 = Diamond stingray = 
 
 The diamond stingray ( Dasyatis dipterura ) is a species of stingray in the family <unk> . It is found in the coastal waters of the eastern Pacific Ocean from southern California to northern Chile , and around the <unk> and Hawaiian Islands . This bottom @-@ dweller generally inhabits sandy or muddy flats near rocky reefs and kelp forests , to a depth of 30 m ( 98 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 tubercles 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 <unk> stingray ( D. <unk> ) . 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 <unk> mainly on burrowing invertebrates and small bony fishes , which are extracted from the bottom via <unk> or digging . This species is aplacental viviparous : once the embryos exhaust their yolk supply , they are nourished by histotroph ( " uterine milk " ) produced by the mother . Females bear 1 – 4 <unk> 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 <unk> against fishing pressure . It is caught for food by <unk> 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 <unk> . Though <unk> towards humans , the diamond stingray 's long , venomous tail spine is potentially dangerous . 
 
 = = Taxonomy and phylogeny = = 
 
 In 1880 , the diamond stingray was described twice by three American <unk> : as <unk> <unk> by David Starr Jordan and Charles Henry Gilbert in Proceedings of the United States National Museum , and as <unk> brevis by Samuel Garman in Bulletin of the Museum of Comparative <unk> . Jordan and Gilbert 's account was published in May while Garman 's was published in October , making <unk> ( feminine dipterura ) the correct name as it was published first . However , when Garman synonymized the two in 1913 he <unk> gave precedence to brevis , leading to long @-@ standing confusion . Both <unk> and <unk> 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. <unk> ) with D. dipterura in 1913 , which has since been followed by most authors but requires more study for confirmation . 
 The species <unk> were collected from San Diego Bay , California . The specific epithet dipterura is derived from the Latin di ( " two " ) , <unk> ( " wing " ) , and <unk> ( " tail " ) , referring to the fin folds on both sides of its tail . Rat @-@ tailed stingray is a former common name for this species . Lisa <unk> 's 2001 phylogenetic analysis , based on morphology , determined the diamond stingray and the <unk> 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. <unk> ) . 
 
 = = Distribution and habitat = = 
 
 The diamond stingray is found in the eastern Pacific Ocean from southern California to northern Chile , as well as around the <unk> 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 <unk> 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 <unk> , often near rocky reefs or kelp forests . Off southern California , it usually occurs from the <unk> zone to a depth of 7 m ( 23 ft ) during the summer , shifting to depths of 13 – 18 m ( 43 – 59 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 ( 10 – 100 ft ) . On the other hand , this species has been reported from as far down as 355 m ( 1 @,@ 165 ft ) off Hawaii , which if accurate would suggest that it utilizes a much greater range of depths than previously realized . 
 
 = = Description = = 
 
 The diamond stingray <unk> 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 <unk> 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 spiracles ( 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 ( <unk> @-@ 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 , <unk> 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 <unk> stingray ( D. <unk> ) , which shares most of its range . However , the tail is often damaged , in which case <unk> the two species in the field becomes all but impossible . Young rays have completely smooth skin , while adults develop a row of low tubercles along the midline of the back , flanked by two shorter rows on the " shoulders " . The tail also becomes covered in <unk> . This species is a uniform olive to brown to gray above , darkening to black on the tail , and off @-@ white below . 
 
 = = Biology and ecology = = 
 
 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 crustaceans , molluscs , and other invertebrates , as well as small bony fishes ; its powerful jaws and <unk> @-@ 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 in ) across , that had <unk> herself on at least 30 small crabs . In the Bahía Magdalena <unk> complex , Baja California Sur , its most important source of food are pea crabs , followed by the razor <unk> <unk> <unk> , 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 <unk> 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 <unk> ( <unk> <unk> ) , <unk> <unk> ( <unk> <unk> ) , <unk> <unk> ( <unk> <unk> ) , spinster <unk> ( <unk> <unk> ) , and long @-@ spine <unk> ( <unk> <unk> ) , which take advantage of the invertebrates stirred up by the ray 's activities . Known parasites of this species include the <unk> <unk> <unk> , A. <unk> , A. <unk> , and A. <unk> , <unk> <unk> , <unk> <unk> , and <unk> <unk> , the <unk> <unk> <unk> and <unk> <unk> , and the <unk> <unk> <unk> . 
 Like other stingrays , the diamond stingray is aplacental viviparous : the embryos are initially nourished by yolk , and later by histotroph ( " uterine milk " , rich in proteins and <unk> ) 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 <unk> per year . <unk> and mating occurs in late summer from July to August , but due to a ten @-@ month period of either sperm storage or <unk> ( wherein the embryo becomes <unk> ) , embryonic development does not begin until the following year and is completed within 2 – 3 months . <unk> 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 ( 17 – 19 in ) across and 7 years of age , while females grow slower still , reaching maturity at around 57 – 66 cm ( 22 – 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 , venomous 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 <unk> ; the pectoral fins or " wings " are sold fresh or <unk> and salted . The International Union for Conservation of Nature ( IUCN ) notes that the diamond stingray 's low reproductive <unk> renders it susceptible to population depletion , but currently lacks enough biological and fishery data to assess it beyond Data <unk> overall , or in the U.S. , Central , and South American parts of its range . 
 In Mexico , the diamond stingray is one of the most important components of Pacific <unk> 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 <unk> 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 . <unk> <unk> are the main fishing gear employed ; both adult and juvenile rays easily become entangled in the <unk> 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 <unk> , and in fish traps . In the future , habitat degradation from increasing numbers of shrimp farms 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 . 
 
 