Phylum Mollusca Linnaeus, 1758 - molluscs
   Subphylum Conchifera Gegenbauer, 1878
     Class Gastropoda Cuvier, 1795 - snails and slugs
       Subclass Orthogastropoda Ponder & Lindberg, 1995
         Superorder Heterobranchia Burmeister, 1837
           Order Opisthobranchia Milne-Edwards, 1848
             1 Suborder Cephalaspidea Fischer, 1883 - bubble snails see Order Cephalaspidea Fischer, 1883
             2 Suborder Sacoglossa Ihering, 1876 see Order Sacoglossa Ihering, 1876
             3 Suborder Anaspidea P. Fischer, 1883 - sea hares see Order Anaspidea Fischer, 1883
             4 Suborder Notaspidea Fischer, 1883
             5 Suborder Thecosomata Blainville, 1824 - shelled pteropods
             6 Suborder Nudibranchia Cuvier, 1814 - sea slugs see Order Nudibranchia Cuvier, 1814