The Japanese sleeper ray (Narke japonica) 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 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. Inhabiting shallow, sandy areas near rocky reefs, the Japanese sleeper ray is a bottom-dwelling predator of invertebrates. Like other members of its family, it can produce a strong electric shock from its electric organs for defensive purposes. Females give live birth to litters of up to five pups. The gestating young are sustained at first by yolk, and later by histotroph ("uterine milk"). The International Union for Conservation of Nature (IUCN) has listed this species as Vulnerable, due to its susceptibility to trawl fisheries that operate intensively throughout its range. Taxonomy The first specimens of the Japanese sleeper ray known to science were four fish collected from Japan by German naturalists Philipp Franz von Siebold and Heinrich Burger during the second quarter of the 19th century. The specimens were stuffed and deposited at the National Museum of Natural History in Leiden; three of them were labeled as "Narcine spec." and one as "Narcine timlei". This material formed the basis for a description authored by Coenraad Jacob Temminck and Hermann Schlegel, which was published in 1850 as part of Fauna Japonica, a series of monographs on Japanese zoology. Temminck and Schlegel assigned the new species to the subgenus Astrape of the genus Torpedo; later authors would synonymize Astrape with Narke. In 1947, Marinus Boeseman reexamined the four original specimens and designated the largest, long, as the species lectotype. Other common names for this ray are Japanese electric ray and Japanese spotted torpedo. Some taxonomists believe that the sleeper torpedo (Crassinarke dormitor) may be conspecific with the Japanese sleeper ray, as their morphology is virtually identical. Description The Japanese sleeper ray has an almost circular pectoral fin disc wider than long. Two large, kidney-shaped electric organs are visible under the skin on either side of the head. The small, protruding eyes