Plakobranchidae Family

Family Plakobranchidae

In general the body shape is long and narrow, especially when crawling, and most often high in profile in relation to its width, although a very few are flattened. There is no shell in the adult. The sole of the foot is divided transversely into a short anterior section and a longer “viscera” section.
They have large, flap-like parapodia along each side of the body that extend from behind the head along most of the body length. These extend along the body for up to three quarters of its length and are folded over the dorsum often meeting in the dorsal midline but sometimes there are gaps where the margins are kept slightly apart. The parapodia are not used for swimming but can contain branches of the digestive system and function in respiration. These parapodia are sometimes enlarged with additional folding of the margins, or by possession of lobes or papillae along the margins.
The oral tentacles are quite small or absent whereas the rhinophores are usually prominent and auriculate with eye spots located at their base. There are no gills with gaseous exchange being effected across the integument of the large vascularised parapodia.
They feed primarily upon green algae.