The Thecosomata, or sea butterflies, are a taxonomic suborder of small, pelagic, free-swimming sea snails known as holoplanktonic opisthobranch gastropod mollusks, in the order Pteropoda. Most pteropods have some form of calcified shell, although it is often very light, even translucent.
Sea angels are a large group of small free-swimming sea slugs, classified into six separate families. They are pelagic opisthobranchs in the clade Gymnosomata within the larger mollusc clade Heterobranchia. Sea angels were previously considered to be pteropods.
Limacina is a genus of swimming predatory sea snails commonly known as sea butterflies in the family Limacinidae. This genus contains some of the world's most abundant gastropod species.
Clione is a genus of small, floating sea slugs, pelagic marine gastropod mollusks in the family Clionidae, the sea angels.
Paedoclione doliiformis is a species of sea angel, a small floating sea slug, a pelagic marine gastropod mollusk in the family Clionidae.
Pteropoda are specialized free-swimming pelagic sea snails and sea slugs, marine opisthobranch gastropods. Most live in the top 10 m of the ocean and are less than 1 cm long. The monophyly of Pteropoda is the subject of a lengthy debate; they have even been considered as paraphyletic with respect to cephalopods. Current consensus, guided by molecular studies, leans towards interpreting the group as monophyletic.
The Buccinidae are a very large and diverse taxonomic family of large sea snails, often known as whelks or true whelks.
Lymnaea is a genus of small to large-sized air-breathing freshwater snails, aquatic pulmonate gastropod mollusks in the subfamily Lymnaeinae ( of the family Lymnaeidae, the pond snails.
Atlanta is a genus of pelagic marine gastropod molluscs in the family Atlantidae. They are sometimes called heteropods.
Turbo is a genus of large sea snails with gills and an operculum, marine gastropod molluscs in the family Turbinidae, the turban snails.
The family Cavoliniidae is a taxonomic group of small floating sea snails, pelagic marine opisthobranch gastropod mollusks.
Pupa is a genus of small sea snails, marine gastropod molluscs in the family Acteonidae.
Clione limacina, known as the naked sea butterfly, sea angel, and common clione, is a sea angel found from the surface to greater than 500 m (1,600 ft) depth. It lives in the Arctic Ocean and cold regions of the North Atlantic Ocean. It was first described by Friderich Martens in 1676 and became the first gymnosomatous "pteropod" to be described.
Vexillum is a genus of small to medium-sized sea snails, marine gastropod molluscs in the family Costellariidae.
Limacina helicina is a species of small swimming planktonic sea snail, in the family Limacinidae. It belongs to the group commonly known as sea butterflies (Thecosomata).
Limacina rangii is a species of swimming sea snail in the family Limacinidae, which belong to the group commonly known as sea butterflies (Thecosomata).
