Common torpedo

The pectoral fin disc of the common torpedo is almost circular in shape and about 1.3–1.4 times wider than long. The front margin of the disc is nearly straight. The two large, kidney-shaped electric organs are visible beneath the skin on either side of the head. The eyes are small and followed by spiracles of comparable size. The lateral and posterior rims of the spiracles bear small, low knobs, which diminish in size with age and may be indiscernible in larger individuals. On the "nape" behind the spiracles, there is a pair of prominent mucous pores. There is a wide, quadrangular flap of skin between the nostrils that almost reaches the mouth. The teeth are small and arranged in a dense quincunx pattern; each tooth has a single sharp cusp. There are around 22–24 and 20–22 tooth rows in the upper and lower jaws respectively. The five pairs of gill slits are placed on the underside of the disc. The pelvic fins are distinct from the disc and have rounded outer margins. The short and thick tail bears skin folds along either side and two dorsal fins on top. The first dorsal fin is slightly larger than the second. The well-developed caudal fin is triangular with blunt corners, and is approximately as long as the space between it and first dorsal fin. The skin is smooth and soft, entirely lacking dermal denticles. …

Native to the eastern Atlantic Ocean, the common torpedo occurs from the Bay of Biscay to Angola. It is present in the Mediterranean Sea as well, with higher densities in the western part of the Basin. A single record from Belgian waters was most likely erroneous. In European waters, it is encountered less frequently than other electric ray species. This species prefers warmer temperatures. It is rare north of the Mediterranean, and within the Mediterranean it is more common off North Africa than off southern Europe. The common torpedo is a bottom-dweller usually found close to shore at depths of 2–70 m (6.6–229.7 ft), though it has occasionally been reported from as deep as 400 m (1,300 ft). It inhabits soft-bottomed habitats such as sandy flats and seagrass beds.

As with other members of its family, the common torpedo can subdue prey and deter threats with strong electric shocks generated from a pair of large electric organs. Derived from muscle tissue, each organ is made up of 400–500 columns, each column constituting a stack of around 400 jelly-filled disks ("electroplaques"). The columns together essentially act as batteries connected in parallel. The discharge of the electric organs can reach 200 volts, and may occur singly or in bursts ("trains"). Experiments in vitro have found that the nerves innervating the electric organ essentially stop functioning at temperatures below 15 °C (59 °F). Winter water temperatures regularly drop below this threshold in the wild, suggesting the ray may not use its electric organs for part of the year, or has a yet-unknown physiological mechanism to adapt electric organ function to colder conditions. Solitary and nocturnal, the common torpedo spends much time resting on the sea floor, often buried in sediment. It is an ambush predator that pounces onto prey and stuns them with electricity, the process taking only a fraction of a second. Once the prey is immobilized, it is manipulated to the mouth with motions of the disc, and swallowed whole. Adults feed almost entirely on small benthic bony fishes, including soles, herring, mullet, gobies, goatfishes, porgies, dragonets, and jack mackerels. …