Pteroplatytrygon
The only stingray that lives in the open ocean.
The pelagic stingray, *Pteroplatytrygon violacea*, is the only member of its genus and belongs to the family Dasyatidae. It stands out among stingrays for living almost its entire life in the open ocean rather than on the seabed. Its pectoral fin disc is wedge-shaped and much wider than it is long, and its coloration is a uniform violet to blue-green. Both sexes have pointed teeth, and the tail is whip-like with an exceptionally long spine. The disc typically reaches a width of 59 cm (23 in). This species is found worldwide in waters warmer than 19 °C (66 °F) and migrates seasonally, spending summers closer to continental shelves and at higher latitudes. It usually stays in surface waters down to about 100 m (330 ft). Because of its midwater lifestyle, it swims by flapping its pectoral fins, unlike bottom-dwelling stingrays that undulate the disc margins.
The diet consists of free-swimming invertebrates and bony fish. It hunts actively, using its pectoral fins to trap and move prey to its mouth, and will take advantage of seasonal opportunities like spawning squid. Like other stingrays, it is aplacental viviparous: embryos are first sustained by yolk, then by histotroph ("uterine milk"). Gestation lasts only 2–4 months, and females can produce two litters per year, each with 4–13 pups. Birthing usually happens in warm equatorial waters, except in the Mediterranean, with timing varying by region. Rarely seen except by fishery workers, this stingray can inflict severe or even fatal wounds with its tail spine. It is caught as bycatch throughout its range, has little economic value, and is usually discarded, often with high mortality. However, evidence suggests its numbers are increasing, possibly because heavy fishing has reduced its natural predators and competitors, such as sharks. Combined with its global distribution and prolific reproduction, this has led the International Union for Conservation of Nature (IUCN) to classify it as Least Concern.
The species was first described by French naturalist Charles Lucien Bonaparte in 1832 in the third volume of *Iconografia della fauna italica per le quattro classi degli animali vertebrati*. He named it *Trygon violacea*, from the Latin *viola* ("purple"), using two specimens collected off Italy as syntypes. The genus *Trygon* has since been merged with *Dasyatis*.
Quick Facts
- Genus
- Pteroplatytrygon
- Species
- violacea
Facts from the source article.
Lore & Background
The pelagic stingray was originally described by French naturalist Charles Lucien Bonaparte in 1832 as Trygon violacea. American zoologist Henry Weed Fowler later placed it in the subgenus Pteroplatytrygon, which was elevated to full genus by subsequent authors, though some taxonomists dispute whether it is distinct enough from Dasyatis. Lisa Rosenberger's 2001 phylogenetic analysis found it to be a basal member of its family, sister to a clade containing Pastinachus, Dasyatis, and Indo-Pacific Himantura species.
This species has a worldwide distribution in waters warmer than 19 °C, between latitudes 52°N and 50°S, and migrates seasonally following warm water masses. In the northwestern Atlantic, it is found in or near the Gulf Stream from December to April and moves north near the continental shelf from July to September. Two Pacific populations migrate: one from near Central America to California, and another from the central Pacific to Japan and British Columbia.
Unlike bottom-dwelling stingrays, the pelagic stingray swims by flapping its pectoral fins like eagle rays, which improves cruising efficiency in open water. It is an active hunter of free-swimming invertebrates and bony fishes, using its pectoral fins to trap food. It is aplacental viviparous, with females bearing two litters of 4–13 pups per year after a short gestation of 2–4 months, typically birthing in warm water near the equator.
Reader's Guide
The pelagic stingray is significant as the only stingray adapted to a pelagic lifestyle, exhibiting unique morphological and behavioral traits such as oscillatory fin swimming, reduced electroreceptor density on its underside, and reliance on vision for hunting. Its uniform violet to blue-green coloration and ability to exude thick black mucus when handled are distinctive. The species is rarely encountered except by fishery workers, but can inflict severe or fatal wounds with its extremely long tail spine.
Caught as bycatch throughout its range, it has little economic value and is usually discarded, often with high mortality. However, evidence suggests its numbers are increasing, possibly due to heavy fishing of its natural predators and competitors such as sharks. Combined with its global distribution and prolific life history (short gestation, multiple litters per year), the IUCN has assessed it as Least Concern. The species also holds taxonomic interest due to ongoing debate over its placement within or separate from the genus Dasyatis.
Did You Know?
- The pelagic stingray is the sole member of its genus Pteroplatytrygon.
- It can detect an electric field of well under 1 nV/cm at a distance of up to 30 cm.
- Females may bear two litters of 4–13 pups per year, with a gestation period of only 2–4 months.
- When captured, it exudes a thick black mucus that covers its body.
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