Platyhelminthes (from Ancient Greek πλατύ (platy) 'flat' and ἕλμινς (helmins) 'parasitic worm') is a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrates commonly called flatworms or flat worms. Being acoelomates (having no body cavity), and having no specialised circulatory and respiratory organs, they are restr…