Torpedo rays lent their shock to naval weapons
Electric rays of the order Torpediniformes can discharge between about 8 and 220 volts, depending on the species, to stun prey and fend off attackers. The genus Torpedo, from a Latin verb meaning to be numbed or stiffened, later lent its name to the undersea weapon.
Accounts put the group at roughly 60 to 69 species. They have a rounded disc of pectoral fins, a thick, flabby body with soft skin lacking denticles or thorns, and a stout muscular tail that does the swimming, unlike other rays that flap their fins. Mouth, nostrils and five pairs of gill slits sit underneath. These sluggish fish live from coastal shallows to at least 1,000 metres down, lying buried in sand and ambushing invertebrates and small fish.
Two kidney-shaped electric organs flank the head and send current from the lower surface to the upper. Each is a honeycomb of hexagonal columns, and every column stacks 500 to more than 1,000 plates of modified gill-arch muscle. In marine species these batteries are wired in parallel, while freshwater ones are arranged in series to push higher voltage through poorly conducting water. The Atlantic torpedo reaches 220 volts. Torpedo rays swallow big stunned prey whole, while narcinids pick small food from the bottom.
People knew the shock long before they understood it. Ancient Greeks used the rays to dull the pain of childbirth and surgery, and in Plato's Meno the title character says Socrates numbs people with his puzzling questions just as the torpedo fish does. The Roman physician Scribonius Largus prescribed the fish for headaches and gout in AD 46. Before electricity was understood, its power to numb fishermen seemingly without contact was cited as proof of occult forces in nature.
In the 1770s John Walsh and John Hunter described the torpedo's electric organs to the Royal Society, work that appears to have influenced Galvani and Volta, and in 1773 Henry Cavendish mimicked a ray with fish-shaped Leyden jars.
Source: Electric ray
