(i) Budding:
It is the process of formation of an offspring from an outgrowth or bud of a parent. The bud may be unicellular or multi-cellular depending upon the nature of the parent individual.
In coelenterates, tunicates and other multi-cellular animals it consists of a small number of cells surrounded by an epithelium.
In hydra it is usually formed in the lower half of the body. The buds separate from the parent soon after their formation after some initial growth.
In many cases individuals developed from them do not separate but remain interconnected to form a colony.
(ii) Spore formation:
ADVERTISEMENTS:
A majority of fungi and bacteria asexually reproduce by speculation. In fungus, a sporangium develops from the fungal hyphen. The nucleus divides several times within the sporangium. Each nucleus gets surrounded by a bit of cytoplasm to form spore.
On maturation of sporangium (formation of spores), the sporangium ruptures to liberate a large number of minute spores. The spores develop into new hyphen after reaching suitable substratum.
(iii) Regeneration:
The ability of an organism to replace its lost body parts is called regeneration. Hydra, planarian and sponges exhibit regeneration. In hydra, 1/6 mm body piece is capable of regenerating into an entire individual.
(iv) Fragmentation:
The mature spirogyra (algae) breaks into two or more pieces (fragments). Each fragment grows into new individual. The process is called fragmentation.