Sea slug is a common name for some marine invertebrates with varying levels of resemblance to terrestrial slugs. Most creatures known as sea slugs are gastropods, i.e. they are sea snails that over evolutionary time have either completely lost their shells, or have seemingly lost their shells due to having a greatly reduced or internal shell. The name "sea slug" is most often applied to nudibranchs, as well as to a paraphyletic set of other marine gastropods without obvious shells.
The Systellommatophora is a clade of primitive, air-breathing slugs, according to the taxonomy of the Gastropoda.
Onchidiidae are a family of small, air-breathing sea slugs. They are shell-less marine pulmonate gastropod molluscs. Onchidiidae is the only family within the superfamily Onchidioidea.
Onchidella nigricans is a species of small, air-breathing sea slug, a shell-less marine pulmonate gastropod mollusc in the family Onchidiidae.
Onchidella carpenteri is a species of air-breathing sea slug, a shell-less marine pulmonate gastropod mollusk in the family Onchidiidae.
Paraoncidium chameleon is a species of air-breathing sea slug, a shell-less marine pulmonate gastropod mollusk in the family Onchidiidae.
Semperoncis glabra is a species of air-breathing sea slug, a shell-less marine pulmonate gastropod mollusk in the family Onchidiidae.
Onchidella armadilla is a species of air-breathing sea slug, a shell-less marine pulmonate gastropod mollusk in the family Onchidiidae.
Onchidella steindachneri is a species of air-breathing sea slug, a shell-less marine pulmonate gastropod mollusk in the family Onchidiidae.
Peronia peronii is a species of air-breathing sea slug, a shell-less marine pulmonate gastropod mollusk in the family Onchidiidae.
Onchidium vaigiense is a species of air-breathing sea slug, a shell-less marine pulmonate gastropod mollusk in the family Onchidiidae.
Peronia verruculata is a species of air-breathing sea slug, a shell-less marine pulmonate gastropod mollusk in the family Onchidiidae.
Onchidella indolens is a species of air-breathing sea slug, a shell-less marine pulmonate gastropod mollusk in the family Onchidiidae.
Onchidium is a genus of air-breathing sea slugs, shell-less marine pulmonate gastropod mollusks in the family Onchidiidae. There are only four species currently recognized in the genus.
Patella ferruginea, commonly known as the ferruginous limpet is a species of true limpet, a marine gastropod mollusk in the family Patellidae. It is a large limpet, endemic to the western Mediterranean Sea, and although common in the past, it is now rare and restricted to only a few locations.
Onchidina is a monotypic genus of air-breathing sea slugs, a shell-less marine pulmonate gastropod mollusks in the family Onchidiidae. Its sole member is the species Onchidina australis. Uniquely within the Onchidiidae, O. australis lives above the tidal zone in a fully terrestrial habitat.
Peronia is a genus of air-breathing sea slugs, a shell-less marine pulmonate gastropod mollusks in the family Onchidiidae. These slugs differ from other onchidiid slugs in having branched "gills" on their dorsal side, although these can be retracted. More than two dozen species of Peronia have been described from the Indo-West Pacific, but a recent revision of the genus determined that 21 of these names are synonyms. Nine species of Peronia are recognized, most of which can differentiated only by examining their internal anatomy or with DNA sequencing.
Semperoncis is a genus of air-breathing sea slugs, a shell-less marine pulmonate gastropod mollusks in the family Onchidiidae.
Lessonina is a genus of air-breathing sea slugs, a shell-less marine pulmonate gastropod mollusks in the family Onchidiidae.
Platevindex burnupi is a species of air-breathing sea slug, a shell-less marine pulmonate gastropod mollusk in the family Onchidiidae.
