Cephalopyge is a contraction of cephalus (Greek: κεφαλή kephale, "head") and pyge (πūγή, "behind") referring to the position of the anus close to the head. The species epithet trematoides … See more

Of the approximately 3000 species of nudibranch, the vast majority are benthic, only a couple are neustonic, and C. trematoides is very unusual in that it is pelagic. It is … See more

C. trematoides grows to 2.5 cm in length. It swims at approximately 12 cm/s, by passing several undulatory waves down its body each second. It is flattened and transparent; its … See more

• film of Cephalopyge swimming See more