Daisy stingray
Encyclopedia
The daisy stingray, Dasyatis margarita, is a little-known species
of stingray
in the family
Dasyatidae, found in shallow coastal waters along the coast of West Africa
. This species typically grows to 60 cm (23.6 in) across and has a rounded pectoral fin disc and (in adults) a wide band of dermal denticles over its back. It is characterized by a greatly enlarged, nacre
ous denticle in the middle of its back called a "pearl spine"; this feature is shared with the similar but much smaller pearl stingray
(D. margaritella), which has often been confused with this species. The daisy stingray feeds mainly on crustacean
s and exhibits aplacental viviparity, with litters of 1–4 young. Heavily pressured by fisheries and possibly habitat degradation, this once-common species is declining and has been assessed as Endangered by the International Union for Conservation of Nature (IUCN).
(D. garouaensis), both also native to West Africa. Numerous scientific accounts of the daisy stingray have been confounded by confusion with the pearl stingray; this confusion dates back to the two West African specimens referenced in Günther's original description. In 1984, Leonard Compagno
and Tyson Roberts identified one of them as a pearl stingray and designated the other as the lectotype
for this species. The specific epithet margarita is derived from the Latin
for "pearl
", referring to the large tubercle on its back.
to the Democratic Republic of the Congo
; records of it occurring as far as Mauritania
and Angola
may have been mistakenly based on the pearl stingray. This bottom-dwelling species is found in marine
and brackish water
s with a salinity
of 20–40 ppt. It favors sandy habitat
s in shallow coastal waters to a depth of 60 m (196.9 ft), though most are found between 11 and 20 m (36.1 and 65.6 ft). This ray also reportedly frequents lagoon
s and estuaries; however, this also requires confirmation due to confusion with the pearl stingray.
s. There is a curtain of skin between the nares, with a fringed, subtly tri-lobed posterior margin; a pair of shallow grooves run from the skin flap to the corners of the bow-shaped mouth. There are 5 papilla
e in a transverse row across the floor of the mouth, with the outermost pair set apart from the others. The tooth rows number 24–32 in the upper jaw and 28–36 rows in the lower jaw, and are arranged with a quincunx
pattern into pavement-like surfaces. The pelvic fins are short, with the tips projecting just past the disc margin.
The tail is longer than the disc and usually bears a single long, thin stinging spine on the upper surface. The tail is broad and flattened at the base, becoming slender and whip-like past the spine with a low dorsal keel and a well-developed ventral fin fold. There is a massive, circular pearl spine at the center of the disc. Young rays are otherwise smooth-skinned, while older rays over 20 cm (7.9 in) across gain a wide band of small, flattened, circular dermal denticles covering the median third of the back from between the eyes to the base of the tail, as well as small prickles covering the tail behind the sting. This ray is a plain grayish brown above, and whitish below. It reaches a maximum known disc width of 1 m (3.3 ft) and weight of 17 kg (37.5 lb), though most do not exceed a width of 60 cm (23.6 in). Females grow larger than males. Apart from being much larger, the daisy stingray can also be distinguished from the pearl stingray in having a relatively larger, round pearl spine, fewer tooth rows, and more pectoral fin radials (129–136 versus 113–127).
, crab
s, bivalves, and annelid worms. Off Nigeria
, some three-quarters of its diet consists of the shrimp
Farfantepenaeus duorarum. Like other stingrays, this species is aplacental viviparous. Females bear litters of 1–4 pups, with coastal lagoons and estuaries serving as a breeding ground. Reproductive activity peaks during the rainy season from April to September, likely to correspond to high abundances of prey species.
ous and potentially injurious to humans. The daisy stingray is caught by intensive artisanal
and small-scale commercial fisheries
occurring off the coasts of Senegal
, Ghana
, and Côte d'Ivoire
, and sold fresh, smoked, or dried and salted for human consumption. A wide variety of fishing gear is used, including longlines, bottom trawls, trammel nets, gillnet
s, traps
, beach seines, and hook-and-line. Habitat degradation from agricultural runoff and industrial development may also threaten its population. Once common, catches of this slow-reproducing ray have become scarce in recent years, leading the International Union for Conservation of Nature (IUCN) to assess it as Endangered. The daisy stingray has not yet been the target of any specific conservation schemes.
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
Stingray
The stingrays are a group of rays, which are cartilaginous fishes related to sharks. They are classified in the suborder Myliobatoidei of the order Myliobatiformes, and consist of eight families: Hexatrygonidae , Plesiobatidae , Urolophidae , Urotrygonidae , Dasyatidae , Potamotrygonidae The...
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 shallow coastal waters along the coast of West Africa
West Africa
West Africa or Western Africa is the westernmost region of the African continent. Geopolitically, the UN definition of Western Africa includes the following 16 countries and an area of approximately 5 million square km:-Flags of West Africa:...
. This species typically grows to 60 cm (23.6 in) across and has a rounded pectoral fin disc and (in adults) a wide band of dermal denticles over its back. It is characterized by a greatly enlarged, nacre
Nacre
Nacre , also known as mother of pearl, is an organic-inorganic composite material produced by some mollusks as an inner shell layer; it is also what makes up pearls. It is very strong, resilient, and iridescent....
ous denticle in the middle of its back called a "pearl spine"; this feature is shared with the similar but much smaller 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), which has often been confused with this species. The daisy stingray feeds mainly on 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 exhibits aplacental viviparity, with litters of 1–4 young. Heavily pressured by fisheries and possibly habitat degradation, this once-common species is declining and has been assessed as Endangered by the International Union for Conservation of Nature (IUCN).
Taxonomy
British zoologist Albert Günther originally described the daisy stingray as Trygon margarita, in his 1870 Catalogue of the Fishes in the British Museum; subsequent authors synonymized the genus Trygon with Dasyatis. This species resembles, and is likely closely related to, the pearl stingray and the Niger stingrayNiger stingray
The Niger stingray or smooth freshwater stingray, Dasyatis garouaensis, is a species of stingray in the family Dasyatidae, native to rivers in Nigeria and Cameroon. Attaining a width of , this species can be distinguished by its thin, almost circular pectoral fin disk, slightly projecting snout...
(D. garouaensis), both also native to West Africa. Numerous scientific accounts of the daisy stingray have been confounded by confusion with the pearl stingray; this confusion dates back to the two West African specimens referenced in Günther's original description. In 1984, Leonard Compagno
Leonard Compagno
Leonard Joseph Victor Compagno is an international authority on shark taxonomy and the author of many scientific papers and books on the subject, best known of which is his 1984 catalogue of shark species produced for the Food and Agriculture Organization of the United Nations.-Career:*Ph.D,...
and Tyson Roberts identified one of them as a pearl stingray and designated the other as the 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 this species. The specific epithet margarita 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...
for "pearl
Pearl
A pearl is a hard object produced within the soft tissue of a living shelled mollusk. Just like the shell of a mollusk, a pearl is made up of calcium carbonate in minute crystalline form, which has been deposited in concentric layers. The ideal pearl is perfectly round and smooth, but many other...
", referring to the large tubercle on its back.
Distribution and habitat
The known range of the daisy stingray extends from SenegalSenegal
Senegal , officially the Republic of Senegal , is a country in western Africa. It owes its name to the Sénégal River that borders it to the east and north...
to the Democratic Republic of the Congo
Democratic Republic of the Congo
The Democratic Republic of the Congo is a state located in Central Africa. It is the second largest country in Africa by area and the eleventh largest in the world...
; records of it occurring as far as Mauritania
Mauritania
Mauritania is a country in the Maghreb and West Africa. It is bordered by the Atlantic Ocean in the west, by Western Sahara in the north, by Algeria in the northeast, by Mali in the east and southeast, and by Senegal in the southwest...
and Angola
Angola
Angola, officially the Republic of Angola , is a country in south-central Africa bordered by Namibia on the south, the Democratic Republic of the Congo on the north, and Zambia on the east; its west coast is on the Atlantic Ocean with Luanda as its capital city...
may have been mistakenly based on the pearl stingray. This bottom-dwelling species is found in marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
and brackish water
Brackish water
Brackish water is water that has more salinity than fresh water, but not as much as seawater. It may result from mixing of seawater with fresh water, as in estuaries, or it may occur in brackish fossil aquifers. The word comes from the Middle Dutch root "brak," meaning "salty"...
s with a salinity
Salinity
Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...
of 20–40 ppt. It favors sandy habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
s in shallow coastal waters to a depth of 60 m (196.9 ft), though most are found between 11 and 20 m (36.1 and 65.6 ft). This ray also reportedly frequents 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,...
s and estuaries; however, this also requires confirmation due to confusion with the pearl stingray.
Description
The pectoral fin disc of the daisy stingray is moderately thin and rounded, measuring about as wide as long. The leading margins of the disc are concave and converge at the pointed, slightly projecting tip of the snout. The eyes are medium-sized and followed by somewhat 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. There is a curtain of skin between the nares, with a fringed, subtly tri-lobed posterior margin; a pair of shallow grooves run from the skin flap to the corners of the bow-shaped mouth. There are 5 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 in a transverse row across the floor of the mouth, with the outermost pair set apart from the others. The tooth rows number 24–32 in the upper jaw and 28–36 rows in the lower jaw, and are 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 pelvic fins are short, with the tips projecting just past the disc margin.
The tail is longer than the disc and usually bears a single long, thin stinging spine on the upper surface. The tail is broad and flattened at the base, becoming slender and whip-like past the spine with a low dorsal keel and a well-developed ventral fin fold. There is a massive, circular pearl spine at the center of the disc. Young rays are otherwise smooth-skinned, while older rays over 20 cm (7.9 in) across gain a wide band of small, flattened, circular dermal denticles covering the median third of the back from between the eyes to the base of the tail, as well as small prickles covering the tail behind the sting. This ray is a plain grayish brown above, and whitish below. It reaches a maximum known disc width of 1 m (3.3 ft) and weight of 17 kg (37.5 lb), though most do not exceed a width of 60 cm (23.6 in). Females grow larger than males. Apart from being much larger, the daisy stingray can also be distinguished from the pearl stingray in having a relatively larger, round pearl spine, fewer tooth rows, and more pectoral fin radials (129–136 versus 113–127).
Biology and ecology
Little is known of the natural history of the daisy stingray. It feeds mainly on shrimpShrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
, 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, bivalves, and annelid worms. Off Nigeria
Nigeria
Nigeria , officially the Federal Republic of Nigeria, is a federal constitutional republic comprising 36 states and its Federal Capital Territory, Abuja. The country is located in West Africa and shares land borders with the Republic of Benin in the west, Chad and Cameroon in the east, and Niger in...
, some three-quarters of its diet consists of the shrimp
Shrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
Farfantepenaeus duorarum. Like other stingrays, this species is aplacental viviparous. Females bear litters of 1–4 pups, with coastal lagoons and estuaries serving as a breeding ground. Reproductive activity peaks during the rainy season from April to September, likely to correspond to high abundances of prey species.
Human interactions
The tail spine of the daisy stingray is reportedly highly 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 and potentially injurious to humans. The daisy stingray is caught by intensive 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...
and small-scale commercial fisheries
Commercial fishing
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 pursue fish far into the ocean under adverse conditions...
occurring off the coasts of Senegal
Senegal
Senegal , officially the Republic of Senegal , is a country in western Africa. It owes its name to the Sénégal River that borders it to the east and north...
, Ghana
Ghana
Ghana , officially the Republic of Ghana, is a country located in West Africa. It is bordered by Côte d'Ivoire to the west, Burkina Faso to the north, Togo to the east, and the Gulf of Guinea to the south...
, and Côte d'Ivoire
Côte d'Ivoire
The Republic of Côte d'Ivoire or Ivory Coast is a country in West Africa. It has an area of , and borders the countries Liberia, Guinea, Mali, Burkina Faso and Ghana; its southern boundary is along the Gulf of Guinea. The country's population was 15,366,672 in 1998 and was estimated to be...
, and sold fresh, smoked, or dried and salted for human consumption. A wide variety of fishing gear is used, including longlines, bottom trawls, trammel nets, 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, traps
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...
, beach seines, and hook-and-line. Habitat degradation from agricultural runoff and industrial development may also threaten its population. Once common, catches of this slow-reproducing ray have become scarce in recent years, leading the International Union for Conservation of Nature (IUCN) to assess it as Endangered. The daisy stingray has not yet been the target of any specific conservation schemes.