Like slippery Pokemon, electric eels can produce shocks strong enough to incapacitate large predators. But where do these electric fish get the power to generate such high-voltage attacks?

In a recent video, TED-Ed explains the volatile biology at play. Electric fish like electric eels (which are more closely related to catfish than actual eels) all contain at least one electric organ. This organ is packed with disc-shaped cells called electrocytes. These cells naturally release sodium and potassium ions which create a positive charge inside the cells and a negative charge outside them. But when electric fish send signals from their brains to these organs, it opens up the cells' ion channels, allowing the ions to re-enter. The result is an electrocyte with a positive interior and a negative exterior on one side and a negative interior and a positive exterior on the other—basically a biological battery. Once these cells are charged up, fish can use them to disrupt nearby electric signals, detect other fish, and even paralyze prey.

Fish aren’t the only animals that use electricity to their advantage. The oriental hornet, for example, makes electricity out of sunlight, while some spiders harvest charged particles by coating their webs in electrostatic glue.

[h/t TED-Ed]