Electric Stingrays

Electric Stingrays There are fourteen known species of stingray that range from the Pacific coasts of California to British Columbia, all the way to various Atlantic locations. Stingrays are divided into two categories, based on many qualities like size and prey. One category specializes in hunting and killing very large prey by stunning the animals and swallowing them whole. Coffin rays and electric rays are examples of this type. Another category feeds on small prey or bottom feeds. Animals in this group include numbfishes & sleeper rays. In both categories, all use electricity as a means of defense. Appearance: One of the most distinguishing features of the electric ray is the pair of elongated fins that run the length of the fish’s body, forming the well known rounded wing look. The fins round near the fish’s rear, which is made up of a long, whip-like appendage, which houses the poisonous barb or stinger. The fishes are generally flat with protruding eyes that attach directly to the skin around the eyes, and because of this are not able to blink. They come in a variety of colors. The Pacific electric ray is the only species of ray that is native to the Pacific coast. It is one of the more aggressive species of electric rays and reports of divers receiving shocks from them are not uncommon. This is an extremely large ray that can deliver a huge shock, and for this reason has few predators. Females are larger than males and have been charted at nearly 140 cm and over 40 kg. They feed mainly on bony fishes such as mackerel or herring, but also consume others. Hunting with Electricity: The attack of the Pacific electric ray is one that a witness will remember. The electric animal hangs suspended in water, waiting for a prey fish to come within range. When an unsuspecting fish comes into range, the ray lunges forward in a quick motion and wraps the prey in the folds of its pectoral fins. It will kick with its tail and roll repeatedly in order to tighten its grip, all the while delivering electric shocks to its victim. Another common tactic involves burying itself in the sand during the daylight hours and rearing out to snatch passing fish. The maximum voltage during the initial attack is 45 volts. A ray will issue over 400 rapid pulses of direct current (about 5ms long each) during a violent attack, some delivering as many as 300 pulses in a single second. The size of the ray does not seem to affect the speed of the attack, but the temperature of the water will alter the speed of the pulses issued by the ray. The warmer the water, the faster the attack will be. Outside of hunting, rays are thought to use a special organ called an “ampullae of Lorenzini” to pick up electrical cues from possible prey fish when visibility is low. This explains their occasional habit of attacking artificially generated electrical shields. Interacting with People: There are no confirmed human fatalities from interactions with electric rays, but a shock from one is more than enough to knock down a full grown human. The ray has an electric organ on either side of its head or at the base of the pectoral fins to serve as a battery. The capabilities of these natural batteries have been known to man for millennia. There are even reports of ancient Greeks and Romans taking live rays from the sea and using weaker electrical charges to numb the pains of childbirth and various simple surgeries. Romans were also known to use the torpedo fish’s electrical currents in the treatment of headaches. .

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