Abstract
Recent studies on marine microturbellarians are surveyed and summarized. The microturbellarians consist of eight orders such as Nemertodermatida, Acoela, Catenulida, Macrostomida, Lecithoepitheriata, Prolecithophora, Proseriata, and Neorhabdocoela. The systematics of the worms becomes a major field in research work especially since the last few decades. This is considered to be mainly ascribed to discovery of rich interstitial fauna including the turbellarians. In this consequence the systematics has brought a remarkable advancement of both electron-microscopial and ecological study (life-cycle, distribution pattern, population structure, abundance dynamics, etc.). These studies have enables us to adopt a more detailed comparative method for clarifying the phylogeny of the Turbellaria.
