Marbled Torpedo

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.

Widely distributed in the eastern Atlantic Ocean, the marbled electric ray is found from Scotland and the southern North Sea southward to the Cape of Good Hope, and north at least as far as Durban, likely further. South Africa. In addition it is present in the Mediterranean Sea, with higher densities in western areas. It prefers temperatures cooler than 20 °C (68 °F). This species is typically found at depths of 10–30 m (33–98 ft) off Britain and Ireland, 20–100 m (66–328 ft) off Italy, and down to 200 m (660 ft) off Tunisia. It has been recorded from as deep as 370 m (1,210 ft). The marbled electric ray tends to be found deeper than the common torpedo (T. torpedo), which shares the southern portion of its range.

The marbled electric ray is an ambush predator that employs electricity to capture prey. Vision is of little importance in hunting, as the ray's eyes are often obscured as it lies buried on the bottom. Instead, it likely relies on the mechanoreceptors of its lateral line, as it only attacks moving prey. The electroreceptive ampullae of Lorenzini may also contribute to prey detection.

Solitary and slow-moving, the marbled electric ray may remain motionless for several days at a time. It is more active at night and spends much of the day buried in sediment with only the eyes and spiracles showing. Consistent with its sluggish nature, the marbled electric ray has a low blood oxygen carrying capacity and heart rate (10–15 beats/min), and consumes less oxygen than other sharks and rays of similar size. It is highly tolerant of being deprived of oxygen (hypoxia), allowing it to cope with deoxygenated bottom waters or being stranded in small pools by the falling tide. The ray stops breathing entirely when the oxygen partial pressure in the water drops below 10–15 Torr, and can survive such a state for at least five hours.

The shock delivered by the marbled electric ray can be painful but is seldom life-threatening, although there is a danger of a shocked diver becoming disoriented underwater. Its electrogenic properties have been known since classical antiquity, leading it and other electric fishes to be used in medicine. The ancient Greeks and Romans applied live rays to those afflicted with conditions such as chronic headaches and gout, and recommended that its meat be eaten by epileptics.