Aplysiidae is the only family in the superfamily Aplysioidea, within the clade Anaspidea. These animals are commonly called sea hares because, unlike most sea slugs, they are often quite large, and when they are underwater, their rounded body shape and the long rhinophores on their heads mean that their overall shape resembles that of a sitting rabbit or hare. Sea hares are however sea snails with shells reduced to a small plate hidden between the parapodia, and some species are extremely large. The Californian black sea hare, Aplysia vaccaria is arguably the largest living gastropod species, and is certainly the largest living heterobranch gastropod.
Tiberia is a genus of minute parasitic sea snails, marine gastropod molluscs in the family Pyramidellidae, the pyrams and their allies. Tiberia is the only genus in the tribe Tiberiini.
Doridoidea, commonly known as dorid nudibranchs, are a taxonomic superfamily of medium to large, shell-less sea slugs, marine gastropod mollusks in the clade Doridacea, included in the clade Nudibranchia.
The Chromodorididae, or chromodorids, are a taxonomic family of colourful, sea slugs; dorid nudibranchs, marine gastropod mollusks in the superfamily Doridoidea. “Chromodorid nudibranchs are among the most gorgeously coloured of all animals.” The over 360 described species are primarily found in tropical and subtropical waters, as members of coral reef communities, specifically associated with their sponge prey. The chromodorids are the most speciose family of opisthobranchs. They range in size from <10mm to over 30 cm, although most species are approximately 15–30 mm in size.
Neritidae, common name the nerites, is a taxonomic family of small to medium-sized saltwater and freshwater snails which have a gill and a distinctive operculum.
Limapontiidae is a taxonomic family of small to minute sacoglossan sea slugs. These are marine opisthobranch gastropod mollusks.
Plakobranchidae is a family of sea slugs, marine opistobranch gastropod mollusks in the superfamily Plakobranchoidea. They superficially resemble nudibranchs but they are sacoglossans, members of the clade Sacoglossa within the Opisthobranchia.
Pyramidelloidea is a superfamily of mostly very small sea snails, marine gastropod mollusks and micromollusks within the clade Panpulmonata.
Ellobiidae, common name the hollow-shelled snails, is a family of small air-breathing land snails, terrestrial pulmonate gastropod mollusks in the clade Eupulmonata. Ellobiidae is the only family in the superfamily Ellobioidea, according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005).
Neritiliidae is a family of submarine cave snails, marine gastropod mollusks or micromollusks in the clade Cycloneritimorpha.
Tergipedidae is a family of sea slugs, aeolid nudibranchs, marine gastropod molluscs in the superfamily Fionoidea.
Melibe is a genus of sea slugs, nudibranchs, marine gastropod mollusks in the family Tethydidae.
Arminidae is a family of sea slugs, marine gastropod mollusks in the superfamily Arminoidea.
Scyllaeidae is a taxonomic family of sea slugs, nudibranchs, marine gastropod mollusks in the superfamily Tritonioidea.
The Cladobranchia are a taxonomic clade of nudibranchs, sea slugs, marine gastropod molluscs in the clade Dexiarchia.
Litiopidae, common name litiopids, is a family of small sea snails, marine gastropod molluscs in the clade Sorbeoconcha.
Tethys fimbria is a species of predatory sea slug, a nudibranch, a marine gastropod mollusk in the family Tethydidae.
Tethys is a genus of sea slugs, nudibranchs, marine gastropod mollusks in the family Tethydidae.
The family Cliidae is a taxonomic group of small floating sea snails, pelagic marine opisthobranch gastropod mollusks.
Melibe papillosa is a species of sea slug, a nudibranch, a marine gastropod mollusk in the family Tethydidae. This species is yellowish and somewhat translucent. The oral hood, which is large, has flattened hatchet-shaped cerata. It is found in the waters around Japan.
