''Oplegnathus'' is currently the sole recognized genus in the knifejaw family (Oplegnathidae) of marine

centrarchiform Centrarchiformes is an order of ray-finned fish, previously included amongst the perciformes. Froese, R. and D. Pauly. Editors. (2023). FishBase. Centrarchiformes. Accessed through: World Register of Marine Species at: https://www.marinespecies. ...

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. The largest, the Cape knifejaw, can reach a maximum length around 90 cm (35 in). Knifejaws have teeth fused into a parrot-like beak in adulthood. They feed on barnacles and mollusks, and are fished commercially. They are native to the Indian and

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is bounded by the cont ...

Oceans. The earliest records of knifejaws are fossilized beaks, with attached teeth, known from middle

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

-aged sediments of the

La Meseta Formation The La Meseta Formation is a sedimentary sequence deposited during much of the Paleogene on Seymour Island off the coast of the Antarctic Peninsula. It is noted for its fossils, which include both marine organisms and the only terrestrial vertebr ...

of Antarctica. Their early occurrence in Antarctica supports it having temperate climate during the Eocene, and that knifejaws had a wider distribution in the past than today.

Species

The currently recognized species in this genus are: * '' Oplegnathus conwayi'' J. Richardson, 1840, 1840 (Cape knifejaw) * '' Oplegnathus fasciatus'' (

Temminck Coenraad Jacob Temminck (; 31 March 1778 – 30 January 1858) was a Dutch patrician, zoologist and museum director. Biography Coenraad Jacob Temminck was born on 31 March 1778 in Amsterdam in the Dutch Republic. From his father, Jacob ...

& Schlegel, 1844) (

barred knifejaw The barred knifejaw (''Oplegnathus fasciatus''), also known as the striped beakfish or rock bream, is a species of marine ray-finned fish, from the Family (biology), family Oplegnathidae. It is commonly native to the north-western Pacific Ocean, ...

or striped beakfish) * ''

Oplegnathus insignis ''Oplegnathus'' is currently the sole recognized genus in the knifejaw family (Oplegnathidae) of marine centrarchiform ray-finned fishes. The largest, the Cape knifejaw, can reach a maximum length around 90 cm (35 in). Knifejaws have ...

'' ( Kner, 1867) (Pacific beakfish) * '' Oplegnathus peaolopesi''

J. L. B. Smith James Leonard Brierley Smith (26 September 1897 – 8 January 1968) was a South African ichthyology, ichthyologist, organic chemist, and university professor. He was the first to identify a taxidermied fish as a coelacanth, at the time thought t ...

, 1947 (Mozambique knifejaw) * '' Oplegnathus punctatus'' (

& Schlegel, 1844) (spotted knifejaw) * ''

Oplegnathus robinsoni ''Oplegnathus robinsoni'', the Natal knifejaw, or also commonly known as Cuckoo Bass and Natalse Kraaibek, is a ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish ...

'' Regan, 1916 (Natal knifejaw) * ''

Oplegnathus woodwardi ''Oplegnathus'' is currently the sole recognized genus in the knifejaw family (Oplegnathidae) of marine centrarchiform ray-finned fishes. The largest, the Cape knifejaw, can reach a maximum length around 90 cm (35 in). Knifejaws have ...

'' Waite, 1900 (knifejaw)

References

{{Centrarchiformes-stub Extant Eocene first appearances