Asexual Reproduction in Algae
- Reproduction in algae occurs by all the three methods
- Vegetative Reproduction
- Asexual Reproduction
- Sexual Reproduction
1) Vegetative Reproduction
- Vegetative methods of reproduction occurs through binary fission ( in unicellular forms), fragmentation ( in filamentous forms), or by formation of akinetes, hormogonia, tubers or by the formation of adventitious thalli.
2)Asexual Reproduction
- Asexual reproduction occurs by formation of different types of spores that are formed from the Vegetative thallus and do not involve meiosis.
- The different types of asexual spores are,
- Zoospores
- Aplanospores
- Synzoospores
- Hypnospores
- Autospores
- Palmella Stage
- Cysts
1.Zoospores
- These are motile, naked, flagellated reproductive units. They may be biflagellated ( Ulothrix, Chlamydomonas etc), quadiflagellated (Oedogonium) or multiflagellated with rings of paired flagella. Zoospores are produced by different number of divisions of the Vagetative cells.
2.Aplanospores
- These are nonmotile zoospores and do not possess flagella. They are produced in the same way like zoospores but under adverse condition especially in lack of water.
- 3.Synzoospores
- Multiflagellated multi nucleated zoospores are called as synzoospores.
- 4.Hypnospores
- These are thin walled aplanospores which overcome the adverse situation. It is formed from the entire content of the cell.
- 5.Autospores
- In some forms like Scenedesmus, the resting spores develop all the structures of the parent cell in which they are formed and are exactly similar to the parent cell except in size. These are called as autospores.
- 6.Palmella Stage
- Sometimes the cells of many algae continue to divide but their contents are not separated and liberated due to adverse environmental conditions. The mother cell wall becomes gelatinous forming a covering around the cells that look like colony of the cells and this is called palmella stage as it looks like Palmella, a genus. On return of favourable condition, the cells comes out as zoospores or aplanospores to germinate.
- 7.Cysts
- Cysts are thick walled spores like structures formed by thickening of the walls of each portion of the cell that divides under adverse condition into chambers. Sometimes, cysts may be formed out of rhizoids – called as rhizocysts. Under favourable condition, they germinate to Vegetative thallus.
