Pale-edged stingray
Encyclopedia
The pale-edged stingray or sharpnose stingray (Dasyatis zugei) is a species
of stingray
in the family
Dasyatidae, found in the Indian
and Pacific Ocean
s from India
to the western Malay Archipelago
and southern Japan
. This bottom-dwelling ray is most commonly found over sandy areas shallower than 100 m (328.1 ft), as well as in estuaries. Measuring up to 29 cm (11.4 in) across, the pale-edged stingray has a diamond-shaped pectoral fin disc, a long projecting snout, small eyes, and a whip-like tail with both dorsal and ventral fin folds. It is chocolate brown above and white below.
The diet of the pale-edged stingray consists mainly of small crustacean
s and fish
es. Reproduction is aplacental viviparous, with females bearing litters of 1–3 young. Caught as bycatch
and utilized for its meat, this species is threatened by heavy fishing pressure throughout its range and has been assessed as Near Threatened
by the International Union for Conservation of Nature (IUCN).
and Friedrich Henle
originally described the pale-edged stingray from seven syntype
s, in their 1841 Systematische Beschreibung der Plagiostomen. They named it Trygon zugei after zugu-ei, the Japanese name for this species. The genus Trygon was synonymized
with Dasyatis by subsequent authors. Several early accounts of D. zugei were confounded by specimens of D. acutirostra
; in 1988 Nishida and Nakaya published a study that resolved the differences between these two species and designated a new lectotype
for D. zugei.
Lisa Rosenberger's 2001 phylogenetic analysis, based on morphological
characters, found that the pale-edged stingray is sister to a clade
containing the whitespotted whipray (Himantura gerrardi), the pearl stingray
(D. margaritella), and the smooth butterfly ray
(Gymnura micrura). These results support the growing consensus that neither Dasyatis nor Himantura are monophyletic.
eastward to Java
and Borneo
, and northward to the Philippines
and southern Japan
. This species inhabits the inner continental shelf
, favoring sandy flats in water under 100 m (328.1 ft) deep, and also frequently enters estuaries.
s immediately behind. There is a nearly rectangular curtain of skin between the nares, with a fringed rear margin. The mouth is gently curved, without papilla
e on the floor. There are 40–55 tooth rows in either jaw, arranged with a quincunx
pattern into pavement-like surfaces. The teeth of adult males have pointed cusps while those of juveniles and females are blunt.
The pelvic fins are triangular. The tail is whip-like, much longer than the disc, and bears a stinging spine. A low dorsal fin fold originates just posterior of the spine tip while a deeper ventral fin fold originates below the spine base. Young individuals have smooth skin, while adults have a row of 5–9 small tubercles in front of the spine. The dorsal surface is a uniform chocolate brown, darkening on the tail fin folds, while the underside is white with a brown band around the margin of the disc. This species reaches a length of 75 cm (29.5 in) and width of 29 cm (11.4 in), though most do not exceed 18–24 cm (7.1–9.4 in) in width. The pale-edged stingray differs from the similar but larger D. acutirostra in having smaller eyes and an upper tail fin fold, as well as in several meristic counts such as the number of intestinal valves.
s, in particular prawn
s, but also takes small fish
es. Parasites
that have been identified from this species include the tapeworms Acanthobothrium zugeinensis, Balanobothrium yamagutii, Pithophorus zugeii, Polypocephalus ratnagiriensis and P. visakhapatnamensis, Rhinebothrium xiamenensis, Shindeiobothrium karbharae, Tetragonocephalum raoi, Tylocephalum singhii, and Uncibilocularis indiana and U. veravalensis, and the monogenea
n Trimusculotrema schwartzi. Like other stingrays, the pale-edged stingray is aplacental viviparous, with the young sustained initially by yolk and later histotroph ("uterine milk") secreted by the mother. Females give birth to 1–3 young at a time; there is no defined reproductive seasonality, at least in Indonesia
n waters. Newborns measure 8–10 cm (3.1–3.9 in) across. Males mature sexually at a disc width of 18 cm (7.1 in) and females at a disc width of 19 cm (7.5 in).
in bottom trawls and trammel nets, particularly in the Gulf of Thailand
, the Java Sea
, and off the Indian coast. Most individuals landed are retained for human consumption, although the small size of this species limits its economic significance. The International Union for Conservation of Nature (IUCN) has assessed the pale-edged stingray as Near Threatened
and notes that it is approaching the criteria for Vulnerable
. Across most of its range, this species experiences heavy and increasing fishing pressure, with all size classes susceptible to capture.
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, found in the Indian
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
and Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
s from India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
to the western Malay Archipelago
Malay Archipelago
The Malay Archipelago refers to the archipelago between mainland Southeastern Asia and Australia. The name was derived from the anachronistic concept of a Malay race....
and southern 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...
. This bottom-dwelling ray is most commonly found over sandy areas shallower than 100 m (328.1 ft), as well as in estuaries. Measuring up to 29 cm (11.4 in) across, the pale-edged stingray has a diamond-shaped pectoral fin disc, a long projecting snout, small eyes, and a whip-like tail with both dorsal and ventral fin folds. It is chocolate brown above and white below.
The diet of the pale-edged stingray consists mainly of small crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s and fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
es. Reproduction is aplacental viviparous, with females bearing litters of 1–3 young. 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...
and utilized for its meat, this species is threatened by heavy fishing pressure throughout its range and has been assessed as Near Threatened
Near Threatened
Near Threatened is a conservation status assigned to species or lower taxa that may be considered threatened with extinction in the near future, although it does not currently qualify for the threatened status...
by the International Union for Conservation of Nature (IUCN).
Taxonomy and phylogeny
German biologists Johannes MüllerJohannes Peter Müller
Johannes Peter Müller , was a German physiologist, comparative anatomist, and ichthyologist not only known for his discoveries but also for his ability to synthesize knowledge.-Early years and education:...
and Friedrich Henle
Friedrich Gustav Jakob Henle
Friedrich Gustav Jakob Henle was a German physician, pathologist and anatomist. He is credited with the discovery of the loop of Henle in the kidney. His essay "On Miasma and Contagia" was an early argument for the germ theory of disease...
originally described the pale-edged stingray from seven syntype
Syntype
In biological nomenclature, a syntype is a term used to indicate a specimen with a special status.In zoological nomenclature, a syntype is defined as "Each specimen of a type series from which neither a holotype nor a lectotype has been designated [Arts. 72.1.2, 73.2, 74]. The syntypes...
s, in their 1841 Systematische Beschreibung der Plagiostomen. They named it Trygon zugei after zugu-ei, the Japanese name for this species. The genus Trygon was synonymized
Synonym (taxonomy)
In scientific nomenclature, a synonym is a scientific name that is or was used for a taxon of organisms that also goes by a different scientific name. For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies...
with Dasyatis by subsequent authors. Several early accounts of D. zugei were confounded by specimens of D. acutirostra
Dasyatis acutirostra
The sharpnose stingray is a little-known species of stingray in the family Dasyatidae, found off southern Japan and in the East China Sea. With a rounded pectoral fin disc and a long, projecting snout, D. acutirostra resembles the smaller pale-edged stingray...
; in 1988 Nishida and Nakaya published a study that resolved the differences between these two species and designated a new lectotype
Lectotype
In botanical nomenclature and zoological nomenclature, a lectotype is a kind of name-bearing type. When a species was originally described on the basis of a name-bearing type consisting of multiple specimens, one of those may be designated as the lectotype...
for D. zugei.
Lisa Rosenberger's 2001 phylogenetic analysis, based on morphological
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
characters, found that the pale-edged stingray is sister to a clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
containing the whitespotted whipray (Himantura gerrardi), the pearl stingray
Pearl stingray
The pearl stingray is a little-known species of stingray in the family Dasyatidae, found in shallow coastal waters from Mauritania to Angola. Growing to across, this species has a rounded pectoral fin disc with a pointed snout, and a wide band of dermal denticles over the back in adults...
(D. margaritella), and the smooth butterfly ray
Smooth butterfly ray
The smooth butterfly ray is a species of fish in the Gymnuridae family. It is found in Belize, Brazil, Cameroon, Colombia, the Democratic Republic of the Congo, Costa Rica, French Guiana, Gambia, Guatemala, Guyana, Honduras, Mexico, Nicaragua, Panama, Senegal, Sierra Leone, Suriname, Trinidad and...
(Gymnura micrura). These results support the growing consensus that neither Dasyatis nor Himantura are monophyletic.
Distribution and habitat
The range of the pale-edged stingray extends from the Indian subcontinentIndian subcontinent
The Indian subcontinent, also Indian Subcontinent, Indo-Pak Subcontinent or South Asian Subcontinent is a region of the Asian continent on the Indian tectonic plate from the Hindu Kush or Hindu Koh, Himalayas and including the Kuen Lun and Karakoram ranges, forming a land mass which extends...
eastward to Java
Java
Java is an island of Indonesia. With a population of 135 million , it is the world's most populous island, and one of the most densely populated regions in the world. It is home to 60% of Indonesia's population. The Indonesian capital city, Jakarta, is in west Java...
and Borneo
Borneo
Borneo is the third largest island in the world and is located north of Java Island, Indonesia, at the geographic centre of Maritime Southeast Asia....
, and northward to the Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
and southern 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...
. This species inhabits the inner continental shelf
Continental 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,...
, favoring sandy flats in water under 100 m (328.1 ft) deep, and also frequently enters estuaries.
Description
The pale-edged stingray has a diamond-shaped pectoral fin disc slightly longer than wide, with concave anterior margins merging into an elongated, triangular snout; the head comprises more than half of the disc length. The eyes are small, with a pair of much larger spiracleSpiracle
Spiracles are openings on the surface of some animals that usually lead to respiratory systems.-Vertebrates:The spiracle is a small hole behind each eye that opens to the mouth in some fishes. In the primitive jawless fish the first gill opening immediately behind the mouth is essentially similar...
s immediately behind. There is a nearly rectangular curtain of skin between the nares, with a fringed rear margin. The mouth is gently curved, without papilla
Papilla (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 on the floor. There are 40–55 tooth rows in either jaw, arranged with a quincunx
Quincunx
A quincunx is a geometric pattern consisting of five points arranged in a cross, that is five coplanar points, four of them forming a square or rectangle and a fifth at its center...
pattern into pavement-like surfaces. The teeth of adult males have pointed cusps while those of juveniles and females are blunt.
The pelvic fins are triangular. The tail is whip-like, much longer than the disc, and bears a stinging spine. A low dorsal fin fold originates just posterior of the spine tip while a deeper ventral fin fold originates below the spine base. Young individuals have smooth skin, while adults have a row of 5–9 small tubercles in front of the spine. The dorsal surface is a uniform chocolate brown, darkening on the tail fin folds, while the underside is white with a brown band around the margin of the disc. This species reaches a length of 75 cm (29.5 in) and width of 29 cm (11.4 in), though most do not exceed 18–24 cm (7.1–9.4 in) in width. The pale-edged stingray differs from the similar but larger D. acutirostra in having smaller eyes and an upper tail fin fold, as well as in several meristic counts such as the number of intestinal valves.
Biology and ecology
The pale-edged stingray feeds mainly on bottom-dwelling crustaceanCrustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s, in particular prawn
Prawn
Prawns are decapod crustaceans of the sub-order Dendrobranchiata. There are 540 extant species, in seven families, and a fossil record extending back to the Devonian...
s, but also takes small fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
es. Parasites
Parasitism
Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred to organisms with lifestages that needed more than one host . These are now called macroparasites...
that have been identified from this species include the tapeworms Acanthobothrium zugeinensis, Balanobothrium yamagutii, Pithophorus zugeii, Polypocephalus ratnagiriensis and P. visakhapatnamensis, Rhinebothrium xiamenensis, Shindeiobothrium karbharae, Tetragonocephalum raoi, Tylocephalum singhii, and Uncibilocularis indiana and U. veravalensis, and the monogenea
Monogenea
Monogenea are a group of largely ectoparasitic members of the flatworm phylum Platyhelminthes, class Monogenea.-Characteristics:Monogenea are very small parasitic flatworms mainly found on skin or gills of fish....
n Trimusculotrema schwartzi. Like other stingrays, the pale-edged stingray is aplacental viviparous, with the young sustained initially by yolk and later histotroph ("uterine milk") secreted by the mother. Females give birth to 1–3 young at a time; there is no defined reproductive seasonality, at least in Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
n waters. Newborns measure 8–10 cm (3.1–3.9 in) across. Males mature sexually at a disc width of 18 cm (7.1 in) and females at a disc width of 19 cm (7.5 in).
Human interactions
Large numbers of pale-edged stingrays are 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...
in bottom trawls and trammel nets, particularly in the Gulf of Thailand
Gulf of Thailand
The Gulf of Thailand , also known in to Malays as Teluk Siam literally meant Gulf of Siam, is a shallow arm of the South China Sea.-Geography:...
, the Java Sea
Java Sea
The Java Sea is a large shallow sea on the Sunda Shelf. It was formed as sea levels rose at the end of the last ice age. The Java Sea lies between the Indonesian islands of Borneo to the north, Java to the south; Sumatra to the west, and Sulawesi to the east...
, and off the Indian coast. Most individuals landed are retained for human consumption, although the small size of this species limits its economic significance. The International Union for Conservation of Nature (IUCN) has assessed the pale-edged stingray as Near Threatened
Near Threatened
Near Threatened is a conservation status assigned to species or lower taxa that may be considered threatened with extinction in the near future, although it does not currently qualify for the threatened status...
and notes that it is approaching the criteria for Vulnerable
Vulnerable species
On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...
. Across most of its range, this species experiences heavy and increasing fishing pressure, with all size classes susceptible to capture.