1) Planarians and liver flukes 1) Platyhelminthes 
A group of organisms comprising a whole phylum (Phylum Platyhelminths). Flatworms have flat bodies (as the name suggests) and are normally hermaphroditic. Phylum Platyhelminths consists of three classes: Class Trematoda (the flukes), Class Cestoda (the tapeworms) and Class Tubellaria (the free-living flatworms e.g., Planarians and ribbon worms).