''Monognathus'', or onejaw, is the only genus of the family Monognathidae of

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 ...

eel Eels are ray-finned fish belonging to the order Anguilliformes (), which consists of eight suborders, 20 families, 164 genera, and about 1000 species. Eels undergo considerable development from the early larval stage to the eventual adult stage ...

s. The name comes from the

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 ...

''monos'' meaning "one" and ''gnathos'' meaning "jaw", a reference to the large mouth in comparison with the rest of the fish, and also the absence of an upper jaw (

maxilla In vertebrates, the maxilla (: maxillae ) is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxil ...

and

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammals h ...

bones are absent).

Description

The

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage The fus ...

and

anal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported o ...

s lack bony supports and the

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 ...

s are missing. The snout has a fang connected to glands, which are venomous in adults. These eels are virtually blind, with rudimentary eyes and small olfactory organs, although the male olfactory organs are enlarged, perhaps suggesting a method of "sniffing out" a mate. Typical lengths are from 4 to 10 cm (1.5–4 in), the maximum length recorded is 15.9 cm (6.3 in).

Distribution

They are found at depths of over 2,000 m (6,600 ft), and are found in all oceans.

Species

The fifteen known species are: * ''

Monognathus ahlstromi ''Monognathus ahlstromi'', the paddletail onejaw, is an ocean-dwelling eel found in the North Pacific Ocean off of the coast of the United States. It is found up to a depth of . It does not provide parental care. Little information is currently ...

Raju The Raju are a Telugu caste found mostly in the Indian state of Andhra Pradesh. Etymology and Early references ''Raju'' is a Telugu language variant of the Sanskrit title ''Raja'', a term for a monarch or princely ruler. Cynthia Talbot des ...

, 1974 (Paddletail onejaw) * '' Monognathus berteli'' J. G. Nielsen & Hartel, 1996. * '' Monognathus bertini'' Bertelsen & J. G. Nielsen, 1987. * '' Monognathus boehlkei'' Bertelsen & J. G. Nielsen, 1987. * '' Monognathus bruuni''

Bertin Bertin (; 615 – ''c''. 709 AD), also known as Saint Bertin the Great, was the Frankish abbot of a monastery in Saint-Omer later named the Abbey of Saint Bertin after him. He is venerated as a saint by the Catholic and Orthodox Churches. The ...

, 1936. * '' Monognathus herringi'' Bertelsen & J. G. Nielsen, 1987. * '' Monognathus isaacsi'' Raju, 1974. * '' Monognathus jesperseni'' Bertin, 1936. * '' Monognathus jesse'' Raju, 1974. * '' Monognathus nigeli'' Bertelsen & J. G. Nielsen, 1987. * '' Monognathus ozawai'' Bertelsen & J. G. Nielsen, 1987. * ''

Monognathus rajui ''Monognathus'', or onejaw, is the monotypic, only genus of the family Monognathidae of deep-sea eels. The name comes from the Greek language, Greek ''monos'' meaning "one" and ''gnathos'' meaning "jaw", a reference to the large mouth in comparis ...

'' Bertelsen & J. G. Nielsen, 1987. * '' Monognathus rosenblatti'' Bertelsen & J. G. Nielsen, 1987. * '' Monognathus smithi'' Bertelsen & J. G. Nielsen, 1987. * '' Monognathus taningi'' Bertin, 1936.

References

Monognathidae Deep sea fish Marine fish genera Taxa named by Léon Bertin {{Saccopharyngiformes-stub