noun
opisthobranchs
A taxonomic group of marine gastropods; used in biological contexts.
後鰓類にはウミウシやアメフラシが含まれる。
Opisthobranchs include sea slugs and sea hares.
From 後 (after) + 鰓 (gill) + 類 (group), referring to the posterior gill position characteristic of this group.