- The body is bilaterally symmetrical, triploblastic and flattened.
- Body is thin, soft , leaf-like or ribbon-like.
- Circulatory and respiratory systems and skelton are absent.
- They are mostly parasites only a few are free living.
- They have an organ level of organization.
- The body has a soft covering with or without cilia.
- Hermaphrodite ,i.e. Both male and female reproductive organs occur in the same individual.
- There is no true internal body cavity or coelom, in which well developed organs can be accommodated.
For example : Free-living animals like planarians, or parasitic animals like liverflukes.
