2)Body having 3 layers of tissues with organs and organelles.
3)Body contains no internal cavity.
4)Possesses a blind gut (i.e. it has a mouth but no anus)
5)Has Protonephridial excretory organs instead of an anus.
6)Has normally a nervous system of longitudinal fibres rather than a net.
7)Generally dorsoventrally flattened.
8)Reproduction mostly sexual as hermaphrodites.
9)Mostly they feed on animals and other smaller life forms.
10)Some species occur in all major habitats, including many as parasites of other animals.