The Yantai stingray, ''Hemitrygon laevigata'' (often misspelled ''laevigatus''), is a little-known

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

stingray Stingrays are a group of sea rays, which are cartilaginous fish related to sharks. They are classified in the suborder Myliobatoidei of the order Myliobatiformes and consist of eight families: Hexatrygonidae (sixgill stingray), Plesiobatidae ( ...

in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Dasyatidae, inhabiting shallow waters in the northwestern

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 continen ...

off the coasts of

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

and

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

. Measuring no more than across, this species is characterized by its diamond-shaped

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 wider than long, completely smooth skin, dorsal coloration of dark irregular spots on a yellowish gray-brown background, and ventral coloration of more spots on a white background with yellowish margins. One of the three most common stingrays sold for food in China, the slow-reproducing Yantai stingray faces possible

overfishing Overfishing is the removal of a species of fish (i.e. fishing) from a body of water at a rate greater than that the species can replenish its population naturally (i.e. the overexploitation of the fishery's existing fish stock), resulting in th ...

and

habitat degradation Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...

, and its numbers appear to be declining. The

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

(IUCN) has assessed it as vulnerable.

Taxonomy

The Yantai stingray was described by Yuanting Chu in his 1960 ''Cartilaginous Fishes of China'', based on specimens obtained from the

Shanghai Shanghai (; , , Standard Mandarin pronunciation: ) is one of the four direct-administered municipalities of the People's Republic of China (PRC). The city is located on the southern estuary of the Yangtze River, with the Huangpu River flow ...

Fish Market, Dongfushan, and Huaniao.Catalog of Fishes (Online Version)
California Academy of Sciences. Retrieved on January 8, 2010.

Distribution and habitat

The Yantai stingray is found in the

Yellow Sea The Yellow Sea is a marginal sea of the Western Pacific Ocean located between mainland China and the Korean Peninsula, and can be considered the northwestern part of the East China Sea. It is one of four seas named after common colour terms ...

and the

East China Sea The East China Sea is an arm of the Western Pacific Ocean, located directly offshore from East China. It covers an area of roughly . The sea’s northern extension between mainland China and the Korean Peninsula is the Yellow Sea, separated b ...

, as far north as

and as far south as the

Taiwan Strait The Taiwan Strait is a -wide strait separating the island of Taiwan and continental Asia. The strait is part of the South China Sea and connects to the East China Sea to the north. The narrowest part is wide. The Taiwan Strait is itself a s ...

; it is reportedly abundant off southern Japan and northern China. This bottom-dwelling species inhabits inshore waters to a depth of , and has been known to enter

estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environment ...

Description

A small species, male and female Yantai stingrays grow to no more than and across respectively. Its

disc is diamond-shaped and 1.2–1.3 times wider than long, with nearly straight anterior margins converging to a blunt-angled snout, and rounded outer margins. The large, protruding eyes are immediately followed by a pair of equal-sized or slightly smaller, elliptical

spiracle Spiracle or spiraculum may refer to: * Spiracle (arthropods), opening in the exoskeletons of some arthropods * Spiracle (vertebrates), openings on the surface of some vertebrates * Spiraculum, a genus of land snails in family Cyclophoridae Cycl ...

s. There is a flap of skin between the nares that reaches the mouth, with a straight and fringed rear margin. The mouth is small and bow-shaped, with three

papilla Papilla (Latin, 'nipple') or papillae may refer to: In animals * Papilla (fish anatomy), in the mouth of fish * Basilar papilla, a sensory organ of lizards, amphibians and fish * Dental papilla, in a developing tooth * Dermal papillae, part of ...

e across the floor. The teeth are arranged with a

quincunx A quincunx () is a geometric pattern consisting of five points arranged in a cross, with four of them forming a square or rectangle and a fifth at its center. The same pattern has other names, including "in saltire" or "in cross" in heraldry (dep ...

pattern into pavement-like surfaces; the teeth of adult males have a sharp recurved cusp, while those of females and juveniles are blunt. There are around 40 tooth rows in the upper jaw. The five pairs of

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 and rays, as well as deep-branching vertebrates such as lampreys. In con ...

s are short.Nishida, K. and K. Nakaya (1990). "Taxonomy of the genus ''Dasyatis'' (Elasmobranchii, Dasyatididae) from the North Pacific." in Pratt, H.L., S.H. Gruber and T. Taniuchi. ''Elasmobranchs as living resources: advances in the biology, ecology, systematics, and behaviour, and the status of fisheries.'' NOAA Technical Report, NMFS 90. pp. 327–346. The

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral surface of fish. The paired pelvic fins are homologous to the hindlimbs of tetrapods. Structure and function Structure In actinopterygians, the pelvic fin consists of two en ...

s are almost rectangular in shape, with those of females being wider and more strongly curved posteriorly than those of males. The tail measures 1.4–1.8 times the disc length and is laterally compressed, becoming whip-like towards the tip. The stinging tail spine measures about long and bears on average 60 serrations. Following the spine is a short, narrow dorsal fin fold and a wider ventral fin fold running along two-fifths of the tail. The skin is completely devoid of

dermal denticle A fish scale is a small rigid plate that grows out of the skin of a fish. The skin of most jawed fishes is covered with these protective scales, which can also provide effective camouflage through the use of reflection and colouration, as we ...

s even in adults. The disc is yellowish gray-brown above, with irregular darker blotches and yellow marks adjacent to the eyes and spiracles; the underside is white with irregular darker spots and a yellowish gray margin. The tail is dark brown with a yellow lateral stripe and black fin folds.

Biology and ecology

Little is known of the Yantai stingray's natural history. Like other stingrays, it is

aplacental viviparous 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 ...

with females probably giving birth to only 1–2 pups at a time.

Human interactions

Although generally innocuous towards humans, fishery workers have been injured by the

venom Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved ''venom apparatus'', such as fangs or a sti ...

ous tail spine of the Yantai stingray. Envenomation by this species causes intense pain and

edema Edema, also spelled oedema, and also known as fluid retention, dropsy, hydropsy and swelling, is the build-up of fluid in the body's Tissue (biology), tissue. Most commonly, the legs or arms are affected. Symptoms may include skin which feels t ...

, can lead to weakness,

nausea Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. While not painful, it can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the ...

arrhythmia Arrhythmias, also known as cardiac arrhythmias, heart arrhythmias, or dysrhythmias, are irregularities in the heartbeat, including when it is too fast or too slow. A resting heart rate that is too fast – above 100 beats per minute in adults ...

paresthesia Paresthesia is an abnormal sensation of the skin (tingling, pricking, chilling, burning, numbness) with no apparent physical cause. Paresthesia may be transient or chronic, and may have any of dozens of possible underlying causes. Paresthesias ar ...

, and

convulsion A convulsion is a medical condition where the body muscles contract and relax rapidly and repeatedly, resulting in uncontrolled shaking. Because epileptic seizures typically include convulsions, the term ''convulsion'' is sometimes used as a s ...

s, and may even be fatal. Yantai stingrays are taken by coastal benthic

commercial fisheries Commercial fishing is the activity of catching fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the world, but those who practice it as an industry must often ...

bycatch 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 ...

. In Japan, where it is often mistaken for the

red stingray The red stingray (''Hemitrygon akajei'') is a species of stingray in the family Dasyatidae, found in the northwestern Pacific Ocean off Japan, Korea, and China, and possibly elsewhere. It primarily inhabits shallow, sandy habitats close to shore ...

(''D. akajei''), its small size typically results in captured individuals being discarded. Such is not the case in China, where the Yantai stingray is one of the three most common stingrays brought to market. The

(IUCN) has listed the Yantai stingray as vulnerable, as with its slow reproductive rate its population is unlikely to withstand the intense fishing pressure present throughout both the Yellow and East China Seas. Furthermore, its habitat is threatened by widespread coastal development in the region. Anecdotal reports suggest that the Yantai stingray is significantly less common now in Chinese markets than it was in the past.

References

{{Taxonbar, from=Q140776 Hemitrygon Taxa named by Chu Yuan-Ting Fish described in 1960