The Clionidae are a

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

sea angels Sea angels (clade Gymnosomata) are a large group of small free-swimming sea slugs, not to be confused with Cnidarians (Jellyfish and other similar creatures), classified into six different families. They are pelagic opisthobranchs in the clade Gy ...

, which are a group of

pelagic The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or wa ...

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military * ...

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

s. They resemble

angel In various theistic religious traditions an angel is a supernatural spiritual being who serves God. Abrahamic religions often depict angels as benevolent celestial intermediaries between God (or Heaven) and humanity. Other roles include ...

s, complete with flapping "wings", hence their common name. They are gelatinous, mostly transparent pteropods, and they only have shells in their embryonic stage. They are mostly very small, with the largest species (''

Clione limacina ''Clione limacina'', known as the naked sea butterfly, sea angel, and common clione, is a sea angel (pelagic sea slug) found from the surface to greater than depth.Gofas, S. (2012). ''Clione limacina''. Accessed through: World Register of Marine ...

'') reaching .

External anatomy

The Clionidae use winglike flaps for rhythmical locomotion, as if flying in the sea. These "wings" are attached to the anterior part of the body. The posterior part is gelatinous and mostly transparent. The orange visceral sac is confined to the anterior part.

Life habits

Mating is carried out ventrally for mutual fertilization. The following spring, this results in a free-floating, gelatinous egg mass.

Taxonomy

Clionidae

d'Orbigny Alcide Charles Victor Marie Dessalines d'Orbigny (6 September 1802 – 30 June 1857) was a French naturalist who made major contributions in many areas, including zoology (including malacology), palaeontology, geology, archaeology and anthropol ...

, 1851 is unfortunately also the name of a family of

sponge Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through t ...

s in the order

Hadromerida Heteroscleromorpha is a subclass of demosponges within the phylum Porifera Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms tha ...

, class

Demospongiae Demosponges (Demospongiae) are the most diverse class in the phylum Porifera. They include 76.2% of all species of sponges with nearly 8,800 species worldwide (World Porifera Database). They are sponges with a soft body that covers a hard, ...

. Within the

ICZN The International Code of Zoological Nomenclature (ICZN) is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals. It is also informally known as the ICZN Code, for its publisher, the I ...

there has been a proposed emendation of spelling to

Clionaidae Clionaidae is a family of demosponges which are found worldwide. This family is known for parasitically boring holes in calcareous material such as mollusc shells and corals, using both chemical and mechanical processes.Brusca, R.C. & Brusca, G. ...

for the sponge family. The ICZN has ruled the correct name of gastropod family is Clionidae Gray, 1847, with type genus ''

Clione ''Clione'' is a genus of small, floating sea slugs, pelagic marine gastropod mollusks in the family Clionidae, the sea angels.Gofas, S. (2012). Clione. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php? ...

'' Pallas, 1774. These two

subfamilies In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoologi ...

have been recognized in the taxonomy of Bouchet & Rocroi (2005): * subfamily Clioninae Rafinesque, 1815 - synonyms: Fowlerininae Pruvot-Fol, 1926 * subfamily Thliptodontinae, Kwietniewski, 1902 - synonyms: Pteroceanidae Meisenheimer, 1902; Cephalobranchiinae Pruvot-Fol, 1926

Genera

Genera within the family Clionidae include: subfamily Clioninae *''

'' Pallas, 1774 - type genus *'' Fowlerina'' Pelseneer, 1906 subfamily Thliptodontinae * '' Cephalobrachia'' Bonnevie, 1912 * ''

Thliptodon The Clionidae are a family of sea angels, which are a group of pelagic marine gastropods. They resemble angels, complete with flapping "wings", hence their common name. They are gelatinous, mostly transparent pteropods, and they only have she ...

'' Boas, 1886 subfamily ? *'' Paedoclione'' Danforth, 1907 - with the only species ''

Paedoclione doliiformis ''Paedoclione doliiformis'' is a species of sea angel, a small floating sea slug, a pelagic marine gastropod mollusk in the family Clionidae. ''Paedoclione doliiformis'' is the only species in the genus ''Paedoclione''.Paraclione ''Paraclione'' is a genus of " sea angels", small floating sea slugs, pelagic marine opisthobranch gastropod mollusks. They are very small and gelatinous, mostly transparent, and they only have a shell during their embryonic stage. They ca ...

'' Tesch, 1903 * ''Thalassopterus'' Kwietniewski, 1910 - with the only species '' Thalassopterus zancleus'' Kwietniewski, 1910Gofas, S. (2009). ''Thalassopterus zancleus'' Kwietniewski, 1910. In: Bouchet, P.; Gofas, S.; Rosenberg, G. World Marine Mollusca database. Accessed through the World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=139183 on 2010-09-16

References

External links

Movie of Clione limacina swimming
{{Authority control Taxa named by Constantine Samuel Rafinesque