REGENERATION:
Regeneration is the process of renewal, restoration, and growth of lost body parts.

ABILITY OF REGENERATION:
Depends on :

• Differentiation and Complexity

The more complex an organism the more will its cells be differentiated and lesser the power of regeneration.

PROCESS:

Some organisms are capable of dedifferentiation, in which specialized cells become more basic.
This process is involved in the regeneration of limbs in animals which are capable of this feat, with the basic cells differentiating again to construct the needed tissues, bones, and other types of cells for the replacement.

A small molecule dubbed reversine, has been discovered that has proven to induce dedifferentiation in myotubes. These dedifferentiated cells could then redifferentiate into osteoblasts and adipocytes.

EXAMPLES:
SPONGES:small parts can regenerate whole colonies.
HYDRA OR STARFISH:chopped parts can form new animal.

ARTHROPODS:can regenerate lost appendages.
SALAMANDERS AND LIZARDS:can regenerate lost tails.

BIRDS AND MAMMALS:new cells can form at points of wounds.