Overview
The Sailfin Roughshark (Oxynotus paradoxus) is one of the most distinctive and anatomically unusual deep-water elasmobranchs cruising the benthic continental slopes of the eastern Atlantic. Characterized by a high, humped triangular body and colossal sail-like dorsal fins armed with stout spines, this slow-moving deep-sea specialist possesses an unmistakable prehistoric silhouette.
Biology and Physical Characteristics
Oxynotus paradoxus is immediately recognized by its bizarre triangular cross-section, compressed flanks, and prominent lateral skin ridges. Its skin is exceptionally coarse, covered in large, spear-shaped dermal denticles that resemble sharp prickles. Its two dorsal fins are enormous, towering like tall triangular sails, each supported by an embedded spine tilted backward. Its head is short and blunted, housing large green-reflecting deep-water eyes and thick, fleshy, papillose lips surrounding small lanceolate upper teeth and blade-like lower teeth.
Behavior and Ecology
Operating as a slow-cruising benthic forager across deep continental margins (250 to 750 meters depth), the sailfin roughshark possesses an enormous, oil-rich liver that provides neutral buoyancy, allowing it to hover effortlessly over muddy sea bottoms. Studies indicate it feeds largely on the egg cases of other deep-water sharks and skates, using its specialized suction lips and blade-like teeth to pierce keratinous egg capsules and extract the nutritious embryos inside.
Conservation and Human Impact
Categorized as Vulnerable on the IUCN Red List, the Sailfin Roughshark suffers significant population pressure as accidental bycatch in commercial deep-water bottom trawl and gillnet fisheries operating along the European and African continental margins. Because it exhibits slow growth, late sexual maturity, and low fecundity (producing small litters of 10 to 16 pups), populations rebound slowly from bycatch mortality.
Interesting Factoid
The sailfin roughshark specializes in feeding on the tough egg cases (‘mermaid’s purses’) of other deep-sea skates and catsharks, sucking out the egg yolk through slits cut by its razor-sharp lower teeth.
Last updated: October 2026