Eureka Moment: Tail Piece of Earthworm Survived for 81 Days

Earthworm was amputated in head and tail piece in an experiment done by @Misbah et al, it was found that tail piece survived for 81 days and head piece lived for not more than 100 years.
The question which came was how earthworm tail surviving without feeding, on discussing further the question came whether they are healing and developing a mouth to the tail piece? On looking at literature we came to know that earthworm may be digesting the stored fats by taking up oxygen and producing energy to survive.

We are yet to find out exactly how did tail piece survive, the possibilities are,

  1. It uses stored fats and survives
  2. It recreates its mouth and survives by feeding

Lets design experiments to find out which possibility is true!