A better understanding of the mechanisms underlying growth and degrowth in freshwater planarians, and the control systems associated with them, requires a thorough investigation at the cellular and molecular levels. As a first step towards this goal, we have measured the body volume, plan area, number of cells, percentage of different cell types and mean cell area and volume in growing and degrowing organisms from five species of planarians with sexual, asexual, semelparous and iteroparous reproduction.