Morphallaxis - Regeneration

This kind of regeneration takes place in plants, sponges and coelenterates such as jelly fishes and hydra. The missing parts are replaced via reorganization or re-modelling of the pre-existing ones. The wound is healed and the re-neighboring tissues re-organize themselves into whatever parts might have been lost or removed. So in this type of regeneration the residual part of the animal is able of restoring the lost part or giving rise to the whole organism just by remodelling or reorganising the entire available mass of cells into a new whole. The process does not include growth until the lost part or the whole body is regenerated, which is necessarily small at first.

Growth to reach normal size occurs later. Morphallactic regeneration can occur in total absence of cell division, as is seen in the case of regeneration in Hydra. A part of Hydra as small as l/200^th of the original individual can make a complete animal without cell proliferation being involved. Thus even a few cells are able of forming a new organism; similarly in sponges a few archaeocytes are capable of regenerating a whole sponge body. The morphallactic procedure of regeneration is observed only in lower groups of animals. Animals with much more complex organisation regenerate their parts differently, generally by the production of a specialized bud or blastema.