Narcinidae, or numbfishes, are a family of

electric ray The electric rays are a group of rays, flattened cartilaginous fish with enlarged pectoral fins, composing the order Torpediniformes . They are known for being capable of producing an electric discharge, ranging from 8 to 220 volts, depending ...

s (order

Torpediniformes Fernando de Buen y Lozano was a Spanish ichthyologist and oceanographer Oceanography (), also known as oceanology and ocean science, is the scientific study of the oceans. It is an Earth science, which covers a wide range of topics, including ...

). They are bottom-dwelling cartilaginous fishes with large, rounded

pectoral fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...

discs and long tails. They can produce an

electric discharge An electric discharge is the release and transmission of electricity in an applied electric field through a medium such as a gas (ie., an outgoing flow of electric current through a non-metal medium).American Geophysical Union, National Research C ...

for defense, from which their scientific name is derived (

Greek Greek may refer to: Greece 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 ...

, meaning 'paralysis'). Members of this family are commonly known as the numbfishes, and are found almost worldwide in warm temperate and tropical continental and continental insular waters. They are strictly marine, so are absent from

river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of w ...

s and

lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much large ...

s. They occur in

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class o ...

beach A beach is a landform alongside a body of water which consists of loose particles. The particles composing a beach are typically made from rock, such as sand, gravel, shingle, pebbles, etc., or biological sources, such as mollusc sh ...

es, muddy enclosed bays,

estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environmen ...

, off

coral reef A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups. C ...

s and river mouths, and on the upper

continental slope A continental margin is the outer edge of continental crust abutting oceanic crust under coastal waters. It is one of the three major zones of the ocean floor, the other two being deep-ocean basins and mid-ocean ridges. The continental margin ...

to a depth of 1,071 m.Compagno, L.J.V. and Last, P.R. (1999). Narcinidae. Numbfishes. p. 1433-1437. In: K.E. Carpenter and V.H. Niem (eds.) ''FAO identification guide for fishery purposes. The living marine resources of the Western Central Pacific.'' Rome:

Food and Agriculture Organization The Food and Agriculture Organization of the United Nations (FAO)french: link=no, Organisation des Nations unies pour l'alimentation et l'agriculture; it, Organizzazione delle Nazioni Unite per l'Alimentazione e l'Agricoltura is an intern ...

Description

Small to medium-sized

rays Ray may refer to: Fish * Ray (fish), any cartilaginous fish of the superorder Batoidea * Ray (fish fin anatomy), a bony or horny spine on a fin Science and mathematics * Ray (geometry), half of a line proceeding from an initial point * Ray (gra ...

, adult numbfishes range from 15 to 66 cm long, though most are less than 50 cm. They have oval, rounded, or

shovel A shovel is a tool used for digging, lifting, and moving bulk materials, such as soil, coal, gravel, snow, sand, or ore. Most shovels are hand tools consisting of a broad blade fixed to a medium-length handle. Shovel blades are usually made o ...

-shaped pectoral discs and stout tails of equal or longer length. The snout is moderately elongated, rounded, or rounded-angular, differing from the narkids in being supported by broad rostral cartilages. The mouth is straight, with stout, elongated, and highly protrusible jaws and a prominent groove around its periphery. The

nostril A nostril (or naris , plural ''nares'' ) is either of the two orifices of the nose. They enable the entry and exit of air and other gasses through the nasal cavities. In birds and mammals, they contain branched bones or cartilages called turbi ...

s are just forward of the mouth and connected to it by a broad groove; the nasal flaps are short, but merged into a broad nasal curtain that overlaps the mouth. The small teeth have a single moderate cusp; the teeth and tooth bands are exposed when the mouth is closed (except in ''Diplobatis''). Two prominent

dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through c ...

s of roughly equal size and a large

caudal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...

are present. Numbfishes vary in color from whitish or yellowish to brownish, grey-brown, greenish, reddish, or black above, either plain or with small to large spots, blotches, bars or lines, sometimes forming complex eye-shaped spots or

ocelli A simple eye (sometimes called a pigment pit) refers to a form of eye or an optical arrangement composed of a single lens and without an elaborate retina such as occurs in most vertebrates. In this sense "simple eye" is distinct from a multi-l ...

on the pectoral fins. They are usually white underneath, or black in deep-water species. The large,

kidney The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blo ...

-shaped electric organs at the base of the pectoral fins are visible through the skin.

Biology and ecology

Numbfishes are slow-swimming bottom-dwellers that feed on small

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of ...

es and

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

s off the bottom; their protrusible jaws aid in removing prey from the substrate. They can generate a moderate shock if disturbed and contact is made with the electric organs; the electrical discharges of narcinids have been measured at 8-37

volt The volt (symbol: V) is the unit of electric potential, electric potential difference (voltage), and electromotive force in the International System of Units (SI). It is named after the Italian physicist Alessandro Volta (1745–1827). Defin ...

s, much less than the electric rays of the genus ''

Torpedo A modern torpedo is an underwater ranged weapon launched above or below the water surface, self-propelled towards a target, and with an explosive warhead designed to detonate either on contact with or in proximity to the target. Historically, s ...

''.Martin, R. Aidan
Electric Rays
''ReefQuest Centre for Shark Research.'' Retrieved on October 12, 2008. All species are

ovoviviparous Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a term used as a "bridging" form of reproduction between egg-laying oviparous and live-bearing viviparous reproduction. Ovoviviparous animals possess embryos that develop insi ...

, with eggs hatching inside the mother.

Genera

These genera are included in this family: * '' Benthobatis'' * '' Diplobatis'' * ''

Discopyge ''Discopyge'' is a small genus of fish, the apron rays, in the family Narcinidae. Species * '' Discopyge castelloi'' Menni, Rincón & M. L. Garcia, 2008 * '' Discopyge tschudii'' Heckel, 1846 (Apron ray) References Narcinidae Ray gen ...

'' * '' Narcine'' * '' Narcinops''

References

{{Taxonbar, from=Q2167421 Torpediniformes Marine fish families Ray families Taxa named by Theodore Gill