The Gonorynchiformes are an order of

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 ...

that includes the important food source, the milkfish (''Chanos chanos'', family Chanidae), and a number of lesser-known types, both marine and

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

. The alternate spelling "Gonorhynchiformes", with an "h", is frequently seen but not official. Gonorynchiformes have small mouths and no teeth. They are the sole group in the clade Anotophysi, a subgroup of the superorder Ostariophysi. They are characterized by a primitive Weberian apparatus formed by the first three vertebrae and one or more cephalic ribs within the head. This apparatus is believed to be a hearing organ, and is found in a more advanced and complex form in the related cypriniform fish, such as

carp The term carp (: carp) is a generic common name for numerous species of freshwater fish from the family (biology), family Cyprinidae, a very large clade of ray-finned fish mostly native to Eurasia. While carp are prized game fish, quarries and a ...

. Also like the cypriniforms, the gonorynchiforms produce a substance from their skin when injured that dissolves into the water and acts an alarm signal to other fish.

Taxonomy

Although many of the families are rather small, there are several fossil genera. This listing of the groups of Gonorynchiformes includes fossil fish with a short description. They are listed in approximate order of how primitive their characteristics are. The 5th edition of ''

Fishes of the World ''Fishes of the World'' is a standard reference for the systematics of fishes. It was first written in 1976 by the American ichthyologist Joseph S. Nelson (1937–2011). Now in its fifth edition (2016), the work is a comprehensive overview of t ...

'' classifies the extant taxa in this order as follows, as does '' Eschmeyer's Catalog of Fishes'': Order Gonorynchiformes Greenwood, Rosen, Weitzman, and Myers, 1966 * Family Chanidae Günther, 1868 (milkfishes) * Family Gonorynchidae Richardson, 1848 (beaked sandfishes) * Family Kneriidae Günther, 1868 (shellears) * Family Phractolaemidae Boulenger, 1901 (snake mudheads)

References

Bibliography

* {{Authority control Extant Berriasian first appearances Ray-finned fish orders Taxa named by George S. Myers Taxa named by Humphry Greenwood Taxa named by Donn Eric Rosen