Marbled electric ray

The body of the marbled electric ray is soft and flabby, and entirely lacks dermal denticles. The thick pectoral fin disc is nearly circular and comprises about 59–67% of the total length; the paired kidney-shaped electric organs are visible beneath the skin, outside of the small eyes. Immediately posterior to each eye is a large, oval spiracle, which bears 6–8 long, finger-like projections on the rim that almost meet at the center. On the "nape" behind the spiracles, there are 5–7 prominent mucous pores. Between the nostrils, there is a quadrangular curtain of skin much broader than long, that almost reaches the small, arched mouth. The teeth are small with a single pointed cusp, and are arranged with a quincunx pattern into a pavement-like band in either jaw. The five pairs of gill slits are small and located beneath the disc. The two dorsal fins have rounded apexes and are placed close together; the base of each fin measures about two-thirds its height. The rear of the first dorsal fin base is located behind the rear of the pelvic fin bases. The second dorsal fin is only slightly smaller than the first. The short, robust tail has skin folds running along either side, and terminates in a large caudal fin shaped like a triangle with blunt corners. The upper surface has a dark mottled pattern on a light to dark brown background; some individuals are uniformly brown. The underside is plain off-white with darker fin margins. This species can grow up to 1 m (3.3 ft) long, though few exceed 36–38 cm (14–15 in) long for males and 55–61 cm (22–24 in) long for females.