Aphyonidae

Superregnum: Eukaryota
Cladus: Unikonta
Cladus: Opisthokonta
Cladus: Holozoa
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Megaclassis: Osteichthyes
Superclassis/Classis: Actinopterygii
Classis/Subclassis: Actinopteri
Subclassis/Infraclassis: Neopterygii
Infraclassis: Teleostei
Megacohors: Osteoglossocephalai
Supercohors: Clupeocephala
Cohors: Euteleosteomorpha
Subcohors: Neoteleostei
Infracohors: Eurypterygia
Sectio: Ctenosquamata
Subsectio: Acanthomorphata
Divisio/Superordo: Acanthopterygii
Subdivisio: Percomorphaceae
Series: Ophidiaria
Ordo: Ophidiiformes

Familia: Aphyonidae
Genera: Aphyonus - Barathronus - Meteoria - Nybelinella - Paraphyonus – Parasciadonus - Sciadonus
Name

Aphyonidae Jordan & Evermann, 1898

Type genus: Aphyonus Günther, 1878

References

Jordan, D.S. & Evermann, B.W., 1898: The fishes of North and Middle America: a descriptive catalogue of the species of fish-like vertebrates found in the waters of North America north of the Isthmus of Panama. Part III. Bulletin of the United States National Museum, 47: i-xxiv + 2183a-3136. BHLReference page.
Nielsen, J.G. 2017. Revision of the genus Nybelinella (Teleostei, Bythitidae) with a new Atlantic, abyssal species. Zootaxa 4247(1): 45–54. DOI: 10.11646/zootaxa.4247.1.4. Reference page.
Van der Laan, R., Eschmeyer, W.N. & Fricke, R. 2014. Family-group names of Recent fishes. Zootaxa 3882(1): 1–230. DOI: 10.11646/zootaxa.3882.1.1 Reference page.

Links

Froese, R. and D. Pauly. Editors. 2006. FishBase, version (02/2006). [1]

Aphyonidae is a family of eel-like fishes in the order Ophidiiformes. They are found in tropical and subtropical waters throughout the world. They are deep-sea fishes, living between 2,000 metres (6,600 ft) and 6,000 metres (20,000 ft) depth.[2]
Description and biology

Aphyonids are small fishes, typically about 10 centimetres (3.9 in) long when fully grown. They have transparent, gelatinous skin, which lacks any scales. The dorsal, caudal and anal fins are united into a single ribbon. Most species are neotenic, showing a number of features as adults that are more commonly associated with fish larvae. For example, the skeleton is only partially calcified, and the muscles and gills are underdeveloped. The eyes, nasal organ and lateral line are also reduced, and they lack a swim bladder.[2]

The aphyonids are viviparous, giving birth to live young. The males bundle their sperm into small sacs (spermatophores), so that they can be stored for extended periods. This allows them to mate with immature females, which can then store the sperm inside the ovaries until they reach sexual maturity, and the eggs are ready to be fertilised. This unusual adaptation is likely a response to the difficulty of finding a mate in their dark and sparsely inhabited deep-sea environment.[2]
References

Nielsen, J.G. (2015): Revision of the aphyonid genus Aphyonus (Teleostei, Ophidiiformes) with a new genus and two new species. Zootaxa, 4039 (2): 323–344.
Nielsen, J.G. (1998). Paxton, J.R.; Eschmeyer, W.N. (eds.). Encyclopedia of Fishes. San Diego: Academic Press. p. 134. ISBN 0-12-547665-5.