Lesson 1
Living batteries
Electric eels live in rivers in South America. (Fun fact: they're not really eels! They're a kind of knifefish.)
Most of an electric eel's body, about 80 percent of it, is filled with special cells called electrocytes (ee-LEK-troh-sites). These cells are flat, like pancakes, and they're stacked in long rows like batteries in a flashlight.
- Each electric cell makes only a tiny bit of electricity.
- But thousands are lined up in a row, so their zaps add together into one big shock.
Wow!
One kind of electric eel was measured making 860 volts. That's more than 7 times the electricity in a wall outlet in a home in the United States!
Lesson 2
How a cell makes electricity
Here's a surprise: all your cells use tiny bits of electricity, especially your nerve cells! Cells make electricity by moving tiny salty bits, called ions, in and out.
Electric cells started out long, long ago as muscle cells. Over time they changed into cells that are super good at making electricity, instead of squeezing.
- When the eel's brain says "zap!", a nerve sends the signal to all the electric cells.
- They all fire at the same moment, and the shock flows out into the water.
Try this
Scroll up to the 3D eel and press Zap! to see the signal travel and the cells light up together.
Lesson 3
What eels use electricity for
- Hunting. A big zap stuns fish so the eel can gulp them down.
- Staying safe. Few animals want to bother an electric eel!
- Sensing. Electric eels have poor eyesight. They send out weak electric pulses and feel how the electricity bounces around, which helps them find their way in muddy water.
Other animals have electric cells too, like torpedo rays and electric catfish.
Wow!
Electric eels can leap partly out of the water and press their chin against an animal to give an extra-strong shock. Never touch one!