Ilyophinae, the arrowtooth ells or mustard eels, is a

subfamily 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 zo ...

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 belongiing to the

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 ...

Synaphobranchidae Cutthroat eels are a family, Synaphobranchidae, of eels, the only members of the suborder Synaphobranchoidei. They are found worldwide in temperate and tropical seas. Cutthroat eels range from in length. They are bottom-dwelling fish, found in ...

, the cutthroat eels. Within its family this subfamily shows greatest number of species and the greatest morphological diversity.

Taxonomy

The Ilyophinae was first proposed as the family Ilyophididae in 1891 by the American

ichthyologist Ichthyology is the branch of zoology devoted to the study of fish, including bony fish (Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha). According to FishBase, 35,800 species of fish had been described as of March 2 ...

David Starr Jordan David Starr Jordan (January 19, 1851 – September 19, 1931) was the founding president of Stanford University, serving from 1891 to 1913. He was an ichthyologist during his research career. Prior to serving as president of Stanford Universi ...

and Bradley Moore Davis, this taxon has also been known as the Dysommidae, or Dysomminae, but this name was proposed by

Theodore Gill Theodore Nicholas Gill (March 21, 1837 – September 25, 1914) was an American ichthyologist, mammalogist, malacologist, and librarian. Career Born and educated in New York City under private tutors, Gill early showed interest in natural hist ...

but Jordan and Davi's name has priority. It is now regarded as a subfamily of the cutthroat eel family, Synaphobranchidae, within the eel

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

Anguilliformes Eels are ray-finned fish belonging to the order (biology), order Anguilliformes (), which consists of eight suborders, 20 Family (biology), families, 164 genus, genera, and about 1000 species. Eels undergo considerable development from the earl ...

Etymology

Ilyophinae has a name based on that of its type genus ''Ilyophis'', this name combines ''ilys'' which is

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

for "mud", probably an allusion to the soft, silty substrate habitat of '' I. brunneus'', with ''ophis'', meaning "serpent", referring to the snake-like shape of eels.

Genera

The Ilyophinae contains the following genera:

Characteristics

Ilyophinae eels are caharcterised by having a lower jaw that is shorter than the upper jaw. In most taxa the upper body lacks scales and in some ''Dysomma'' species as well as ''Thermobiotes'' do not have a

pectoral fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish aquatic locomotion, swim. Apart from the tail or caudal fin, fish fins have no direct connection with the vertebral column ...

. They have depressed, relatively rounded heads with some rather long teeth. These eels show very variable body shapes, dentition, whether they possess pectoral fins, the size of the eyes and the structure of the snout. In some species, the anus is positioned rather far forward on the body, almost beneath the pectoral fins, if any.

Distribution and habitat

Ilyophinae eels are benthic species found in deeper waters in the Atlantic, Indian and Pacific Oceans. They are known to form large aggregations in seamounts and thermal vents, known as eel cities.

References

{{taxonbar, from=Q1659279 Synaphobranchidae Taxa named by Theodore Gill Ray-finned fish subfamilies