The apron ray (''Discopyge tschudii'') is a small

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 ...

in the numbfish family, Narcinidae, known for being able to generate electric shocks for defense. It is one of two species in the genus ''Discopyge''.

Distribution and habitat

The apron ray is a coldwater marine species found off

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sout ...

south of the 33°S

parallel Parallel is a geometric term of location which may refer to: Computing * Parallel algorithm * Parallel computing * Parallel metaheuristic * Parallel (software), a UNIX utility for running programs in parallel * Parallel Sysplex, a cluster of ...

. It occurs in the southwest

Atlantic Ocean The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...

along the coasts of

Uruguay Uruguay (; ), officially the Oriental Republic of Uruguay ( es, República Oriental del Uruguay), is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast; while bordering ...

and

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

, with small numbers entering southern

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

in the winter, and in the southeast

Pacific Ocean 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 definition, to Antarctica) in the south, and is bounded by the contin ...

along the coasts of

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...

and

Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = National seal , national_motto = "Firm and Happy f ...

. The Atlantic and Pacific subpopulations are assumed to be separate, as the Atlantic subpopulation does not occur south of northern Argentina. The depths where it can be found range from . It lives on the continental shelf and prefers sandy substrate.

Description

In form, the apron ray resembles the genus '' Narcine'' in having a circular

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 ...

disc, two dorsal fins, and a stout tail with lateral folds. Its distinguishing feature is its pelvic fins, which are merged beneath the tail to form a continuous disc. The maximum length reported for the apron ray is a male; the females attain maturity at and the males at .

Biology

Apron rays are bottom-dwelling fish that are reported to be gregarious in nature. An analysis of stomach contents conducted by Arrighetti et al. (2005) showed that the primary food item in some 90% of apron rays are the siphon tips of the bivalve '' Amiantis purpurata''. The sizes of the

clam Clam is a common name for several kinds of bivalve molluscs. The word is often applied only to those that are edible and live as infauna, spending most of their lives halfway buried in the sand of the seafloor or riverbeds. Clams have two shel ...

s "grazed" in this way fell into small and large categories, corresponding to small and large rays, with males nipping longer pieces of siphon than the females. Another source gives the main diet of this species as

polychaete worm Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made ...

s and

gammarid Gammaridae is a family of amphipods. In North America they are included among the folk taxonomic category of " scuds", and otherwise gammarids is usually used as a common name. They have a wide distribution, centered on Eurasia, and are euryha ...

amphipods. The apron ray is

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 ...

; litters range from 1-12 pups but 4-5 are the most common. The pups measure long.

Conservation

The apron ray is caught infrequently as a

by-catch Bycatch (or by-catch), in the fishing industry, is a fish or other marine species that is caught unintentionally while fishing for specific species or sizes of wildlife. Bycatch is either the wrong species, the wrong sex, or is undersized or juve ...

bottom trawl Bottom trawling is trawling (towing a trawl, which is a fishing net) along the seafloor. It is also referred to as "dragging". The scientific community divides bottom trawling into benthic trawling and demersal trawling. Benthic trawling is tow ...

fisheries; it is of low commercial value and is discarded or used for fish meal. Research trawling conducted off Buenos Aires Province and

documented an 88% decline in this species from 1994-1999. However, the distribution of the species underwent a shift during this time, so it is unclear whether the decline could be attributed to the dramatic increase of unregulated commercial fishing in the region. Globally, the species is considered least concern. Along with other electric rays, the apron ray is important to

neuroscience Neuroscience is the scientific study of the nervous system (the brain, spinal cord, and peripheral nervous system), its functions and disorders. It is a multidisciplinary science that combines physiology, anatomy, molecular biology, developme ...

in the study of

cholinergic Cholinergic agents are compounds which mimic the action of acetylcholine and/or butyrylcholine. In general, the word " choline" describes the various quaternary ammonium salts containing the ''N'',''N'',''N''-trimethylethanolammonium cati ...

synaptic transmissions, due to the high concentration of

acetylcholine receptor An acetylcholine receptor (abbreviated AChR) is an integral membrane protein that responds to the binding of acetylcholine, a neurotransmitter. Classification Like other transmembrane receptors, acetylcholine receptors are classified according ...

and acetylcholinesterase in the cells of their

electric organ An electric organ, also known as electronic organ, is an electronic keyboard instrument which was derived from the pump organ, harmonium, pipe organ and theatre organ. Originally designed to imitate their sound, or orchestral sounds, it has sinc ...

References

{{DEFAULTSORT:ray, apron apron ray Fish of Chile Fish of Argentina Western South American coastal fauna Southeastern South American coastal fauna apron ray