phylum without freshwater or terrestrial representatives. Posted by Ramez.Leon at 8:04 AM No comments: Tuesday, November 20, 2007 Flatworms The flatworms (Phylum Platyhelminthes from the Greek platy, meaning "flat" and helminth, meaning worm) are a phylum of relatively simple soft-bodied invertebrate animals . With about 25,000 known species [1] they are