Diamond stingray
Encyclopedia
The diamond stingray is a species
of stingray
in the family
Dasyatidae. It is found in the coastal waters of the eastern Pacific Ocean
from southern California
to northern Chile
, and around the Galápagos
and Hawaiian Islands
. This bottom-dweller generally inhabits sandy or muddy flats near rocky reef
s and kelp forest
s, to a depth of 30 m (98.4 ft), though off Hawaii it may range considerably deeper. As its common name
suggests, this species has an angular, diamond-shaped pectoral fin disc that is plain brown or gray above, with rows of tubercle
s along the midline and on the "shoulders". The long, whip-like tail has both dorsal and ventral fin folds, which distinguish this ray from the closely similar longtail stingray
(D. longa). It typically grows to 1 m (3.3 ft) across.
When searching for food, diamond stingrays may form groups of up to hundreds of individuals. It is most active at night and preys mainly on burrowing invertebrate
s and small bony fishes, which are extracted from the bottom via suction or digging. This species is aplacental viviparous: once the embryo
s exhaust their yolk supply, they are nourished by histotroph ("uterine milk") produced by the mother. Females bear 1–4 pups every summer in estuaries; mating
is followed by a ten-month period of either sperm
storage or arrested embryonic development
, after which the embryos rapidly mature over 2–3 months. The slowest-growing stingray known, this species is not resilient against fishing pressure. It is caught for food by artisanal fishers
in Latin America
, particularly in Mexico
where it is one of the most economically important rays. This has led it to be assessed as Near Threatened
in Mexico by the International Union for Conservation of Nature (IUCN), while the species as a whole is listed as Data Deficient
. Though innocuous towards humans, the diamond stingray's long, venom
ous tail spine is potentially dangerous.
and Charles Henry Gilbert
in Proceedings of the United States National Museum, and as Trygon brevis by Samuel Garman in Bulletin of the Museum of Comparative Zoology. Jordan and Gilbert's account was published in May while Garman's was published in October, making dipterurus (feminine
dipterura) the correct name as it was published first. However, when Garman synonymized
the two in 1913 he inappropriately gave precedence to brevis, leading to long-standing confusion. Both Dasybatus and Trygon were later synonymized with the genus Dasyatis, but many authors still listed D. brevis in place of or in addition to D. dipterura. Garman also synonymized the Hawaiian stingray (D. hawaiensis) with D. dipterura in 1913, which has since been followed by most authors but requires more study for confirmation.
The species syntype
s were collected from San Diego Bay
, California
. The specific epithet dipterura is derived from the Latin
di ("two"), ptero ("wing"), and ura ("tail"), referring to the fin folds on both sides of its tail. Rat-tailed stingray is a former common name
for this species. Lisa Rosenberger's 2001 phylogenetic analysis, based on morphology
, determined the diamond stingray and the bluntnose stingray
(D. say) of the western Atlantic Ocean
to be sister species, that likely diverged
before or with the formation of the Isthmus of Panama
(c. 3 Ma). In addition, the two were found to be the second-most basal taxa in their genus, after the common stingray
(D. pastinaca).
from southern California
to northern Chile
, as well as around the Galápagos
and Hawaiian Islands
; it is very abundant around Baja California
and in the Gulf of California
. At the northern and southern extremes of its range, it is generally only present during periods of suitably warm water brought about by El Niño. There is a record of this ray from off British Columbia
, which is unconfirmed and would be highly anomalous as it is known to be a tropical and warm-temperate
species.
A bottom-dwelling inhabitant of inshore waters, the diamond stingray favors sandy or muddy bottoms, often near rocky reef
s or kelp forest
s. Off southern California, it usually occurs from the intertidal zone
to a depth of 7 m (23 ft) during the summer, shifting to depths of 13–18 m (42.7–59.1 ft) during late fall and winter. For unknown reasons, it prefers to overwinter in kelp forests rather than sandy flats. Off Chile, the diamond stingray occurs at a similar depth of 3–30 m (9.8–98.4 ft). On the other hand, this species has been reported from as far down as 355 m (1,164.7 ft) off Hawaii, which if accurate would suggest that it utilizes a much greater range of depths than previously realized.
s (paired respiratory
openings). The mouth is strongly curved, containing 21–37 upper tooth rows and 23–44 lower tooth rows; the teeth are small and blunt, and arranged into flattened surfaces. Three or five papillae (nipple-like structures) are found in a row across the floor of the mouth.
The whip-like tail generally measures up to one and half times the length of the disc, and bears one (more if replacements have grown in) long, slender, serrated spine on the upper surface, closer to the base than the tip. Behind the spine, there are long dorsal and ventral fin folds that rise gradually, reaching a relatively high apex before sloping down abruptly. The presence of the upper fin fold separates this species from the similar longtail stingray
(D. longa), which shares most of its range. However, the tail is often damaged, in which case differentiating the two species in the field becomes all but impossible. Young rays have completely smooth skin, while adults develop a row of low tubercle
s along the midline of the back, flanked by two shorter rows on the "shoulders". The tail also becomes covered in prickles. This species is a uniform olive to brown to gray above, darkening to black on the tail, and off-white below.
The diamond stingray is most active at night, spending much of the day buried in sand with only its eyes protruding. When foraging for food, it may be solitary but more commonly forms groups numbering up to the hundreds. There is strong segregation by sex and age. This species feeds on crustacean
s, molluscs, and other invertebrate
s, as well as small bony fishes; its powerful jaws and molar-like teeth allow it to crush hard-shelled prey. It mainly targets burrowing organisms, but may also take prey exposed on the bottom. There is a record of a female 69 cm (27.2 in) across, that had gorged herself on at least 30 small crab
s. In the Bahía Magdalena lagoon
complex, Baja California Sur
, its most important source of food are pea crab
s, followed by the razor clam
Solyema valvulus, and then polychaete worms.
The typical hunting strategy of the diamond stingray is to cruise just above the sea floor, landing atop any prey encountered. It then quickly levers its body up-and-down with its disc, producing negative pressure
to extract the prey from its burrow. This ray has also been known to excavate large pits by undulating its disc and spitting jets of water, so as to uncover buried prey. Diamond stingrays are frequently trailed by smaller fishes, including Mexican hogfish (Bodianus diplotaenia), Galapagos porgies (Calamus taurinus), greybar grunts (Haemulon sexfasciatum), spinster wrasses (Halichoeres nichols), and long-spine porcupinefish (Diodon holocanthus), which take advantage of the invertebrates stirred up by the ray's activities. Known parasites of this species include the tapeworms Acanthobothrium bullardi, A. dasi, A. rajivi, and A. soberoni, Anthocephalum currani, Parachristianella tiygonis, and Pseudochristianello elegantissima, the flukes
Anaporrhutum euzeti and Probolitrema mexicana, and the monogenea
n Listrocephalos kearni.
Like other stingrays, the diamond stingray is aplacental viviparous: the embryo
s are initially nourished by yolk, and later by histotroph ("uterine milk", rich in protein
s and lipid
s) produced by the mother. Only the left ovary
and uterus
are functional in adult females. Several bays along the Pacific coast of Baja California are known to serve as nurseries. Most of the life history information available on this species has come from Bahía Magdalena, where females bear one litter of 1–4 pups per year. Courtship and mating
occurs in late summer from July to August, but due to a ten-month period of either sperm
storage or diapause
(wherein the embryo becomes dormant), embryonic development does not begin until the following year and is completed within 2–3 months. Birthing takes place in summer from July to September in shallow estuaries; the newborns measure 18–23 cm (7.1–9.1 in) across. During El Niño years, the higher temperatures appear to shift the timing of birth forward. The diamond stingray has the lowest growth rate of any stingray species yet studied. Males reach sexual maturity
at around 43–47 cm (16.9–18.5 in) across and 7 years of age, while females grow slower still, reaching maturity at around 57–66 cm (22.4–26 in) across and 10 years of age. The maximum lifespan has been estimated at least 19 years for males and 28 years for females.
ous tail spine of the diamond stingray. However, it is not aggressive and will usually flee given the opportunity. This ray is not found off the United States
in sufficient numbers to be economically important. Elsewhere in its range, it is caught in substantial numbers for human consumption, both intentionally and as bycatch
; the pectoral fins or "wings" are sold fresh or fillet
ed and salted
. The International Union for Conservation of Nature (IUCN) notes that the diamond stingray's low reproductive productivity renders it susceptible to population depletion, but currently lacks enough biological and fishery data to assess it beyond Data Deficient
overall, or in the U.S., Central
, and South America
n parts of its range.
In Mexico
, the diamond stingray is one of the most important components of Pacific artisanal
shark and ray fisheries, comprising around a tenth of the total annual catch. Its significance is likely underestimated, as Mexican fishery reports frequently suffer from misidentifications and a lack of species-specific data. It is mainly caught during summer and fall, being the most common ray landed in Bahía Magdalena, and second most common ray landed off Sonora
state. Demersal gillnet
s are the main fishing gear employed; both adult and juvenile rays easily become entangled in the mesh by their tail spines, with juveniles known to have comprised most of the Bahía Magdalena catch in 1998–2000. This species is also often caught incidentally in bottom trawls, on longlines, and in fish trap
s. In the future, habitat degradation from increasing numbers of shrimp farm
s may pose an additional threat to this species in the region. As a result of these pressures, the IUCN has assessed the diamond stingray as Near Threatened
in Mexican waters. No management schemes have yet been enacted for this species.
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. It is found in the coastal waters of the eastern 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...
from southern California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
to northern Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
, and around the Galápagos
Galápagos Islands
The Galápagos Islands are an archipelago of volcanic islands distributed around the equator in the Pacific Ocean, west of continental Ecuador, of which they are a part.The Galápagos Islands and its surrounding waters form an Ecuadorian province, a national park, and a...
and Hawaiian Islands
Hawaiian Islands
The Hawaiian Islands are an archipelago of eight major islands, several atolls, numerous smaller islets, and undersea seamounts in the North Pacific Ocean, extending some 1,500 miles from the island of Hawaii in the south to northernmost Kure Atoll...
. This bottom-dweller generally inhabits sandy or muddy flats near rocky reef
Reef
In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....
s and kelp forest
Kelp forest
Kelp forests are underwater areas with a high density of kelp. They are recognized as one of the most productive and dynamic ecosystems on Earth. Smaller areas of anchored kelp are called kelp beds....
s, to a depth of 30 m (98.4 ft), though off Hawaii it may range considerably deeper. As its common name
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
suggests, this species has an angular, diamond-shaped pectoral fin disc that is plain brown or gray above, with rows of tubercle
Tubercle
A tubercle is generally a wart-like projection, but it has slightly different meaning depending on which family of plants or animals it is used to refer to....
s along the midline and on the "shoulders". The long, whip-like tail has both dorsal and ventral fin folds, which distinguish this ray from the closely similar longtail stingray
Longtail stingray
The longtail stingray , is a species of stingray in the family Dasyatidae, found in the eastern Pacific Ocean from Baja California to Colombia. It inhabits sandy habitats down to a depth of...
(D. longa). It typically grows to 1 m (3.3 ft) across.
When searching for food, diamond stingrays may form groups of up to hundreds of individuals. It is most active at night and preys mainly on burrowing invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s and small bony fishes, which are extracted from the bottom via suction or digging. This species is aplacental viviparous: once the embryo
Embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
s exhaust their yolk supply, they are nourished by histotroph ("uterine milk") produced by the mother. Females bear 1–4 pups every summer in estuaries; mating
Mating
In biology, mating is the pairing of opposite-sex or hermaphroditic organisms for copulation. In social animals, it also includes the raising of their offspring. Copulation is the union of the sex organs of two sexually reproducing animals for insemination and subsequent internal fertilization...
is followed by a ten-month period of either sperm
Sperm
The term sperm is derived from the Greek word sperma and refers to the male reproductive cells. In the types of sexual reproduction known as anisogamy and oogamy, there is a marked difference in the size of the gametes with the smaller one being termed the "male" or sperm cell...
storage or arrested embryonic development
Embryonic diapause
Delayed Implantation or Embryonic Diapause is a reproductive strategy used by approximately 100 different mammals in seven or eight different orders. In embryonic diapause, the embryo does not immediately implant in the uterus, but is maintained in a state of dormancy. Little to no development...
, after which the embryos rapidly mature over 2–3 months. The slowest-growing stingray known, this species is not resilient against fishing pressure. It is caught for food by artisanal fishers
Artisan fishing
Artisan fishing is a term used to describe small scale low-technology commercial or subsistence fishing practices. The term particularly applies to coastal or island ethnic groups using traditional techniques such as rod and tackle, arrows and harpoons, throw nets and drag nets, and traditional...
in Latin America
Latin America
Latin America is a region of the Americas where Romance languages – particularly Spanish and Portuguese, and variably French – are primarily spoken. Latin America has an area of approximately 21,069,500 km² , almost 3.9% of the Earth's surface or 14.1% of its land surface area...
, particularly in Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
where it is one of the most economically important rays. This has led it to be 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...
in Mexico by the International Union for Conservation of Nature (IUCN), while the species as a whole is listed 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...
. Though innocuous towards humans, the diamond stingray's long, venom
Venom
Venom is the general term referring to any variety of toxins used by certain types of animals that inject it into their victims by the means of a bite or a sting...
ous tail spine is potentially dangerous.
Taxonomy and phylogeny
In 1880, the diamond stingray was described twice by three American ichthyologists: as Dasybatus dipterurus by David Starr JordanDavid Starr Jordan
David Starr Jordan, Ph.D., LL.D. was a leading eugenicist, ichthyologist, educator and peace activist. He was president of Indiana University and Stanford University.-Early life and education:...
and Charles Henry Gilbert
Charles Henry Gilbert
Charles Henry Gilbert was a pioneer ichthyologist and fishery biologist of particular significance to natural history of the western United States. He collected and studied fishes from Central America north to Alaska and described many new species...
in Proceedings of the United States National Museum, and as Trygon brevis by Samuel Garman in Bulletin of the Museum of Comparative Zoology. Jordan and Gilbert's account was published in May while Garman's was published in October, making dipterurus (feminine
Grammatical gender
Grammatical gender is defined linguistically as a system of classes of nouns which trigger specific types of inflections in associated words, such as adjectives, verbs and others. For a system of noun classes to be a gender system, every noun must belong to one of the classes and there should be...
dipterura) the correct name as it was published first. However, when Garman 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...
the two in 1913 he inappropriately gave precedence to brevis, leading to long-standing confusion. Both Dasybatus and Trygon were later synonymized with the genus Dasyatis, but many authors still listed D. brevis in place of or in addition to D. dipterura. Garman also synonymized the Hawaiian stingray (D. hawaiensis) with D. dipterura in 1913, which has since been followed by most authors but requires more study for confirmation.
The species 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 were collected from San Diego Bay
San Diego Bay
San Diego Bay is a natural harbor and deepwater port adjacent to San Diego, California. It is 12 mi/19 km long, 1 mi/1.6 km–3 mi/4.8 km wide...
, California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
. The specific epithet dipterura is derived from the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
di ("two"), ptero ("wing"), and ura ("tail"), referring to the fin folds on both sides of its tail. Rat-tailed stingray is a former common name
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
for this species. Lisa Rosenberger's 2001 phylogenetic analysis, based on morphology
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....
, determined the diamond stingray and the bluntnose stingray
Bluntnose stingray
The bluntnose stingray or Say's stingray is a species of stingray in the family Dasyatidae, native to the coastal waters of the western Atlantic Ocean from the U.S. state of Massachusetts to Venezuela. It is a bottom-dwelling species that prefers sandy or muddy habitats deep, and is migratory in...
(D. say) of the western Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
to be sister species, that likely diverged
Speciation
Speciation is the evolutionary process by which new biological species arise. The biologist Orator F. Cook seems to have been the first to coin the term 'speciation' for the splitting of lineages or 'cladogenesis,' as opposed to 'anagenesis' or 'phyletic evolution' occurring within lineages...
before or with the formation of the Isthmus of Panama
Isthmus of Panama
The Isthmus of Panama, also historically known as the Isthmus of Darien, is the narrow strip of land that lies between the Caribbean Sea and the Pacific Ocean, linking North and South America. It contains the country of Panama and the Panama Canal...
(c. 3 Ma). In addition, the two were found to be the second-most basal taxa in their genus, after the common stingray
Common stingray
The common stingray is a species of stingray in the family Dasyatidae, found in the northeastern Atlantic Ocean and the Mediterranean and Black Seas. It typically inhabits sandy or muddy habitats in coastal waters shallower than , often burying itself in sediment...
(D. pastinaca).
Distribution and habitat
The diamond stingray is found in the eastern Pacific OceanPacific 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...
from southern California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
to northern Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
, as well as around the Galápagos
Galápagos Islands
The Galápagos Islands are an archipelago of volcanic islands distributed around the equator in the Pacific Ocean, west of continental Ecuador, of which they are a part.The Galápagos Islands and its surrounding waters form an Ecuadorian province, a national park, and a...
and Hawaiian Islands
Hawaiian Islands
The Hawaiian Islands are an archipelago of eight major islands, several atolls, numerous smaller islets, and undersea seamounts in the North Pacific Ocean, extending some 1,500 miles from the island of Hawaii in the south to northernmost Kure Atoll...
; it is very abundant around Baja California
Baja California
Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...
and in the Gulf of California
Gulf of California
The Gulf of California is a body of water that separates the Baja California Peninsula from the Mexican mainland...
. At the northern and southern extremes of its range, it is generally only present during periods of suitably warm water brought about by El Niño. There is a record of this ray from off British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
, which is unconfirmed and would be highly anomalous as it is known to be a tropical and warm-temperate
Temperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...
species.
A bottom-dwelling inhabitant of inshore waters, the diamond stingray favors sandy or muddy bottoms, often near rocky reef
Reef
In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....
s or kelp forest
Kelp forest
Kelp forests are underwater areas with a high density of kelp. They are recognized as one of the most productive and dynamic ecosystems on Earth. Smaller areas of anchored kelp are called kelp beds....
s. Off southern California, it usually occurs from the intertidal zone
Intertidal zone
The intertidal zone is the area that is above water at low tide and under water at high tide . This area can include many different types of habitats, with many types of animals like starfish, sea urchins, and some species of coral...
to a depth of 7 m (23 ft) during the summer, shifting to depths of 13–18 m (42.7–59.1 ft) during late fall and winter. For unknown reasons, it prefers to overwinter in kelp forests rather than sandy flats. Off Chile, the diamond stingray occurs at a similar depth of 3–30 m (9.8–98.4 ft). On the other hand, this species has been reported from as far down as 355 m (1,164.7 ft) off Hawaii, which if accurate would suggest that it utilizes a much greater range of depths than previously realized.
Description
The diamond stingray attains a disc width of 1 m (3.3 ft) or possibly 1.2 m (3.9 ft); females grow larger than males. Its pectoral fin disc is rhomboid in shape, slightly wider than long, with angular outer corners and subtly convex margins. The snout is blunt-angled and non-projecting. The eyes are fairly large and immediately followed by the 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 (paired respiratory
Respiration (physiology)
'In physiology, respiration is defined as the transport of oxygen from the outside air to the cells within tissues, and the transport of carbon dioxide in the opposite direction...
openings). The mouth is strongly curved, containing 21–37 upper tooth rows and 23–44 lower tooth rows; the teeth are small and blunt, and arranged into flattened surfaces. Three or five papillae (nipple-like structures) are found in a row across the floor of the mouth.
The whip-like tail generally measures up to one and half times the length of the disc, and bears one (more if replacements have grown in) long, slender, serrated spine on the upper surface, closer to the base than the tip. Behind the spine, there are long dorsal and ventral fin folds that rise gradually, reaching a relatively high apex before sloping down abruptly. The presence of the upper fin fold separates this species from the similar longtail stingray
Longtail stingray
The longtail stingray , is a species of stingray in the family Dasyatidae, found in the eastern Pacific Ocean from Baja California to Colombia. It inhabits sandy habitats down to a depth of...
(D. longa), which shares most of its range. However, the tail is often damaged, in which case differentiating the two species in the field becomes all but impossible. Young rays have completely smooth skin, while adults develop a row of low tubercle
Tubercle
A tubercle is generally a wart-like projection, but it has slightly different meaning depending on which family of plants or animals it is used to refer to....
s along the midline of the back, flanked by two shorter rows on the "shoulders". The tail also becomes covered in prickles. This species is a uniform olive to brown to gray above, darkening to black on the tail, and off-white below.
Biology and ecology
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, molluscs, and other invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s, as well as small bony fishes; its powerful jaws and molar-like teeth allow it to crush hard-shelled prey. It mainly targets burrowing organisms, but may also take prey exposed on the bottom. There is a record of a female 69 cm (27.2 in) across, that had gorged herself on at least 30 small crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
s. In the Bahía Magdalena lagoon
Lagoon
A lagoon is a body of shallow sea water or brackish water separated from the sea by some form of barrier. The EU's habitat directive defines lagoons as "expanses of shallow coastal salt water, of varying salinity or water volume, wholly or partially separated from the sea by sand banks or shingle,...
complex, Baja California Sur
Baja California Sur
Baja California Sur , is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. Before becoming a state on October 8, 1974, the area was known as the South Territory of Baja California. It has an area of , or 3.57% of the land mass of Mexico and comprises...
, its most important source of food are pea crab
Pea crab
The New Zealand pea crab, Pinnotheres novaezelandiae, is a small, parasitic crab that lives most commonly inside New Zealand green-lipped mussels. Adult females are about the size and shape of a pea, while adult males are smaller and flatter. Adult New Zealand pea crabs are completely reliant on...
s, followed by the razor clam
Razor clam
Razor clam may refer to clams in the genus Ensis or Siliqua, including:*Ensis directus, Atlantic jackknife clam*Ensis arcuatus, razor shell*Siliqua patula, Pacific razor clam...
Solyema valvulus, and then polychaete worms.
The typical hunting strategy of the diamond stingray is to cruise just above the sea floor, landing atop any prey encountered. It then quickly levers its body up-and-down with its disc, producing negative pressure
Suction
Suction is the flow of a fluid into a partial vacuum, or region of low pressure. The pressure gradient between this region and the ambient pressure will propel matter toward the low pressure area. Suction is popularly thought of as an attractive effect, which is incorrect since vacuums do not...
to extract the prey from its burrow. This ray has also been known to excavate large pits by undulating its disc and spitting jets of water, so as to uncover buried prey. Diamond stingrays are frequently trailed by smaller fishes, including Mexican hogfish (Bodianus diplotaenia), Galapagos porgies (Calamus taurinus), greybar grunts (Haemulon sexfasciatum), spinster wrasses (Halichoeres nichols), and long-spine porcupinefish (Diodon holocanthus), which take advantage of the invertebrates stirred up by the ray's activities. Known parasites of this species include the tapeworms Acanthobothrium bullardi, A. dasi, A. rajivi, and A. soberoni, Anthocephalum currani, Parachristianella tiygonis, and Pseudochristianello elegantissima, the flukes
Trematoda
Trematoda is a class within the phylum Platyhelminthes that contains two groups of parasitic flatworms, commonly referred to as "flukes".-Taxonomy and biodiversity:...
Anaporrhutum euzeti and Probolitrema mexicana, 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 Listrocephalos kearni.
Like other stingrays, the diamond stingray is aplacental viviparous: the embryo
Embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
s are initially nourished by yolk, and later by histotroph ("uterine milk", rich in protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
s and lipid
Lipid
Lipids constitute a broad group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins , monoglycerides, diglycerides, triglycerides, phospholipids, and others...
s) produced by the mother. Only the left ovary
Ovary
The ovary is an ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system. Ovaries in anatomically female individuals are analogous to testes in anatomically male individuals, in that they are both gonads and endocrine glands.-Human anatomy:Ovaries...
and uterus
Uterus
The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...
are functional in adult females. Several bays along the Pacific coast of Baja California are known to serve as nurseries. Most of the life history information available on this species has come from Bahía Magdalena, where females bear one litter of 1–4 pups per year. Courtship and mating
Mating
In biology, mating is the pairing of opposite-sex or hermaphroditic organisms for copulation. In social animals, it also includes the raising of their offspring. Copulation is the union of the sex organs of two sexually reproducing animals for insemination and subsequent internal fertilization...
occurs in late summer from July to August, but due to a ten-month period of either sperm
Sperm
The term sperm is derived from the Greek word sperma and refers to the male reproductive cells. In the types of sexual reproduction known as anisogamy and oogamy, there is a marked difference in the size of the gametes with the smaller one being termed the "male" or sperm cell...
storage or diapause
Embryonic diapause
Delayed Implantation or Embryonic Diapause is a reproductive strategy used by approximately 100 different mammals in seven or eight different orders. In embryonic diapause, the embryo does not immediately implant in the uterus, but is maintained in a state of dormancy. Little to no development...
(wherein the embryo becomes dormant), embryonic development does not begin until the following year and is completed within 2–3 months. Birthing takes place in summer from July to September in shallow estuaries; the newborns measure 18–23 cm (7.1–9.1 in) across. During El Niño years, the higher temperatures appear to shift the timing of birth forward. The diamond stingray has the lowest growth rate of any stingray species yet studied. Males reach sexual maturity
Sexual maturity
Sexual maturity is the age or stage when an organism can reproduce. It is sometimes considered synonymous with adulthood, though the two are distinct...
at around 43–47 cm (16.9–18.5 in) across and 7 years of age, while females grow slower still, reaching maturity at around 57–66 cm (22.4–26 in) across and 10 years of age. The maximum lifespan has been estimated at least 19 years for males and 28 years for females.
Human interactions
At least one fatality off southern California has resulted from the long, venomVenom
Venom is the general term referring to any variety of toxins used by certain types of animals that inject it into their victims by the means of a bite or a sting...
ous tail spine of the diamond stingray. However, it is not aggressive and will usually flee given the opportunity. This ray is not found off the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
in sufficient numbers to be economically important. Elsewhere in its range, it is caught in substantial numbers for human consumption, both intentionally and 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...
; the pectoral fins or "wings" are sold fresh or fillet
Fillet (cut)
A fillet is a cut or slice of boneless meat or fish.- Meat :In the case of beef, in the USA, the term most often refers to beef tenderloin, especially filet mignon.- Chicken :...
ed and salted
Salting (food)
Salting is the preservation of food with dry edible salt. It is related to pickling . It is one of the oldest methods of preserving food, and two historically significant salt-cured foods are dried and salted cod and salt-cured meat.Salting is used because most bacteria, fungi and other potentially...
. The International Union for Conservation of Nature (IUCN) notes that the diamond stingray's low reproductive productivity renders it susceptible to population depletion, but currently lacks enough biological and fishery data to assess it 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...
overall, or in the U.S., Central
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...
, and South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
n parts of its range.
In Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
, the diamond stingray is one of the most important components of Pacific artisanal
Artisan fishing
Artisan fishing is a term used to describe small scale low-technology commercial or subsistence fishing practices. The term particularly applies to coastal or island ethnic groups using traditional techniques such as rod and tackle, arrows and harpoons, throw nets and drag nets, and traditional...
shark and ray fisheries, comprising around a tenth of the total annual catch. Its significance is likely underestimated, as Mexican fishery reports frequently suffer from misidentifications and a lack of species-specific data. It is mainly caught during summer and fall, being the most common ray landed in Bahía Magdalena, and second most common ray landed off Sonora
Sonora
Sonora officially Estado Libre y Soberano de Sonora is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided into 72 municipalities; the capital city is Hermosillo....
state. Demersal 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 are the main fishing gear employed; both adult and juvenile rays easily become entangled in the mesh by their tail spines, with juveniles known to have comprised most of the Bahía Magdalena catch in 1998–2000. This species is also often caught incidentally in bottom trawls, on longlines, and in fish trap
Fish trap
A fish trap is a trap used for fishing. Fish traps may have the form of a fishing weir or a lobster trap. A typical trap might consist of a frame of thick steel wire in the shape of a heart, with chicken wire stretched around it. The mesh wraps around the frame and then tapers into the inside of...
s. In the future, habitat degradation from increasing numbers of shrimp farm
Shrimp farm
A shrimp farm is an aquaculture business for the cultivation of marine shrimp or prawns for human consumption. Commercial shrimp farming began in the 1970s, and production grew steeply, particularly to match the market demands of the United States, Japan and Western Europe...
s may pose an additional threat to this species in the region. As a result of these pressures, the IUCN has assessed the diamond 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...
in Mexican waters. No management schemes have yet been enacted for this species.