Behind each eye sits an organ built from columns of electrocytes, flattened cells derived from branchial muscle. Each cell generates only a small potential, but hundreds are stacked face to face in a column, and thousands of columns are arranged side by side, so the voltages add in series while the currents add in parallel.
The Atlantic torpedo is the strongest of the electric rays, with discharges reported around 220 volts. The ray uses them to stun prey, wrapping its disc around a fish and firing a burst, and to deter attackers. Discharges weaken with repeated use and need time to recover.
The name runs from the ray to the weapon, not the other way. Latin torpere means to be numb or stiff, which describes the effect on a handler; the self-propelled naval torpedo was named after the fish in the nineteenth century.