Monognathus

Monognathus, or onejaw, is the only genus of the family Monognathidae of deep-sea eels. The name comes from the Greek 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 and premaxilla bones are absent).^[3]

Monognathus
M. jesperseni
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Anguilliformes
Suborder:	Anguilloidei
Family:	Monognathidae Trewavas, 1937[1]
Genus:	Monognathus Bertin, 1936
Species
15, see text.
Synonyms[2]
Phasmatostoma Myers, 1940

Description

The dorsal and anal fins lack bony supports and the pectoral fins are missing. The snout has a fang connected to glands, which are venomous in adults.^[4] 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.^[3]

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.^[5][3]

Species

The fifteen known species are:^[5]

• Monognathus ahlstromi Raju, 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, 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 Bertelsen & J. G. Nielsen, 1987.
• Monognathus rosenblatti Bertelsen & J. G. Nielsen, 1987.
• Monognathus smithi Bertelsen & J. G. Nielsen, 1987.
• Monognathus taningi Bertin, 1936.