Short Notes on Algae
ALGAE Definition: Algae is a chlorophyll-bearing, simple, thalloid, autotrophic and largely aquatic organism
Habitats: Naturally occur in moist stones, soils and wood
occur in association with
fungi – lichen
animals – sloth bear
Form and size – highly variable
Reproduction
- Vegetative reproduction – fragmentation.
- Asexual reproduction – different types of spores, common – zoospores
- Sexual reproduction – fusion of two gametes.
FORM AND SIZE
- unicellular – Chlamydomonas
- colonial form – Volvox
- filamentous – Ulothrix and Spirogyra.
- massive plant bodies – kelps
TYPE OF GAMETE
- isogamous flagellated and similar in size
- non-flagellated and similar in size – Spirogyra
- anisogamous
- gametes dissimilar in size
- oogamous – Volvox, Fucus
USEFUL TO MANKIND
- half of the total carbon dioxide fixation on earth is carried by algae
- increase the level of dissolved oxygen in their immediate environment
- paramount importance as primary producers of energy-rich compounds
- Porphyra, Laminaria and Sargassum and 70 species of marine algae are used as food.
- algin (brown algae) and carrageen (red algae) produce large amounts of hydrocolloids
- Gelidium and Gracilaria are used to grow microbes and in preparations of ice-creams and jellies
- Chlorella rich in proteins is used as food supplement even by space travellers