The spinytail skate - also known as the spinetail ray - is differentiated from other northwest Atlantic skates by the presence of the single row of relatively large, thorn-like spines beginning slightly in front of the axils of the pelvic fins and extending along the midline of the tail, and by the one large spine separating the two dorsal fins, which have ragged edges. The upper surface of the disc is spine-free but rough with prickles, and mature males have 3 or 4 rows of spines on the outer parts of their pectoral fins. The ventral surface of the disc is smooth, and the mucous pores are not blackish. The spinytail skate also has a pointed snout; single-cusped teeth; a short caudal fin; bilobed pelvics, and relatively small claspers (in the case of mature males). The colour of the dorsal surface is uniformly pale brown or bluish-gray, with the posterior edges of the pectorals being slightly paler. The ventral surface is white with irregularly distributed sooty markings around the edges of the pectorals.
The spinytail skate grows to a maximum total length of 152 to 172 cm.
The spinytail skate is primarily a coldwater skate, and is therefore reported infrequently from Canadian Atlantic waters. In the western Atlantic it is captured on the Greenland side of Davis Strait, and is occasionally taken off southeast Nova Scotia to the eastern slope of Georges Bank. It also reportedly occurs in waters off the coast of NewFoundland as well as in the Gulf of St Lawrence. In the eastern Atlantic, the spinytail skate occurs around Iceland and in the Barents Sea.
This skate is usually captured at depths below 165 m where the water temperature ranges from -1.5 to 3.3°C. It has been captured at depths of 1463 m.
The diet of the spinytail skate is not fully known. However, the stomachs of specimens captured in west Greenland contained capelin and thorny skate.
Oviparous. Fecundity assumed to be less than 100 individuals.
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