The specimen shown here is almost black, but many undulate rays are a much lighter yellow-brown with dark wavy bands lined by a twin row of white spots. Other white spots add to the complex patterning. The underside is white graduating to grey near the tip of the tail. The back of this ray is covered in small prickles, and there is a dense patch of prickles around the snout area. The dorsal fins are well separated and there are usually two dorsal spines between them.
Males have one row of median spines on each side, while females have two.
They feed of flatfish, squid, crustaceans and other bottom-dwelling creatures, and fish strips held on the bottom are most effective baits.