This week I wrote my New York Times column about one of those remarkable studies that makes you realize how little we understand about the natural world. Ken Catania, a biologist at Vanderbilt University, performed some elegantly simple experiments that revealed that electric eels use electricity as a taser and as a remote control for their prey.
To read mostly straight-text accounts of the research, you can read my column, as well as fellow Phenom Ed Yong’s blog post. But the video that Catania filmed as part of his research is so interesting I thought offer a moving-pictures recap here.
Here’s what it’s like when an eel goes after a fish. The eel’s pulses of electricity are converted to sound. Basically, there’s an electric blast, a lunge, and it’s all over for the little fish.
But when Catania slowed down his video (he films it at 1000 frames a second), he could see that right after the eel starts sending out pulses, the fish just froze. Here are a couple examples. The red frames show when the eel is discharging electricity. The blast contracts all the fish’s muscles at once, causing the animal to freeze. It’s a natural taser.
Finally, here’s a movie that shows how the eel can flush out hidden prey. The fish here has its brain removed, and it’s tucked away in a walled-off recess in the eel’s tank. The barrier is made of agar, which allows electricity and waves to pass through.
The eel comes up, giving off short paired pulses of electricity. These pulses are like probes. Instead of immobilizing the fish, the pulses make the fish twitch. The waves set off by the twitch reveal its hiding place, and the eel comes in for a taser attack.
The full paper is here.