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n.1.(Zool.) A genus of transparent marine annelids which swim actively at the surface of the sea. They have deeply divided or forked finlike organs (parapodia). This genus is the type of the order, or suborder, Gymnocopa.
References in periodicals archive ?
Cover photo: Tomopteris, a genus of sea worms that emits blue light, but one species can produce yellow.
The least transparent tissues were from the pelagic gastropods (excluding Clione) (17%) and Tomopteris (9.