Japanese narc [1] ( lat. Narke japonica ) - a species of stingrays of the genus Narci family lat. Narkidae squad of electric stingrays . These are cartilaginous fish, leading a bottom lifestyle, with large, flattened pectoral and abdominal fins, forming an almost round disc, a short, thick tail, ending in a muscular caudal fin and one dorsal fin. They are able to generate electric current. They live in temperate and subtropical waters of the northwestern part of the Pacific Ocean at a depth of 23 m. The maximum recorded length is 40 cm. Coloring from reddish-brown to chocolate. These stingrays reproduce by oviposition [2] [3] .
| Japanese narc |
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| Scientific classification |
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| No rank : | Bilateral symmetrical |
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| International scientific name |
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Narke japonica ( Temminck & Schlegel , 1850) |
| Synonyms |
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- Torpedo japonica Temminck & Schlegel, 1850
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| Area |
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| Security status |
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Vulnerable speciesIUCN 3.1 Vulnerable : 161665 |
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Japanese narcotics were known to science from the second quarter of the 19th century, when the German naturalists Philip Franz von Siebold and Heinrich Burger collected 4 samples of a new species, from which they made stuffed animals and placed them in the National Museum of Natural History in Leiden . 3 samples were named Narcine spec. and the fourth is Narcine timlei [4] . Based on the collected material, Konrad Jacob Temmink and German Schlegel published a description of the new species in a series of monographs devoted to the Japanese fauna [5] . Scientists attributed it to the subgenus Astrape of the genus Gnus . Later, this subgenus was recognized as a synonym for the genus Narok. In 1947, Marinus Boyzman re-examined the primary samples and assigned the largest of them, having a length of 27 cm, the lectotype of the species [4] . Some taxonomists consider the Japanese narcotics to be a conspecific red carpet based on their almost complete morphological identity [6] .
Japanese narcotics live in the northwestern Pacific. Their range extends from the south of Japan and Korea to the southern coast of China and Taiwan . These slopes are found on the continental shelf near the sandy bottom, often near rocky reefs [2] . In the waters of the Izu Peninsula, they occur at a depth of 12-23 m [7] .
The pectoral fins, whose width exceeds the length, form an almost round disc. On both sides of the head, electrical paired organs in the form of kidneys are visible through the skin. Small eyes protrude above the surface of the body. Immediately behind the eyes are large spatter with smooth raised edges. Small nostrils are located quite close to each other. Between them there is a leather flap covering the mouth. The protruding mouth forms a short straight line surrounded by a deep groove. Small teeth have an oval base and a pointed apex. Five pairs of gill slits [3] [8] are located on the lower side of the disk.
The edges of the large and wide ventral fins are arched, the base of the fins lies under the pectoral fins. Adult males have thick and short pterygopodia that are hidden under the ventral fins. Above the ventral fins is the only dorsal fin with rounded tips. There are folds of skin on the sides of the short and thick tail, the tail ends with a large triangular caudal fin, the upper and lower lobes of which are almost symmetrical. Soft skin is devoid of scales. The dorsal surface is reddish brown to dull brown; the back is sometimes covered with a few spots. The ventral surface is light brown. The maximum recorded length is 40 cm [3] [8] [7] .
Japanese narcotics are benthic marine fish. In general, they are inactive and spend most of their time motionless at the bottom, buried in the ground. They are capable of delivering an electric shock of 30β80 volts, defending themselves from predators, for example, from Cephaloscyllium umbratile [7] . Their electrical organs are composed of electrocytes, specialized cells derived from muscle fibers and filled with a jelly-like substance. These electrocytes are arranged in vertical columns forming electric organs that function like batteries with a parallel connection [9] . The diet of Japanese narok consists of bottom invertebrates . Tape worms Discobothrium japonicum parasitize on these slopes [10] .
Japanese narcotics breed by oviposition, like other electric stingrays. Litter of up to 5 newborns with a length of about 10 cm. They are colored lighter compared to adult stingrays. Males and females reach puberty with a length of 23β37 cm and 35 cm, respectively [3] .
Japanese sharks are hunted by
Cephaloscyllium umbratile sharks.
Japanese narcotics are capable of delivering a painful, but non-hazardous to human life, electric shock. They get along badly in captivity. Like other electric rays, they are used in biomedical research, since their electric organs contain many ion channels and acetylcholine receptors and can serve as a model of the human nervous system.
These ramps are not of interest for commercial fishing. They are sometimes caught as by- catch in the trawl shrimp fishery. Caught fish are usually thrown overboard, but their survival rate is low. The International Union for Conservation of Nature has assigned this species the status of βVulnerableβ [2] .
