Sacoglossa, commonly known as the sacoglossans or the "sap-sucking sea slugs", are a clade of small sea slugs and sea snails, marine gastropod mollusks that belong to the clade Heterobranchia. Sacoglossans live by ingesting the internal contents of algae, hence the adjective "sap-sucking".
Some sacoglossans simply digest the sap which they suck from the algae, but in some other species the slugs sequester and utilize within their own tissues, living chloroplasts from the algae they eat, a very unusual phenomenon known as kleptoplasty. This earns them the title of the "solar-powered sea slugs", and makes them unique among animals.
The Sacoglossa are divided into two clades: the shelled families (Oxynoacea) and the shell-less families (Plakobranchacea). There are four families of shelled species: Cylindrobullidae, Volvatellidae, Oxynoidae and Juliidae, the bivalved gastropods. Saccoglossans are distinguished from related groups by the presence of a single row of teeth on the radula. The teeth are adapted for the suctorial feeding habits of the group.
Kathe R. Jensen (2007) recognized 284 valid species within the Sacoglossa.
Read more about Sacoglossa: Appearance, Distribution, Use of Ingested Cellular Material, Oxynoacea, Plakobranchoidea, Evolution