Bilateria Hatschek, 1888 - bilaterians see Subkingdom Bilateria Hatschek, 1888
   Ecdysozoa Aguinaldo, Turbeville, Linford, Rivera, Garey, Raff & Lake 1997, nom. cl. inval. - ecdysozoans see Clade Ecdysozoa Aguinaldo, Turbeville, Linford, Rivera, Garey, Raff & Lake 1997 [Lake, Halanych, Servin & Garey 2020]
     Introverta Nielsen, 1995
       Nematoida Rudolphi, 1808
         1 Phylum Nematoda Gegenbaur, 1859 - round worms
         2 Phylum Nematomorpha Vejdovsky, 1886 - horsehair worms