With the help of a diagram only show regeneration in Planaria. Regeneration is not possible in all types of animals. Why?

The ability to give rise to new individuals from their body parts is called regeneration. If the body of Planaria is somehow cut or broken up into many pieces, each piece grows into a complete organism. Regeneration is not possible in all types of animals because it is only possible in animals with specialized cells which cells proliferate and make large numbers of cells.