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 Mollusca Linnaeus, 1758 - molluscs
           Class Gastropoda Cuvier, 1795 - snails and slugs
             Subclass Opisthobranchia Milne-Edwards, 1848 - opisthobranchs see Order Opisthobranchia Milne-Edwards, 1848
               Order Gymnosomata Blainville, 1824 - naked pteropods see Suborder Gymnosomata Blainville, 1824
                 1 Family Pneumodermatidae Latreille, 1825
                 2 Family Notobranchaeidae Pelseneer, 1886
                 3 Family Cliopsidae Costa, 1873
                 4 Family Clionidae Rafinesque, 1815
                 5 Family Thliptodontidae Kwietniewski, 1902 (1902) see Subfamily Thliptodontinae Kwietniewski, 1902 (1902)
                 6 Family Hydromylidae Pruvot-Fol, 1942 (1862)
                 7 Family Laginiopsidae Pruvot-Fol, 1922