living organisms see Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
   Superkingdom Eukaryotae see Domain Eukaryota Chatton, 1925
     Kingdom Animalia Linnaeus, 1758 - animals
       Subkingdom Eumetazoa Butschli, 1910 see [unranked] Eumetazoa Bütschli, 1910
         Phylum Annelida Lamarck, 1809 - segmented worms
           Class Polychaeta Grube, 1850 - polychaetes
             Order Spionida Rouse & Fauchald, 1997
               1 Family Apistobranchidae Mesnil & Caullery, 1898
               2 Family Spionidae Grube, 1850
               3 Family Trochochaetidae Pettibone, 1963
               4 Family Poecilochaetidae Hannerz, 1956
               5 Family Heterospionidae O. Hartman, 1965 see Family Longosomatidae Hartman, 1944