It’s True: Electric Eels Can Leap From the Water to Attack | National Geographic

The eel has this challenge that when it gives off electricity, that electricity is distributed around the eel in the water. A predator that is on land and reaching into that pool may not receive very much of a shock.

You've got this tale from 1800 about Alexander Von Humboldt, who went to South America to collect electric eels and do experiments on their electrical output.

The electric eels went on the offensive and pressed themselves against the horses while shocking them. It shows an eel having essentially leapt out of the water and pressing its chin against the belly of one of the horses.

If you reach in with one hand and touch an electric eel while it's giving off its high voltage, you don't feel very much. If the eel starts to come out of the water with its positive end, that the chin touching the predator, the voltage increases.

As the eel ascends, the current path that would normally take the electricity back to the water is getting more and more resistive as the eel ascends the conductor. So the eel is leveraging this basic principle to sort of turn up the volume on the attack as the eel emerges out of the water.

Each time you see one of those LEDs flash, those would be the nerve fibers firing in that predator. If I use an insulated glove and then put a conductive glove, I can essentially demonstrate this on a small scale.

Essentially, what you've got there is an electric fence in the form of a fish.