Rhinophores very small and lamellate, emerging from tall sheaths, into which they can be retracted. Each one is oar-like shape, with a cylindrical stem and a flattened distal blade. The tubercles are brown, and the branched appendages paler. This latter species is also large, but it is whitish, the cerata are bifurcated apically with black spots, and the oral veil is larger. The species of Melibe are specialized as predators upon crustaceans, which they trap with their oral hood.
Most species are capable of swimming by moving their body from side to side.
Many species gain additional nutrition from symbiotic zooxanthellae. The spawn formed a delicate colourless jelly-ribbon and contained spiralling strings of egg capsules. Each egg capsule contained up to 3 embryos, and the uncleaved ova measured about 110mm in diameter. The cerata of this species contain scattered defensive glands that secrete a characteristic hyaline slime, evident when handling the living animals. The Cymodocea beds where the species was present was located in a geothermally heated area, close to a specific biotope covered with bacterial mats more than 100m across.