Dive Dry with Dr. Bill

035: Electric Rays

When I was in kindergarten, I remember making a "warship" out of 2 x 4's in school. Instead of being satisfied with something that merely floated in the bathtub, I decided to enhance my design by nailing a string to its stern and attaching a bobby pin to the end of the string. After school I proudly walked home with my creation and showed it to my mother. She was busy talking over coffee with a neighbor, and told me to take it into the living room and play with it. I marched out there and decided it was time to test my handiwork.

I had seen my parents plug things into the wall sockets and, like our fan, they moved when plugged in. I proudly plugged the bobby pin into the wall plug and... ZOWIE! Not only did the boat move, I did too... bouncing back several feet due to the shock! I never forgot that experience and any time I need electrical work done at home, I call a real electrician!

There are some fish that you never forget either. One of these is the electric ray. The species in our region is the Pacific electric or torpedo ray. While I have not had the opportunity to photograph this particular species, I have photographed its southern relative, the bullseye electric ray found in the waters of the Gulf of California (see picture). ** The Pacific electric ray is found from British Columbia to the central Pacific coast of Baja California. It is most common from Pt. Conception south and may be found in waters down to 1,000 or even 1,500 feet. During the day they tend to rest on sandy or mud bottoms, occasionally near kelp beds. Electric rays feed primarily at night, swimming a few feet above the bottom and over reefs.

It is believed they hunt for prey by using their eyesight, ability to detect water motion and by sensing the electric field surrounding their prey. They swim above their potential food and stun it with an electric discharge that exceeds 45 volts according to Dr. Milton Love of UCSB, and may be much higher. Their favorite foods include kelp bass and northern anchovies.

The electric discharge is produced by two organs located on either side of their head on the central disk. Our electric ray reaches 4 1/2 feet in length, and they are generally fearless, even approaching divers underwater. In 1985 while working with the Cousteaus aboard their experimental windship Alcyone, one of the divers was zapped by a torpedo ray. Although Clay knew what the fish was, I don't think he was prepared for the shocking experience he had when he reached out to it! That was the end of his diving for a day or two. It was all caught on film so it made it into the television documentary we were working on about the Channel Islands for Cousteau's "Rediscovery of the World" series on TBS.

During the winter of 2002-03 I encountered another species, the bullseye electric ray, twice in the waters around Los Islotes (a small series of islets near La Paz). Both times I was able to slowly approach the ray and get good video footage without being zapped by it. Eventually it slowly swam away. Like me, it must have been a lover, not a fighter!

I have read that the bullseye electric ray can deliver an even more potent shock of up to 220 volts. This didn't surprise me since the electrical grids in many foreign countries operate at higher voltages than our 110 volts in the States. Maybe by using the voltage converters I take with me when traveling to foreign countries, I could throttle this species' high voltage down to something we Americans are more accustomed to! Come to think of it, even 110 volts was enough to do me in as a child. Maybe 12 volts would be more tolerable.

© 2003 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 49, 10:00 AM and 5:00 PM weekdays.

Image caption: A bullseye electric ray in the waters of Los Islotes,
Gulf of California, Mexico

This document maintained by Dr. Bill Bushing.
Material © 2003 Star Thrower Educational Multimedia