a genus of marine invertebrates of the order Platyctenea, discovered in 1886 by the Russian zoologist A. A. Korotnev. The brightly colored body of Ctenoplana is greatly flattened; the mouth opening is located in the center of the side of the body that is directed toward the substratum. On the other side are located the organ of equilibrium (statocyst), eight short rows of comblike plates, and a pair of retractable tentacles. Ctenoplana creep along the bottom by constricting muscles or swim by beating the comblike plates. Previously Ctenoplana, along with Coeloplana metschnikowi and other Platyctenea, were considered a transitional group between the Ctenophora and the Turbellaria; now they are considered to be a specialized branch of the Ctenophora.