The Clionidae are a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

sea angels A sea is a large body of salt water. There are particular seas and the sea. The sea commonly refers to the ocean, the interconnected body of seawaters that spans most of Earth. Particular seas are either marginal seas, second-order section ...

, 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. The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or water column between the sur ...

marine

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

s. They resemble

angel An angel is a spiritual (without a physical body), heavenly, or supernatural being, usually humanoid with bird-like wings, often depicted as a messenger or intermediary between God (the transcendent) and humanity (the profane) in variou ...

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'') 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 or sea sponges are primarily marine invertebrates of the animal phylum Porifera (; meaning 'pore bearer'), a basal clade and a sister taxon of the diploblasts. They are sessile filter feeders that are bound to the seabed, and a ...

s in the order

Hadromerida Heteroscleromorpha is a Subclass (biology), subclass of demosponges within the phylum Sponge, Porifera. Heteroscleromorpha has the most taxa of the demosponge subclasses, with an estimated 7500 species. References

Heteroscleromorpha, ...

, class

Demospongiae Demosponges or common sponges are sponges of the class Demospongiae (from + ), the most diverse group in the phylum Porifera which include greater than 90% of all extant sponges with nearly 8,800 species worldwide (according to the World P ...

. 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 formal author, t ...

there has been a proposed emendation of spelling to

Clionaidae Clionaidae is a family of ectoparasitic demosponges which are found worldwide. This group of sponges are well known for boring holes in calcareous material such as mollusc shells and coral Corals are colonial marine invertebrates within the ...

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.ph ...

'' 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 botanical subfamily names with "-oideae", and zool ...

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'' Boas, 1886 subfamily ? *'' Paedoclione'' Danforth, 1907 – with the only species '' Paedoclione doliiformis'' Danforth, 1907 *'' Paraclione'' 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