Planaria are non-parasitic flatworms of the biological family Planariidae, belonging to the order Seriata. Planaria are common to many parts of the world, living in both saltwater and freshwater ponds and rivers. Some species are terrestrial and are found under logs, in or on the soil, and on plants in humid areas. These animals move by beating cilia on the ventral dermis, allowing them to glide along on a film of mucus. Some move by undulations of the whole body by the contractions of muscles… (More on Planarian)