The order Torpediniformes is a group of cartilaginous fishes distinguished by their ability to generate electrical discharges. Commonly known as electric rays, the species of this order have in common the presence of specialized electrical organs that they use to stun their prey or defend themselves against predators. The scientific name ‘Torpediniformes‘ derives from the Latin ‘torpere‘ meaning to paralyze or hinder, in reference to their ability to produce electricity. These fish mainly inhabit sandy and muddy seabeds of temperate and tropical seas, and are widely distributed in the Atlantic, Indian and Pacific Oceans, as well as in the Mediterranean Sea. Some species are found in shallow waters, while others inhabit deeper areas.
In terms of morphology, members of the order Torpediniformes have flattened disc-shaped bodies, similar to other rays, but with unique characteristics. The body disk, formed by the fusion of the pectoral fins, is oval or circular, and its length can vary considerably among species, from a few centimeters to more than a meter in large species. A distinctive feature is the presence of electrical organs on the side of the body behind the head, which are formed by specialized cells called electroplasts. The tail is generally short and robust, with one or two small dorsal fins and a well-developed caudal fin. The coloration of these rays is usually brown, gray or yellowish, which helps them camouflage themselves on the seabed.
In terms of feeding habits, electric rays are carnivorous and feed mainly on small fish, crustaceans and mollusks. They are nocturnal hunters and use their electric organs to generate shocks that stun or paralyze their prey before ingesting them. When lurking on the seafloor, they usually bury themselves partially in the sand, waiting for their prey to approach. Once they locate their prey by electroreception, a sensory ability that detects electrical fields in the water, they emit an electric shock to immobilize it. After capturing their prey, they consume it using their ventral mouthparts.
This group of electric rays includes some 69 known species, divided into two main families:
- Torpedinidae: includes the larger electric rays such as those of the genus Torpedo
- Narcinidae: includes the smaller electric rays, commonly known as narcas
Electric rays have been the subject of study in various scientific fields due to their ability to generate electricity, which has sparked interest in the fields of biomedicine and neurobiology. In ancient times, some civilizations used electric stingrays to treat headaches or neurological diseases, taking advantage of their discharges as a rudimentary form of electrotherapy.
In addition to their historical use in medicine, electric stingrays play an important role in the marine ecosystem, controlling small prey populations. Despite their defensive capabilities, they are vulnerable to overfishing and habitat degradation, which has led to some species being threatened or endangered.