Monognathus

Monognathidae
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Saccopharyngiformes
Suborder:	Saccopharyngoidei
Family:	Monognathidae
Genus:	Monognathus Bertin, 1936
Species
15, see text.

Monognathus, or onejaw, is the only genus of the family Monognathidae of deep-sea, eel-like fishes. 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). The dorsal and anal fins lack bony supports, the pectoral fins are missing. The snout has a fang which is connected to glands.

Typical lengths are from 4 to 10 cm (1.5–4 in), the maximum length recorded is 15.9 cm (6.3 in).

They are generally black in color, and are found at depths of over 2,000 m (6,600 ft).

Species

The fifteen known species are:

• 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.