The Zapper Fish

Source: NOAA NMFS/WeirdFins - March 16, 2017 in Radio

The Zapper Fish
Photo: Kathy Dewet-Oleson, NOAA NMS Cordell Bank

Weird Gramma here with “WeirdFins,” all about strange stuff in the sea, and brought to you by the National Oceanic and Atmospheric Administration. Now, Salma in San Diego, California, wonders why a fish out there is called a torpedo, like the undersea explosive device. Well, Salma, “torpedo” is a Latin word meaning “stiffness,” or “numbness,” and that sure fits here. That torpedo, also called the Pacific electric ray, can generate a pretty good electric jolt that not only numbs the creatures it eats, but can also zap human swimmers when it feels threatened.

Electric rays are flat as a plate, with the mouth on the underside like stingrays, and they’re closely related to them. Like sharks, rays have a skeleton of cartilage instead of bone and use a series of gill slits to breathe. The Pacific electric ray grows to about 5 feet, about the size of a 12-year-old kid.

But I’ll bet you want to know how the torpedo’s electricity works. Well, this living zapper has masses of special cells in two organs behind its head that send out electric pulses. During the day, electric rays lie on the sandy bottom and feed by discharging bursts of electricity that stun fish swimming above them. At night, though, the rays are more active, using bursts of electricity to detect a prey animal, then lunging forward and paralyzing it with stronger electric jolts.

Can an electric ray kill you? Well, so far no human has been reported seriously injured by a ray’s electric shock. One measure of electricity is voltage and an electric ray’s discharge only reaches about 50 volts. It generally takes more than 500 volts to kill someone, although much lower voltage can stun a person or damage the heart.

You can see electric rays on the National Marine Fisheries Service WeirdFins link at www.nmfs.noaa.gov.

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