clade Thecosomata clade Gymnosomata clade Aplysiomorpha group Acochlidiacea clade Sacoglossa group Cylindrobullida clade Umbraculida Opisthobranchs s are a large and diverse group of specialized complex marine gastropods previously united under Opisthobranchia within the Heterobranchia, but no longer considered to represent a monophyletic grouping...
• (n. pl.) Alt. of Opisthobranchiata
[n] - gastropods having the gills when present posterior to the heart and having no operculum: includes sea slugs
subclass Opisthobranchia noun gastropods having the gills when present posterior to the heart and having no operculum: includes sea slugs; sea butterflies; sea hares