Porcupine Ray

The porcupine ray (Urogymnus asperrimus) is a rare species within the Dasyatidae family, characterized by its unique morphology and behavior. This demersal species is located throughout the tropical Indo-Pacific region and along parts of the West African coast. It typically resides in sandy, coral rubble, and seagrass environments in shallow waters up to a depth of 30 meters (100 feet). With a robust physique, the porcupine ray has a disc measuring between 1.2 and 1.5 meters (3.9 to 4.9 feet) across, featuring a nearly circular and unadorned pectoral fin disc, and is distinguished by its slender tail, which lacks the fin folds common in other stingrays. Notably, it is the only species in its family that does not possess a venomous sting, yet it can defend itself effectively using the numerous large, sharp thorns covering its disc and tail.

The porcupine ray's diet primarily consists of benthic invertebrates and bony fishes, which it excavates from the sea floor. It demonstrates aplacental viviparity, with the developing embryos receiving nourishment through histotroph, or "uterine milk," provided by the mother. Historically, the species has been valued for its tough skin, used in producing shagreen leather, which was applied to both practical and decorative items such as sword hilts and shields. Incidentally captured by coastal fisheries, its thorns necessitate careful handling, limiting its commercial viability. Unchecked fishing practices have contributed to a decline in population, prompting the International Union for Conservation of Nature to classify it as Vulnerable.

Despite its broad distribution, the porcupine ray is less common than other stingrays occupying similar habitats. Its geographical range includes the 🌊 Indian Ocean, from 🇿🇦 South Africa and the Arabian Peninsula to Southeast Asia and the Ningaloo Reef off Western Australia, encompassing regions such as 🇲🇬 Madagascar, the 🇸🇨 Seychelles, and 🇱🇰 Sri Lanka, and extending into the eastern Mediterranean via the Suez Canal (🇪🇬 Egypt). In the 🌊 Pacific Ocean, its presence spans 🇮🇩 Indonesia, 🇵🇬 New Guinea, the 🇵🇭 Philippines, the Gilbert Islands, 🇫🇯 Fiji, and Heron Island off Eastern 🇦🇺 Australia. It also inhabits the eastern Atlantic off West Africa, in countries such as 🇸🇳 Senegal, Guinea, and Côte d'Ivoire, favoring coastal depths of 1 to 30 meters (3 to 100 feet) and thriving in sandy, coral, and seagrass environments.

Morphologically, the porcupine ray is characterized by an ovate, thick pectoral fin disc, rounded snout, small eyes preceded by large spiracles, and a distinctive, skin curtain overhanging the mouth. The mouth is equipped with multiple papillae and large tooth rows, complemented by five pairs of gill slits on its ventral side. Additionally, small pelvic fins, a cylindrical, tapering tail without fin folds, and extensive dermal denticle coverage are key features. Larger individuals bear numerous prominent thorns. Typically, this species exhibits a plain gray-brown coloration above, transitioning to blackish at the tail, with a lighter underside, and can grow to notable dimensions of at least 1.2 meters (3.9 feet) in width and 2.2 meters (7.2 feet) in total length, potentially reaching 1.5 meters (4.9 feet) across.

Behaviorally, the porcupine ray may rest motionless on the seabed or within caves and sometimes aggregates in groups, as observed at Ningaloo Reef. Its diet mainly includes sipunculids, polychaete worms, crustaceans, and bony fishes, with feeding behavior involving deep sediment excavation. Known parasites affecting this species include tapeworms and various nematodes and monogeneans. Juvenile rays often inhabit mangrove forests, with sexual maturity occurring at around 90 to 100 centimeters (35 to 39 inches) across for males and females, respectively. Although lacking venom, the porcupine ray can harm humans with its sharp thorns and is noted for its tolerance to close underwater proximity. Historically, its skin was fashioned into shagreen leather, applied to weapon grips and decorative uses in various cultures. Presently, bycatch in fisheries, along with anthropogenic threats such as habitat loss and resource depletion, contribute to its declining population, necessitating conservation measures as outlined by its Vulnerable status.