Opistobranch

Opisthobranchia Temporal range: Carboniferous–Recent PreЄ Є O S D C P T J K Pg N
Aegires minor
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
(unranked):	clade Heterobranchia informal group "Opisthobranchia" Milne-Edwards, 1848
Included groups
clade Cephalaspidea clade Thecosomata clade Gymnosomata clade Aplysiomorpha group Acochlidiacea clade Sacoglossa group Cylindrobullida clade Umbraculida clade Nudipleura

clade Cephalaspidea
clade Thecosomata
clade Gymnosomata
clade Aplysiomorpha
group Acochlidiacea
clade Sacoglossa
group Cylindrobullida
clade Umbraculida
clade Nudipleura

Opisthobranchs (/əˈpɪsθəˌbræŋks, -θoʊ-/) are a large and diverse group of specialized complex gastropods that used to be united in the subclass Opisthobranchia, but are no longer considered to represent a monophyletic grouping because it contains land snails and slugs, the Pulmonata.Euopisthobranchia is a revised collection of opisthobranchs that is monophyletic, but this group leaves out some "traditional" opisthobranchs including the Sacoglossa and the Acochlidiacea. The subclass Heterobranchia now contains the species which used to be assigned to Opisthobranchia plus the Pulmonata.