Phylum Platyhelminthes: Platyhelminthes is a phylum of dorsoventrally flattened acoelomate but triploblastic animals having bilateral symmetry and blind sac body plan. Due to their flattened nature, Platyhelminthes are also called flatworms. The term Platyhelminthes was coined by Gegenbaur (1859). Characteristics of Phylum Platyhelminthes: Flatworms are free-living commensal or parasitic organisms. The free-living worms may be