[organisms] see Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
   Kingdom Animalia Linnaeus, 1758 - animals
     Branch Eumetazoa Butschli, 1910 see [unranked] Eumetazoa Bütschli, 1910
       Division Bilateria Hatschek, 1888 see Subkingdom Bilateria Hatschek, 1888
         Subdivision Protostomia Grobben, 1908 see Infrakingdom Protostomia Grobben, 1908
           Section Eucoelomata see Superphylum Eucoelomata
             Phylum Mollusca Linnaeus, 1758 - molluscs
               Class Gastropoda Cuvier, 1795 - snails and slugs
                 Subclass Opisthobranchia Milne-Edwards, 1848 - opisthobranchs see Order Opisthobranchia Milne-Edwards, 1848
                   1 Order Cephalaspidea Fischer, 1883
                   2 Order Anaspidea Fischer, 1883 - sea hares
                   3 Order Thecosomata Blainville, 1824 - shelled pteropods see Suborder Thecosomata Blainville, 1824
                   4 Order Gymnosomata Blainville, 1824 - naked pteropods see Suborder Gymnosomata Blainville, 1824
                   5 Order Notaspidea Fischer, 1883 see Suborder Notaspidea Fischer, 1883
                   6 Order Acochilidiacea
                   7 Order Sacoglossa Ihering, 1876 - sacoglossans
                   8 Order Nudibranchia Cuvier, 1814 - "true" nudibranchs