The mode of asexual reproduction varies among different groups of organisms. In protists and monerans, the organism or the parent cell divides into two, to give rise to a new individual. Thus in these organisms, cell division is itself a mode of reproduction.
Various modes of asexual reproduction are
1. Fission It is the type of division of the parent body into two or more daughter individuals.
It can occur by following types
(i) Binary fission It is the type of fission in which parent body divides into two small, nearly equal sized daughter individuals. Eachgrows into an adult individual, e.g. Amoeba, Paramecium, etc.
Binary fission is of following types
(a) Simple binary fission, e.g. Amoeba.
(b) Longitudinal binary fission, e.g. Euglena, Vorticella.
(c) Transverse binary fission e.g. Paramecium, diatoms.
(d) Oblique binary fission, e.g. Ceratium, Gonyaulax.
(ii) Multiple fission It is the type of fission in which parent body divides into many small daughter individuals simultaneously,
e.g. Plasmodium (the malarial parasite), Amoeba (during unfavourable conditions).
2. Budding It is the mode of formation of a daughter individual from an outgrowth or bud that develops on the parent body.
Depending on the place where the bud develops, budding can be of two types
(i) External budding, e.g. Hydra
(ii) Internal budding (gemmule formation), e.g. Spongilla
3. Sporulation It occurs by tiny, single-celled, thin-walled spores that are extremely resistant to environmental stress. The spores form new individuals and are most commonly formed in Monera, Protista, Fungi and Algae.
Spores formed can be of following main types
(i) Zoospores, e.g. Chlamydomonas, Ulothrix.
(ii) Conidia, e.g. Penicillium, Aspergillus.
4. Fragmentation It is a mode of asexual reproduction in which parental body breaks into distinct pieces, each of which regenerates into an offspring. It is found in sponges, sea anemone (coelenterates) and echinoderms. It is also found in algae (e.g. Spirogyra), fungi, etc.
