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.
Opisthobranchs is a now informal name for a large and diverse group of specialized complex gastropods which used to be united in the subclass Opisthobranchia. That taxon is no longer considered to represent a monophyletic grouping.
Heterobranchia, the heterobranchs, is a taxonomic clade of snails and slugs, which includes marine, aquatic and terrestrial gastropod mollusks.
Pulmonata or pulmonates, is an informal group of snails and slugs characterized by the ability to breathe air, by virtue of having a pallial lung instead of a gill, or gills. The group includes many land and freshwater families, and several marine families.
Amphiboloidea is a taxonomic superfamily of air-breathing land snails.
Euthyneura is a taxonomic infraclass of snails and slugs, which includes species exclusively from marine, aquatic and terrestrial gastropod mollusks in the clade Heterobranchia.
Lower Heterobranchia, also known as the Allogastropoda, is a group of rather specialized, highly evolved sea slugs and sea snails, within the subclass Heterobranchia.
Nudipleura are a clade of sea snails and sea slugs, marine gastropod mollusks within the large clade Heterobranchia.
Acochlidiacea, common name acochlidians, are a taxonomic clade of very unusual sea snails and sea and freshwater slugs, aquatic gastropod mollusks within the large clade Heterobranchia. Acochlidia is a variant spelling.
Runcinoidea is a taxonomic superfamily or a clade Runcinaecea of sea slugs, marine gastropod mollusks in the order Runcinida
Acochlidiidae are a taxonomic family of shell-less freshwater gastropods, aquatic gastropod mollusks within the clade Acochlidiacea.
This overview lists proposed changes in the taxonomy of gastropods at the family level and above since 2005, when the taxonomy of the Gastropoda by Bouchet & Rocroi (2005) was published. In other words, these are recent updates in the way various groups of snails and slugs are classified.
Acochlidium fijiiensis is a species of freshwater gastropod, an aquatic gastropod mollusc within the family Acochlidiidae. Acochlidium fijiiensis has no shell.
Pseudunela is a genus of minute sea slugs, acochlidians, shell-less marine or temporary brackish or brackish gastropod mollusks in the clade Acochlidiacea.
Aiteng ater is a species of sea slug, a marine gastropod mollusc in the family Aitengidae. The specific name ater is from the Latin language and means black, in reference to the appearance of the slug on the mud.
Panpulmonata is a taxonomic clade of snails and slugs in the clade Heterobranchia within the clade Euthyneura.
Aiteng mysticus is a species of sea slug in the family Aitengidae, found around Hisamatsu, Miyako-jima, Okinawa, Japan. Morphologically it clearly belongs to the Aitengidae, but it shows differences to Aiteng ater at genus or species level. Its affinity to Aiteng ater is confirmed by comparison of the mitochondrial 16S rRNA sequences.
Pontohedyle is a genus of sea slugs, acochlidians, shell-less marine gastropod mollusks in the family Microhedylidae. Sea slugs in this genus are highly simplified and uniform.
Pseudunela marteli is a species of sea slug, an acochlidian, a shell-less marine gastropod mollusk in the family Pseudunelidae.
Aiteng marefugitus is a species of fully terrestrial sea slug found only on the Ulong Island of Palau. The species name is derived from latin, meaning "fled from the sea".
