Planarians [Order Tricladida] are best known for their capacity to regenerate complete individuals from minuscule parts. For instance, a small fragment removed from the flank of a planarian is capable of re-specifying its parts to regain bilateral symmetry and dynamically reset positional values of cells to produce a normal, properly proportioned animal.
This extraordinary regeneration capability is enabled by somatic stem cells, called neoblasts, that are distributed throughout the planarian body.
Planarians can survive prolonged starvation through complex mechanisms of selective destruction and de-differentiation of body organs, with gradual decrease in body size of the organism.