Pitted stingray
Encyclopedia
The pitted stingray is a species
of stingray
in the family
Dasyatidae, endemic to the waters around Japan
and the Sea of Japan
. It typically found near the coast at depths of 40–60 m (131.2–196.9 ft), but may also venture into the open sea. Measuring up to 1.2 m (3.9 ft) across, the pitted stingray has a diamond-shaped pectoral fin disc with a characteristic "W"-shaped groove on the underside. Other identifying characteristics of this species include its dark gray dorsal coloration with small white spots, and the presence of dorsal tubercles in adults. Pitted stingrays are caught as bycatch
in coastal fisheries and brought to market. The International Union for Conservation of Nature (IUCN) does not yet have sufficient data to assess this species beyond Data Deficient
.
, Japan. Some authors regard the multispine giant stingray
(D. multispinosa) as the same as this species.
around Japan, and is particularly abundant around Hokkaidō
and northern Honshū
. It has also been recorded from elsewhere in the Sea of Japan, near South Korea
and Vladivostok
, Russia
. The pitted stingray is generally a bottom-dweller inhabiting coastal waters 40–60 m (131.2–196.9 ft) deep. However, the capture of one individual near the surface over water 3000 m (9,842.5 ft) deep in the Sea of Japan suggests that this species may have pelagic habits as well.
e to 12, arranged in three rows of 3, 7 and 2. There are 34–44 upper tooth rows and 33–46 lower tooth rows. There is a distinctive "W"-shaped furrow on the underside of the disc, at the center behind the fifth pair of gill slit
s. Only one other member of its family, the groovebelly stingray
(D. hypostigma), shares this feature.
The tail is whip-like and measures 75–122% of the disc width, bearing 1–3 stinging spines on the upper surface. The tail spine averages 6.5 cm (2.6 in) long with 90 serrations in males, and 7.7 cm (3 in) long with 87 serrations in females. Behind the spine, there is a low dorsal keel and a ventral fin fold measuring less than half as long as the disc width. Mature individuals have a row of 2–10 tubercles on the snout tip, 3–5 tubercles on the back, and 1–8 tubercles before the spine. The tail is covered by dermal denticles towards the tip. This species is dark gray above, darkening on the tail fold, and white below with gray irregular spots and fin margins. The upper surface of the disc bears many small pores that are ringed in white. The pitted stingray attains a disc width of 1.2 m (3.9 ft).
e of gnathiid
isopods, which attach to the gill
s. Reproduction is presumably aplacental viviparous like other stingrays.
by Japanese coastal fisheries, using longlines, gillnet
s, and set nets
, and marketed for human consumption. However, the significance of this species in catches relative to other stingray species is unknown. As a result, the International Union for Conservation of Nature (IUCN) has listed it as Data Deficient
.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of stingray
Myliobatiformes
Myliobatiformes is one of the four orders of batoids, cartilaginous fishes related to sharks. They were formerly included in the order Rajiformes, but more recent phylogenetic studies have shown that the myliobatiforms are a monophyletic group, and that its more derived members evolved their...
in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Dasyatidae, endemic to the waters around Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
and the Sea of Japan
Sea of Japan
The Sea of Japan is a marginal sea of the western Pacific Ocean, between the Asian mainland, the Japanese archipelago and Sakhalin. It is bordered by Japan, North Korea, Russia and South Korea. Like the Mediterranean Sea, it has almost no tides due to its nearly complete enclosure from the Pacific...
. It typically found near the coast at depths of 40–60 m (131.2–196.9 ft), but may also venture into the open sea. Measuring up to 1.2 m (3.9 ft) across, the pitted stingray has a diamond-shaped pectoral fin disc with a characteristic "W"-shaped groove on the underside. Other identifying characteristics of this species include its dark gray dorsal coloration with small white spots, and the presence of dorsal tubercles in adults. Pitted stingrays are caught as bycatch
Bycatch
The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...
in coastal fisheries and brought to market. The International Union for Conservation of Nature (IUCN) does not yet have sufficient data to assess this species beyond Data Deficient
Data Deficient
Data Deficient is a category applied by the IUCN, other agencies, and individuals to a species when the available information is not sufficient for a proper assessment of conservation status to be made...
.
Taxonomy
Japanese ichthyologist Yasunori Miyosi described the pitted stingray in a 1939 issue of the Bulletin of the Biogeographical Society of Japan, based on a specimen collected from the Hyuga-nada Sea in eastern Miyazaki PrefectureMiyazaki Prefecture
is a prefecture of Japan located on the island of Kyushu. The capital is the city of Miyazaki.- History :Historically, after the Meiji Restoration, Hyūga Province was renamed Miyazaki Prefecture....
, Japan. Some authors regard the multispine giant stingray
Multispine giant stingray
The multispine giant stingray, Dasyatis multispinosa is a species of stingray in the family Dasyatidae. Some authors regard this species as the same as the pitted stingray ....
(D. multispinosa) as the same as this species.
Distribution and habitat
The pitted stingray is found over the continental shelfContinental shelf
The continental shelf is the extended perimeter of each continent and associated coastal plain. Much of the shelf was exposed during glacial periods, but is now submerged under relatively shallow seas and gulfs, and was similarly submerged during other interglacial periods. The continental margin,...
around Japan, and is particularly abundant around Hokkaidō
Hokkaido
, formerly known as Ezo, Yezo, Yeso, or Yesso, is Japan's second largest island; it is also the largest and northernmost of Japan's 47 prefectural-level subdivisions. The Tsugaru Strait separates Hokkaido from Honshu, although the two islands are connected by the underwater railway Seikan Tunnel...
and northern Honshū
Honshu
is the largest island of Japan. The nation's main island, it is south of Hokkaido across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyushu across the Kanmon Strait...
. It has also been recorded from elsewhere in the Sea of Japan, near South Korea
South Korea
The Republic of Korea , , is a sovereign state in East Asia, located on the southern portion of the Korean Peninsula. It is neighbored by the People's Republic of China to the west, Japan to the east, North Korea to the north, and the East China Sea and Republic of China to the south...
and Vladivostok
Vladivostok
The city is located in the southern extremity of Muravyov-Amursky Peninsula, which is about 30 km long and approximately 12 km wide.The highest point is Mount Kholodilnik, the height of which is 257 m...
, Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
. The pitted stingray is generally a bottom-dweller inhabiting coastal waters 40–60 m (131.2–196.9 ft) deep. However, the capture of one individual near the surface over water 3000 m (9,842.5 ft) deep in the Sea of Japan suggests that this species may have pelagic habits as well.
Description
The pitted stingray has a diamond-shaped pectoral fin disc wider than long, with almost straight leading margins converging to the tip of the snout at a blunt angle, and rounded trailing margins. The floor of the mouth contains anywhere from zero papillaPapilla (fish mouth structure)
The papilla, in certain kinds of fish, particularly rays, sharks, and catfish, are small lumps of dermal tissue found in the mouth, where they are "distributed uniformly on the tongue, palate, and pharynx"...
e to 12, arranged in three rows of 3, 7 and 2. There are 34–44 upper tooth rows and 33–46 lower tooth rows. There is a distinctive "W"-shaped furrow on the underside of the disc, at the center behind the fifth pair of gill slit
Gill slit
Gill slits are individual openings to gills, i.e., multiple gill arches, which lack a single outer cover. Such gills are characteristic of Cartilaginous fish such as sharks, rays, sawfish, and guitarfish. Most of these have five pairs, but a few species have 6 or 7 pairs...
s. Only one other member of its family, the groovebelly stingray
Groovebelly stingray
The groovebelly stingray, Dasyatis hypostigma, called the butter stingray by fishery workers, is a species of stingray in the family Dasyatidae. It is found over sandy or muddy bottoms in shallow coastal waters off southern Brazil, and probably Uruguay and Argentina...
(D. hypostigma), shares this feature.
The tail is whip-like and measures 75–122% of the disc width, bearing 1–3 stinging spines on the upper surface. The tail spine averages 6.5 cm (2.6 in) long with 90 serrations in males, and 7.7 cm (3 in) long with 87 serrations in females. Behind the spine, there is a low dorsal keel and a ventral fin fold measuring less than half as long as the disc width. Mature individuals have a row of 2–10 tubercles on the snout tip, 3–5 tubercles on the back, and 1–8 tubercles before the spine. The tail is covered by dermal denticles towards the tip. This species is dark gray above, darkening on the tail fold, and white below with gray irregular spots and fin margins. The upper surface of the disc bears many small pores that are ringed in white. The pitted stingray attains a disc width of 1.2 m (3.9 ft).
Biology and ecology
Little is known of the natural history of the pitted stingray. This species is parasitized by the praniza larvaLarva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e of gnathiid
Gnathiidae
Gnathiidae is a family of isopod crustaceans. They occur in a wide range of depths, from the littoral zone to the deep sea. The adults are associated with sponges and may not feed...
isopods, which attach to the gill
Gill
A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist...
s. Reproduction is presumably aplacental viviparous like other stingrays.
Human interactions
The pitted stingray is caught incidentallyBycatch
The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...
by Japanese coastal fisheries, using longlines, gillnet
Gillnet
Gillnetting is a common fishing method used by commercial and artisanal fishermen of all the oceans and in some freshwater and estuary areas. The gillnet also is used by fisheries scientists to monitor fish populations. Because gillnets can be so effective their use is closely monitored and...
s, and set nets
Fishing net
A fishing net or fishnet is a net that is used for fishing. Fishing nets are meshes usually formed by knotting a relatively thin thread. Modern nets are usually made of artificial polyamides like nylon, although nets of organic polyamides such as wool or silk thread were common until recently and...
, and marketed for human consumption. However, the significance of this species in catches relative to other stingray species is unknown. As a result, the International Union for Conservation of Nature (IUCN) has listed it as Data Deficient
Data Deficient
Data Deficient is a category applied by the IUCN, other agencies, and individuals to a species when the available information is not sufficient for a proper assessment of conservation status to be made...
.