"An invertebrate animal belonging to a group of phyla that are distinguished by the lack of a well-developed coelom and blood vessels. Most are minute worm-like animals, including the nematodes, rotifers, and water bears", From modern LatinAschelminthes (former phylum name), from Greek askos 'sac' + helminth 'worm' (from the former belief that animals of this group had a fluid-filled internal sac).[aschelminth etymology, aschelminth origin, 英语词源]