(a) Fragmentation: Multicellular organisms with simple body organisation such as filamentous algae-Spirogyra breaks up into two or more small pieces or fragments upon maturation. These fragments grow into new individuals.
Fragmentation in spirogyra
(b) Regeneration: It is the ability of a fully differentiated organism to give rise to new individual organisms from its body parts.
Small cut or broken parts of the organism body grow or regenerate into separate individuals.
Planaria can be cut into any number of pieces and each piece grows into a complete organism.
Regeneration is carried out by specialised cells which proliferate and make large number of cells thus, undergoing changes to become various cell types and tissues.
The changes taking place in an organised sequence is development.
