Platyhelminthes are best described as
Triploblastic, acoelomate flatworms
General Characteristics of the phylum Platyhelminthes
(Platys: flat; helminthes: worms)
Kingdom: Animalia.
Habitat: mostly parasitic, few are free living in sea or fresh water.
Grade of organization: Organ- system grade of organization.
Symmetry: Bilateral symmetry and Body is dorso-ventrally flattened.
Germ layer: Triploblastic. ...
Coelom: Absent (acoelomate).