that grow on bodies of the animal) Endozoophytes ( That grow in the bodies of animals)
•Symbiotic algae: Lichen ( algae with fungi)
•Parasitic algae: Green algae Cephaleuros virescens causes red rust on tea leaves and Cephaleuros coffeae causes red rust on coffee leaves.
2.Thalloid body that is not differentiated into root stem and leaves. Multicellular forms may be palmelloid ( colony of cell with indefinite shape and number of cell) Coenobial (colony of cell with definite shape and number of cells) Dendroid (colonial tree) Coenocytic thallus and Filamentous type.
3.Chloroplast present there may be single chloroplast or more than one in single cell.
4. Flagellum is present in most of the cases it is of two types tinsel shape & whiplash type.
5. Vegetative reproduction by fragmentation budding hormogonia and by propagules.
6. Asexual reproduction by spores.
7. Sexual reproduction may be isogamous anisogamous or oogamous. Sex organs are uni or multicellular without sterile jacket.
IMPORTANT POINTS
| GREEN ALGAE | BROWN ALGAR | RED ALGAE |
| CHLOROPHYLL a & b | CHLOROPHYLL a & c , Fucoxanthin | CHLOROPHYLL a & d Phycoerythrins |
| Reserve food material is STARCH | MANITOL ,LAMINARIN | FLORIDEAN STARCH |
| Flagella present | present | absent |
•#Unicellular green algae Ex. Chlorella used to provide oxygen during space flights.
•#Alginic acid is obtained from giant brown algae or kelps in India from Sargassum it yields alginate which used as emulsifier ,thickner or to stop bleeding.
•#Agar is obtained from Gelidium ,Chondrus etc. used in jellies creams bakery leather and textile industries act as laxative.
•# Carrageenin is obtained from Chondrus Used in food industry and as blood coagulant.
•#Extract of Corallina is used for kidney treatment.