There are animals in the ocean that have the ability to generate electricity. So far, they are found only in fish, called electric fish. Electric rays are power generators and are found in tropical and subtropical waters.

The electric generator of the electric ray is derived from muscle tissue, and its generating site varies with species. The discharge of the generator is a continuous pulse discharge, high-frequency discharge up to 250-280 Hz, low-frequency discharge is only 10-20 Hz. Temperature has an effect on the discharge time, high temperature discharge time is short, low temperature discharge time is long. After the depletion of electrical energy, after a period of rest can restore the ability to discharge. Electrofishing generator voltage, with the different kinds of differences vary greatly, generally from a few volts to hundreds of volts, the highest up to nearly 1,000 volts. The single-fin electric skate and double-fin electric skate produced along the coast of Guangdong, China, is known as the "shock hand" by local fishermen, and the voltage is 37 to 45 volts.