Question

Morphallaxis is
a) Reconstruction of the whole body from a body part
b) growth of the lost limb
c)healing of the injury
d)regeneration with the help of blastema

Answer 1

Hint: Morphallaxis is the characteristic feature of the cnidaria. Morphallaxis occurs when regeneration is needed. Regeneration can be of two types including reparative and restorative. Reparative is the body’s ability to restore the damaged cells and restorative it the body’s ability to redevelop the whole body parts.

Complete answer:
Morphallaxis occurs when there is a need to regenerate the lost body tissue. It only occurs in the hydra of cnidaria. In hydra when its body is cut into pieces the body regenerates and forms new healthy individuals. The regenerated tissue develops from the already present tissue in the organisms’ body. That is why when a hydra gets cut or severed a new baby hydra gets formed from it and the new and the old cells are exchanged.

Additional Information: There are three types of regenerations that can be observed. Epimorphosis is a type of regeneration that occurs in the salamanders. In this new part, regeneration is called a blastema. When they lose the tail then the cells present at the blastemal end send signals to rapidly divide in order to form a new tail. The other type is found in the hydra where no blastemal region is present. And rearrangement of old and new cells leads to the formation of the full-body part. The other type of regeneration occurs in the planarians which are completely different from the epimorphosis and morphallaxis.
So, the answer is ‘reconstruction of whole-body from a body part’.

Note: When hydra gets cut into half then the head portion will regenerate the basal body and the basal body would regenerate the head part. Even if the hydra gets cut into many small pieces it has the capability to regenerate its whole body from that body part.