Like other members of its family, the Pacific electric ray produces powerful electric shocks for attack and defense. Its paired electric organs are derived from muscle and comprise approximately 15% of its total weight, consisting of many thousands of jelly-filled "electric plates" stacked hundreds-high into vertical hexagonal columns. These columns function essentially like batteries connected in parallel; a large adult ray can generate some 45 volts of electricity with a power output of one kilowatt, due to low internal resistance. The electric organs discharge direct current in pulses, each lasting 4–5 ms. When attacking prey, in the first few moments the ray normally produces pulses at a rate of 150–200 per second, slowing down over time. Over a thousand pulses may be produced in all, depending on how long it takes for the prey to be subdued. The pulse rate increases with water temperature.