The Stephanoberycoidei is a

suborder Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized ...

of marine

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...

es, consisting of about 68 species, the majority (61) of which belong to the

ridgehead Ridgeheads, also known as bigscales, are a family (Melamphaidae, from the Greek ''melanos'' lackand ''amphi'' y both sides of small, deep-sea beryciform fish. The family contains approximately 37 species in five genera; their distribution is ...

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 ...

(Melamphaidae). They were formerly placed as their own order, the Stephanoberyciformes. However, more recent taxonomic sources treat them as a suborder of the Beryciformes. The Stephanoberyciformes are mostly uncommon

deep-sea The deep sea is broadly defined as the ocean depth where light begins to fade, at an approximate depth of or the point of transition from continental shelves to continental slopes. Conditions within the deep sea are a combination of low tempe ...

species with little, if any, importance to commercial

fishery Fishery can mean either the enterprise of raising or harvesting fish and other aquatic life or, more commonly, the site where such enterprise takes place ( a.k.a., fishing grounds). Commercial fisheries include wild fisheries and fish far ...

. They share many morphological similarities with the Berycoidei, their sister order. They are usually found in Australian waters. The

whalefish The Cetomimoidea or whalefishes are a superfamily of small, deep-sea ray-finned fish. Formerly treated as either their own order (Cetomimiformes) due to their unusual anatomy, more recent studies incorporating genetic data confirm them to be dee ...

es, which were formerly treated as their own order, are now also placed in this group. Some families treat them as a superfamily within the group named Cetomimoidea; most taxa traditionally placed here would then be the Stephanoberycoidea. The

families Family (from ) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictability, structure, and safety as ...

are: * Family

Stephanoberycidae Stephanoberycidae, the pricklefishes are a family of fishes in the order Beryciformes. They are found in tropical and subtropical waters of the Atlantic and Pacific Oceans, and to the Indian Ocean off the coast of South Africa. They are deep-w ...

Gill A gill () is a respiration organ, respiratory organ that many aquatic ecosystem, aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow r ...

, 1884 (pricklefishes) * Family

Hispidoberycidae ''Hispidoberyx ambagiosus'', the bristlyskin, is a species of spiny-scale pricklefish found in the Indian and Pacific Oceans at depths from . This species grows to standard length Fish measurement is the measuring of individual fish and vario ...

Kotlyar, 1981 (spiny-scale pricklefishes) * Family Gibberichthyidae Parr, 1933 (gibberfishes) * Family

Rondeletiidae The redmouth whalefishes are two species of deep-sea whalefishes in the genus ''Rondeletia'', the only genus in the family Rondeletiidae. They are apparently close to the velvet whalefish (''Barbourisia rufa''), and apparently also to the gibber ...

Goode &

Bean A bean is the seed of some plants in the legume family (Fabaceae) used as a vegetable for human consumption or animal feed. The seeds are often preserved through drying (a ''pulse''), but fresh beans are also sold. Dried beans are traditi ...

, 1895 (redmouth whalefishes) * Family Barbourisiidae Parr, 1945 (redvelvet whalefishes) * Family Cetomimidae Goode & Bean, 1895 (whalefishes or flabby whalefishes) Common characteristics include; a generally rounded body, a toothless

palate The palate () is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but in most other tetrapods, the oral and nasal cavities are not truly sep ...

, rather thin

skull The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate. In the human, the skull comprises two prominent ...

bones, and a missing orbitosphenoid bone (except for ''

Hispidoberyx ''Hispidoberyx ambagiosus'', the bristlyskin, is a species of spiny-scale pricklefish found in the Indian and Pacific Oceans at depths from . This species grows to standard length Fish measurement is the measuring of individual fish and vario ...

''). The gibberfishes on the other hand appear to be closer to whalefishes such as '' Rondeletia'', as has been proposed time and again. These two groups have - apparently as only living fishes - the mysterious Tominaga's organ (A large mass of globular white tissue, that is present anterior to the orbit and posterior and medial to the nostrils and nasal rosette). ''Rondeletia'', meanwhile, is suspected to be very close to the

velvet whalefish The velvet whalefish (''Barbourisia rufa'') is a deep-sea whalefish, the sole known member of its family Barbourisiidae. It is found throughout the tropical and temperate parts of the world's oceans, mainly in the Pacific near Japan and New Zeala ...

, ''Barbourisia rufa''. Despite their distinctive appearance, this clade is only thought to have diverged from the Berycoidei during the

Paleocene The Paleocene ( ), or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), ...

. Potentially the earliest fossil record of the group is of a '' Rondeletia''-like whalefish from the earliest Eocene-aged

Fur Formation The Fur Formation is a marine geological formation of Ypresian ( Lower Eocene Epoch, c. 56.0-54.5 Ma) age which crops out in the Limfjord region of northern Denmark from Silstrup via Mors and Fur to Ertebølle, and can be seen in many cliffs and ...

of Denmark.

Footnotes

References

* (2006): ''

Fishes of the World ''Fishes of the World'' is a standard reference for the systematics of fishes. It was first written in 1976 by the American ichthyologist Joseph S. Nelson (1937–2011). Now in its fifth edition (2016), the work is a comprehensive overview of t ...

'' (4th ed.). * (2001): Larvae and juveniles of the deepsea "whalefishes" ''Barbourisia'' and ''Rondeletia'' (Stephanoberyciformes: Barbourisiidae, Rondeletiidae), with comments on family relationships. ''Records of the Australian Museum'' 53(3): 407-425
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External links

* {{Taxonbar, from=Q621519 Beryciformes