Porcupine ray  (Urogymnus asperrimus)

Classified as Vulnerable (VU) on the IUCN Red List (1).

The porcupine ray is a highly distinctive, but little known species, which is named for the unusual thorny projections that are found on the upperside of its body (4) (5). This species has a thick, oval, disc-shaped body, a rounded snout and a long, whip-like tail, which does not possess the venomous barb that is characteristic of most members of the stingray family (Dasyatidae) (2). Instead, this species is protected from predators by its armoured body, which is covered with a mixture of large, sharp, conical thorns and smaller, pointed projections known as “denticles”. The young lack the thorns, but bear numerous large, flat denticles on the upper surface of the body (2) (5). The colouration of this species is brown to light grey above and white below, while the tail is blackish, becoming darker towards the tip (2) (5).

The porcupine ray is widely distributed throughout the Indian Ocean and the Indo-West Pacific, occurring from the coast of East Africa and the Red Sea, east as far as Marshall Islands and Fiji, and south as far as northern Australia (1) (4). It also occurs in tropical inshore waters of the East Atlantic, around central West Africa (4).

The porcupine ray is found on or near the sea-bed in shallow inshore water, often in association with coral reefs. It commonly occurs over sand or coral rubble substrates, frequently in caves (2) (4).

Little is known about the life history of the porcupine ray. It forages on and around the sea-bed for bottom-dwelling crustaceans, polychaete worms and fish (2) (4). Prey is grasped in the ray’s downward-facing jaws, which bear rows of flattened teeth capable of crushing hard, outer shells (6). Like other stingrays, the porcupine ray probably retains its eggs internally during development, so that once the egg hatch, the female gives birth to a litter of live young (6) (7).

Despite its large range, the porcupine fish is not regularly recorded by fisheries surveys, and is therefore believed to have a relatively small population. The population data that is available for this species indicates that it has undergone a significant population decline in parts of the centre of its range (1). The reason for this is unclear, as while the meat, skin and cartilage all have commercial value, the porcupine fish typically has little or no importance to fisheries. It is, however, often caught as bycatch in trawls and beach seines, which may be having a detrimental effect on its population. (2) (4).

There are no known conservation measures in place for the porcupine ray (1). Individuals have, however, been recorded in the Nature Reserve of the Glorieuses Islands (8), and given this species’ large range, it almost certainly occurs in other protected areas (9).

View information on this species at the UNEP World Conservation Monitoring Centre.

To learn more about the conservation of sharks and rays visit:

• Save Our Seas Foundation:
  www.saveourseas.com
• IUCN Shark Specialist Group:
  www.iucnssg.org
• Shark Research Institute:
  www.sharks.org
• Shark Trust:
  www.sharktrust.org