subclass opisthobranchia(n = noun.animal) opisthobranchia - gastropods having the gills when present posterior to the heart and having no operculum: includes sea slugs; sea butterflies; sea hares;
is a kind of class
is a member of class gasteropoda, class gastropoda, gasteropoda, gastropoda

opisthobranchia, subclass, subclass acnidosporidia, subclass actinopoda, subclass alismatidae, subclass amphineura, subclass anapsida, subclass archaeornithes, subclass archosauria, subclass arecidae, subclass asteridae, subclass branchiopoda, subclass caryophyllidae, subclass cirripedia, subclass cnidosporidia, subclass commelinidae, subclass copepoda, subclass crossopterygii, subclass diapsida, subclass dibranchia, subclass dibranchiata, subclass dilleniidae, subclass dipnoi, subclass discomycetes, subclass elasmobranchii, subclass entomostraca, subclass euascomycetes, subclass euryalida, subclass eutheria, subclass exopterygota, subclass hamamelidae, subclass heterobasidiomycetes, subclass holocephali, subclass homobasidiomycetes, subclass infusoria, subclass lepidosauria, subclass liliidae, subclass magnoliidae, subclass malacostraca, subclass metatheria, subclass ophiurida, subclass ostracoda, subclass pantotheria, subclass phytomastigina, subclass prototheria, subclass rhizopoda, subclass rosidae, subclass selachii, subclass synapsida, subclass teleostei, subclass telosporidia, subclass zoomastigina