Pincushion ray
A heavily armored freshwater stingray with thorny defenses.
The pincushion ray, also called the thorny freshwater stingray (Fontitrygon ukpam), is a poorly understood member of the Dasyatidae family inhabiting West and Central African rivers and lakes. This ray has a thick, rounded body that can reach 1.2 meters across. Unlike most stingrays, its tail spine is either very small or missing entirely. Instead, adults defend themselves with a dense covering of large, sharp thorns on their back and tail. Because it has been rarely seen since its first description, the International Union for Conservation of Nature (IUCN) lists it as Critically Endangered.
**Taxonomy** John Alexander Smith first described this ray in 1863, publishing his findings in the Proceedings of the Royal Physical Society of Edinburgh. He used the local name *ukpam* for the species. Noticing that the ray had a single, reduced tail spine—a condition he saw as halfway between the spineless *Urogymnus* and the single- or multiple-spined *Trygon* (now *Dasyatis*)—Smith created the genus *Hemitrygon* (from Greek *hemi*, meaning "half"). Later scientists have placed it in either *Dasyatis* or *Urogymnus*.
**Distribution and habitat** The pincushion ray is one of only two freshwater stingrays in Africa, the other being the Niger stingray (*F. garouaensis*). It has been recorded in the Old Calabar River (Nigeria), the Sanaga River (Cameroon), Lake Ezanga and the Ogooué River (Gabon), and the Congo River near Binda (Democratic Republic of the Congo). Smith’s original account also mentioned it in brackish water at the Old Calabar mouth, but no modern records confirm whether it can tolerate saltwater. If it is euryhaline, it might move between river systems through coastal waters.
**Description** This ray has a slightly pointed snout and a very thick, oval pectoral fin disk that is a bit longer than wide, with 142–148 internal rays on each side. Its large eyes have a small projection on the upper eyelid, followed by prominent spiracles. The slightly arched mouth contains many rounded teeth set close together: 38–40 rows in the upper jaw and 38–48 in the lower jaw. Five papillae line the mouth floor. The pelvic fins are rounded and fused along their inner edges. The whip-like tail, which has a narrow fin fold underneath, is about three times the body length in juveniles but becomes relatively shorter with age.
Quick Facts
- Genus
- Fontitrygon
- Species
- ukpam
Facts from the source article.
Lore & Background
John Alexander Smith scientifically described the pincushion ray in 1863, naming it ukpam after the local indigenous name for freshwater stingrays. He placed it in the genus Hemitrygon, from the Greek hemi meaning 'half', because he saw its single reduced tail spine as intermediate between the spineless Urogymnus and the spined Trygon (=Dasyatis). Subsequent authors have regarded it as either a member of Dasyatis or Urogymnus.
The pincushion ray has a slightly projecting snout, an oval very thick pectoral fin disk with 142–148 internal rays on each side, large eyes with a projection on the upper eyelid, and prominent spiracles. Its mouth contains 38–40 tooth rows in the upper jaw and 38–48 in the lower jaw, with five papillae on the floor. The tail is whip-like with a narrow fin fold underneath, about three times the body length in juveniles and becoming relatively shorter with age. Some individuals have a small grooved spine near the tail base, averaging 5.6 cm in males and 4.6 cm in females; adult spines have around 46 serrations. Newborns have smooth skin, while older fish develop numerous large thorny dermal denticles over the upper surface. Dorsal coloration is uniform dark brown or gray-brown, the tail nearly black past the base, and the underside white with a broad dark edge.
According to Smith's original account, the pincushion ray defends itself by striking with its thorn-covered tail, inflicting 'severe and even dangerous wounds'. Its diet consists mainly of small eels. Like other stingrays, it is aplacental viviparous, with a report of a female gestating two offspring. One recorded female 45.2 cm across from the Sanaga River was reproductively immature.
Reader's Guide
The pincushion ray is one of only two freshwater stingrays in Africa, the other being the Niger stingray (F. garouaensis). It has been reported from the Old Calabar River in Nigeria, the Sanaga River in Cameroon, Lake Ezanga and the Ogooué River in Gabon, and the Congo River near Binda in the Democratic Republic of the Congo. Smith's original account also described it as occurring in brackish water at the mouth of the Old Calabar, but whether it is euryhaline has yet to be corroborated by modern records. If it can tolerate higher salinities, it may be able to move between river systems via coastal waters. During the 19th century, the pincushion ray reportedly occurred with 'considerable abundance' in the Old Calabar River. However, in modern times it is represented by fewer than 10 museum specimens and a handful of additional specimens recently caught from Gabon. Given that it lives in a heavily populated region, this species may have been over-exploited by intensive artisan fishing; Smith noted that it was considered a 'great delicacy' by locals and hunted with barbed spears. It may also be affected by habitat degradation. The rarity of this species and the substantial threats it may face have led the IUCN to assess it as Critically Endangered.
Did You Know?
- The pincushion ray uses stout thorns on its back and tail for defense instead of a long tail spine.
- John Alexander Smith described the species in 1863 and coined the genus Hemitrygon (meaning 'half') for it.
- Smith recorded specimens measuring 1.2 m across and 3 m long that required four men to lift.
Frequently Asked Questions
What is a pincushion ray?
The pincushion ray (Fontitrygon ukpam) is a thick-bodied freshwater stingray in the Dasyatidae family, originally described by John Alexander Smith in 1863. It is a rounded, heavily built ray found in rivers and lakes across West and Central Africa.
How does a pincushion ray defend itself?
Instead of a prominent tail spine like most stingrays, the pincushion ray relies on a dense covering of large, sharp thorns across its back and tail. Adults are essentially armored in spines, making them very difficult for predators to bite or handle.
How big does a pincushion ray get?
Adults can span up to 1.2 meters (roughly 4 feet) across their disk, with a total body length reaching about 3 meters (10 feet). That places it among the larger freshwater rays in its African range.
Why is the pincushion ray listed as Critically Endangered?
The species has been extremely rarely observed since its 19th-century description, so very little is known about its population size or ecology. The IUCN assigns it Critically Endangered status because of this persistent scarcity of sightings combined with threats to its freshwater habitat.
Where does a pincushion ray live?
This ray is a strictly freshwater species, inhabiting rivers and lakes throughout West and Central Africa. It does not occur in marine or brackish environments, which distinguishes it from many other ray families.
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