Overview
The Angular Roughshark (Oxynotus centrina), often delightfully referred to by Mediterranean fishermen as the ‘sea pig’ due to its peculiar snorting exhalations upon capture, is one of the most anatomically extraordinary sharks in the ocean. Sporting a compressed, triangular body cross-section, two colossal sail-like dorsal fins armed with venom-bearing spines, and coarse sandpaper-like dermal denticles, this sluggish bottom-dweller patrols deep continental shelves and slopes across the eastern Atlantic and Mediterranean.
Biology and Physical Characteristics
Oxynotus centrina possesses a high, humpbacked torso that is distinctly triangular in cross-section, flanked by prominent lateral ridges along the belly. Its skin is exceptionally coarse, covered in large, sharp, star-shaped dermal denticles that feel like coarse emery cloth. It bears two massive, triangular dorsal fins, each anchored by a heavy, partially concealed spine. Its head is flattened with large oval green eyes, fleshy papillose nostrils, and a small, circular mouth surrounded by thick fleshy lips containing blade-like lower teeth designed for sucking and piercing.
Behavior and Ecology
Sluggish and slow-swimming, the angular roughshark relies on neutral buoyancy provided by a massive, oil-rich liver to hover effortlessly just above the seabed. It exhibits one of the most specialized feeding niches among elasmobranchs: researchers have documented that it feeds extensively on the tough, leathery egg cases (mermaid’s purses) of skates and catsharks. Using its fleshy lips to create suction and sharp lower teeth to slit open egg capsules, it extracts and consumes the nutrient-dense embryos within.
Conservation and Human Impact
Classified as Vulnerable globally and Endangered in the Mediterranean by the IUCN, the angular roughshark has suffered steep population declines due to intensive commercial bottom trawling and gillnet fisheries. Because of its large dorsal fins and body thorns, it is highly prone to entanglement even when fishing gear is not aimed at sharks. While usually discarded as bycatch, survival rates are low, prompting calls for benthic protected marine zones and trawling exclusion corridors across historical Mediterranean nursery grounds.
Interesting Factoid
The angular roughshark has a triangular body like a sailing ship and specializes in hunting ‘mermaid’s purses’—slicing open the tough egg cases of skates to eat the embryos inside!
Last updated: October 2026