Apron ray | |
---|---|
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Chondrichthyes |
Superorder: | Batoidea |
Order: | Torpediniformes |
Family: | Narcinidae |
Genus: | Discopyge |
Species: | D. tschudii |
Binomial name | |
Discopyge tschudii | |
Synonyms | |
Torpedo chilensisGuichenot, 1848 |
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The apron ray (Discopyge tschudii) is a small electric ray 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. [2]
The apron ray is a coldwater marine species found off South America south of the 33°S parallel. It occurs in the southwest Atlantic Ocean along the coasts of Uruguay and Argentina, with small numbers entering southern Brazil in the winter, and in the southeast Pacific Ocean along the coasts of Chile and Peru. 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 22–181 metres (72–594 ft). [1] It lives on the continental shelf and prefers sandy substrate. [3]
In form, the apron ray resembles the genus Narcine in having a circular pectoral fin 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. [4] The maximum length reported for the apron ray is a 54 centimetres (21 in) male; the females attain maturity at 27.5 centimetres (10.8 in) and the males at 35–46 centimetres (14–18 in). [1]
Apron rays are bottom-dwelling fish that are reported to be gregarious in nature. [3] 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 clams "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. [5] Another source gives the main diet of this species as polychaete worms and gammarid amphipods. The apron ray is ovoviviparous; litters range from 1-12 pups but 4-5 are the most common. The pups measure 8.5–9.2 centimetres (3.3–3.6 in) long. [1]
The apron ray is caught infrequently as a by-catch of bottom trawl fisheries; it is of low commercial value and is discarded or used for fish meal. Research trawling conducted off Buenos Aires Province and Uruguay 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. [1]
Along with other electric rays, the apron ray is important to neuroscience in the study of cholinergic synaptic transmissions, due to the high concentration of acetylcholine receptor and acetylcholinesterase in the cells of their electric organs. [3]
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 on species, used to stun prey and for defense. There are 69 species in four families.
Typhlonarke is a genus of sleeper ray in the family Narkidae, containing two poorly known species. The group is known for producing electric shocks for defense. Both species are deep-sea rays endemic to the waters off New Zealand. They are not to be confused with the blind electric rays of the genus Benthobatis.
Tetronarce californica also known as the Pacific electric ray is a species of electric ray in the family Torpedinidae, endemic to the coastal waters of the northeastern Pacific Ocean from Baja California to British Columbia. It generally inhabits sandy flats, rocky reefs, and kelp forests from the surface to a depth of 200 m (660 ft), but has also been known to make forays into the open ocean. Measuring up to 1.4 m (4.6 ft) long, this species has smooth-rimmed spiracles and a dark gray, slate, or brown dorsal coloration, sometimes with dark spots. Its body form is typical of the genus, with a rounded pectoral fin disc wider than long and a thick tail bearing two dorsal fins of unequal size and a well-developed caudal fin.
The oval electric ray is a little-known species of sleeper ray in the family Narkidae. It is endemic to New Zealand, where it is generally found on the sea floor at a depth of 300–400 m (980–1,310 ft). Seldom exceeding 30 cm (12 in) in length, this species has a thick, oval pectoral fin disc and a short, stout tail with a single dorsal fin. It is blind, as its tiny eyes are covered by skin. Its pelvic fins are divided in two, with the anterior portion forming a limb-like appendage. These appendages likely allow the ray, which may not be able to swim at all, to "walk" along the bottom. The claspers of adult males extend beyond the disc. Polychaete worms are known to be part of its diet, and its reproduction is aplacental viviparous. It can produce an electric shock for defense. The International Union for Conservation of Nature presently lacks the data to assess its conservation status.
The round ribbontail ray or blotched fantail ray, is a species of stingray in the family Dasyatidae, found throughout the nearshore waters of the tropical Indo-Pacific, as well as off islands in the eastern Pacific. It is a bottom-dwelling inhabitant of lagoons, estuaries, and reefs, generally at a depth of 20–60 m (66–197 ft). Reaching 1.8 m (5.9 ft) across, this large ray is characterized by a thick, rounded pectoral fin disc covered by small tubercles on top, and a relatively short tail bearing a deep ventral fin fold. In addition, it has a variable but distinctive light and dark mottled pattern on its upper surface, and a black tail.
Squatina squatina, the angelshark or monkfish, is a species of shark in the family Squatinidae, that were once widespread in the coastal waters of the northeastern Atlantic Ocean. Well-adapted for camouflaging itself on the sea floor, the angelshark has a flattened form with enlarged pectoral and pelvic fins, giving it a superficial resemblance to a ray. This species can be identified by its broad and stout body, conical barbels, thornless back, and grayish or brownish dorsal coloration with a pattern of numerous small light and dark markings. It measures up to 2.4 m (7.9 ft) long.
Discopyge is a small genus of fish, the apron rays, in the family Narcinidae.
The ocellated electric ray or bullseye electric ray is a species of electric ray in the family Narcinidae, native to the shallow inshore waters of the eastern central Pacific from the Gulf of California to Ecuador. Reaching 25 cm (9.8 in) in length, this species has a rounded pectoral fin disc and pelvic fins with convex margins. Its short and thick tail bears two dorsal fins and terminates in a triangular caudal fin. The ocellated electric ray is named for the distinctive large eyespot on the middle of its disc, consisting of a black or yellow center surrounded by concentric rings. Its dorsal coloration is otherwise highly variable, ranging from plain to ornately patterned on a light to dark brown background. The front part of its disc is darker brown.
The marbled electric ray is a species of electric ray in the family Torpedinidae found in the coastal waters of the eastern Atlantic Ocean from the North Sea to South Africa. This benthic fish inhabits rocky reefs, seagrass beds, and sandy and muddy flats in shallow to moderately deep waters. It can survive in environments with very little dissolved oxygen, such as tidal pools. The marbled electric ray has a nearly circular pectoral fin disc and a muscular tail that bears two dorsal fins of nearly equal size and a large caudal fin. It can be identified by the long, finger-like projections on the rims of its spiracles, as well as by its dark brown mottled color pattern, though some individuals are plain-colored. Males and females typically reach 36–38 cm (14–15 in) and 55–61 cm (22–24 in) long respectively.
The crossback stingaree or banded stingaree is a species of stingray in the family Urolophidae. It is endemic to southeastern Australia, mainly off Victoria and Tasmania but also marginally to New South Wales and South Australia. This bottom-dwelling fish generally inhabits sand and reef habitats deeper than 100 m (330 ft) off Victoria, and muddy habitats in shallow bays and estuaries off Tasmania. Befitting its name, the crossback stingaree has a distinctive dark pattern on its back, consisting of a midline stripe that is crossed by three transverse bars. It has an oval pectoral fin disc with a blunt snout and a skirt-shaped curtain of skin between the nostrils. Its tail is short with no skin fold along the sides, and a deep, leaf-shaped caudal fin. The youngest rays may have a small dorsal fin in front of the stinging tail spine. This species reaches 50 cm (20 in) in length.
The sparsely spotted stingaree, also known as the white-spotted stingaree or Dixon's stingaree, is a species of stingray in the family Urolophidae, common off the southern Australian coast. Preferring sandy flats and seagrass beds, this benthic ray can be found from close to shore to a depth of at least 150 m (490 ft), and tends to occur deeper in the northern portion of its range. Reaching a length of 57 cm (22 in), this species has a broad, diamond-shaped pectoral fin disc that is typically plain gray in color above with a V-shaped marking between the eyes. Individuals from southerly waters also generally exhibit a smattering of small, dark-edged white spots. This ray is further characterized by a distinctively bell-shaped curtain of skin between the nostrils. Its tail has a skin fold running along either side and a leaf-shaped caudal fin, but no dorsal fin.
The Kapala stingaree is a species of stingray in the family Urolophidae, endemic to inshore waters off southeastern Queensland and New South Wales. It is commonly found on and around rocky reefs at a depth of 10–130 m (33–427 ft). Reaching 51 cm (20 in) in length, the Kapala stingaree has a rounded, diamond-shaped pectoral fin disc and a slender tail, which ends in a leaf-shaped caudal fin and bears lateral skin folds and a small dorsal fin in front of the stinging spine. It has a distinctive bell-shaped curtain of skin between its nostrils. This species is greenish above, with a highly variable pattern of dark markings usually found outside and between the eyes, and over the back and tail.
The spotted dragonet is a species of dragonet native to the eastern Atlantic Ocean and the Mediterranean Sea where it occurs at depths of from 45 to 650 metres. This species is important to local peoples engaged in subsistence fishing.
The blind electric ray is a little-known species of sleeper ray in the family Narkidae, endemic to New Zealand. It is found on the bottom, typically at a depth of 300–400 m (980–1,310 ft). Reaching 38 cm (15 in) in length, this species has a thin, nearly circular pectoral fin disc without visible eyes, and a short tail with a single dorsal fin. Its pelvic fins are divided in two, with the anterior portion forming a limb-like appendage; in males the claspers do not extend past the disc margin. A weak swimmer, the blind electric ray likely pushes itself along using its pelvic fins. It is known to feed on polychaete worms, and can defend itself with an electric shock. Reproduction is aplacental viviparous. The International Union for Conservation of Nature (IUCN) does not have enough information to assess the conservation status of this species.
Narcine brasiliensis, the Brazilian electric ray or lesser numbfish, is a species of electric ray in the family Narcinidae. It inhabits coastal waters of the Southwest Atlantic from Southern Brazil through Uruguay to northern Argentina.
The Japanese sleeper ray is a species of electric ray in the family Narkidae. It is common in the inshore and offshore waters of the northwestern Pacific Ocean from southern Japan to southern China. Growing up to 40 cm (16 in) long, the Japanese sleeper ray has a nearly circular pectoral fin disc colored reddish to chocolate brown above, sometimes with darker or lighter spots, and lighter brown below. The spiracles behind its small eyes have raised, smooth rims. Its short and muscular tail bears a single dorsal fin positioned aft of the rounded pelvic fins, and terminates in a large caudal fin.
Macrourus berglax, the roughhead grenadier or onion-eye grenadier, is a species of marine ray-finned fish in the family Macrouridae. It is a deep-water fish found in the Atlantic Ocean.
The onefin electric ray or Cape numbfish is a common but little-known species of electric ray in the family Narkidae, native to South Africa and Namibia. It is a benthic fish found in shallow coastal bays over sandy or muddy bottoms. This small species reaches 38 cm (15 in) in length, and has a nearly circular pectoral fin disc and a short, muscular tail that supports a large caudal fin. It can be identified by its single dorsal fin, which is located over the large pelvic fins. Its dorsal coloration is yellowish to dusky brown.
The Tasmanian numbfish is a species of electric ray in the family Narcinidae. Endemic to southeastern Australia, this common ray inhabits shallow continental shelf waters in the southern portion of its range and deeper continental slope waters in the northern portion of its range. It prefers sand and mud habitats. This species can be identified by its spade-shaped pectoral fin disc with concave anterior margins, long tail with well-developed skin folds along either side, and plain dark brown dorsal colouration. Its maximum known length is 47 cm (19 in).
The common eagle ray or bullray is a species of fish in the family Myliobatidae. It inhabits the eastern Atlantic Ocean, the Mediterranean Sea and the south-western Indian Ocean.