 The pelvic fins are small and narrow. The thin, rapidly tapering tail is about equal to the disc in length and has an almost cylindrical cross-section, without fin folds. The tail also has no venomous stinging spine, unlike other members of the family. A dense patch of flattened, heart-shaped dermal denticles covers the center of the disc and extends onto the tail. Larger individuals additionally have numerous tall, sharp thorns over the entire upper surface of the disc. The porcupine ray is plain light to dark gray or brown above, darkening to blackish towards the tail tip, and white below. This large species grows to at least 1.2 m (3.9 ft) across and 2.2 m (7.2 ft) long, and may reach 1.5 m (4.9 ft) across.
