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Man’s fascination with electricity began long before Benjamin Franklin flew his fabled kite in the lightning storm. For hundreds of years, people have admired and coveted this natural power, seeking to create it, harness it, or control it. While modern technology would lead us to believe that we have mastered these lofty goals, the disheartening fact remains that Mother Nature has beaten us to it. Within the animal kingdom, there are literally hundreds and hundreds of electric animals, common and obscure, which are just simply shocking!
Probably the most common animal with electric capabilities is the stingray. There are fourteen known species of stingray that range in habitat from the Pacific coasts of California to British Columbia all the way to various Atlantic locations. Other fish belonging to the order include the coffin rays, sleeper rays, and numbfishes, all with electric capabilities. The order totals over sixty creatures.
Classification: Stingrays are primarily divided into two categories, based on numerous qualities including their size and type of prey. The superfamily, Torpedinoidea, specialize in hunting and killing very large prey by stunning the animals and swallowing them whole. Coffin rays and electric rays belong to this superfamily. The second superfamily, Narcinoidea, consists mainly rays that feed on small prey or bottom feed. Animals in this superfamily include numbfishes and sleeper rays. The only universal commonality between the superfamilies is the use of electricity as a means of defense.
Appearance: The classic electric ray is probably the animal that most comes to mind when people think of electric fish. 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. The stingray cannot blink for this reason. They are streamlined and their family name inspired the torpedo underwater military device. 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 formidable 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 cephalopods and invertebrates.
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. (Other, lesser known species of ray have been known to produce a more significant charge). 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. The power of some rays has been measured as a full kilowatt. 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 and more commonly, gout. The Roman physicist, Scribonius Largus, detailed such procedures in his Compositiones medicae (c. 50 A.D.).
Another very well-known electric fish is the eel, which is a freshwater fish found primarily in the waters of South America. It can be found in rivers, lakes and streams, and often muddy swamps and backwaters. It will not venture to the sea because the salt effectively causes a short circuit during electrical attacks.
The electric eel received its common name because
of its elongated, snake-like
but it is not a true eel. Rather, it is a member of the
Gymnotiformes, or knifefishes. They are more
closely related to carp and catfish than they are true eels. It is such an
interesting species of fish that
it has been classified and reclassified numerous times, with the taxonmy
continuing to evolve as science progresses.
Appearance: The electric eel has a very elongated and tube-like body, absent of pelvic or dorsal fins to make them appear more serpentine. They possess a shallow but extended anal fin that stretches the entire length of the body to the tip of the tail and waves like an ominous, trailing ribbon as the fish swims. Their bodies are generally grayish brown on the upper side and yellowish on the underbelly, with mature males sometimes becoming a darker orange underneath. It has no scales, but instead features a thick slimy skin, which protects them from harm, including its own electrical current.
Electric eels can become quite large, some growing to lengths of over eight feet. They are very muscular and can weigh nearly fifty pounds when mature. They are the largest of all the Gymnotiformes. They are the elite predator in their habitat and have no natural enemies.
Using Electricity: The electric eel is a very effective predator, despite its poor vision. It has an excellent sense of hearing, however, and also a Sachs organ, which has been linked to electrolocation. This organ, which is the third and smallest of the eels electric organs, emits a low voltage charge of about 10 V. It is thought that the eel uses these weak charges for orientation, as well as locating prey and potential mates. Some scientists feel it is also used in a rudimentary form of communication.
The more powerful electrical charges come from the Hunters Organ and the Main Organ. All of the organs together are comprised of some five to six thousand electroplaques that are stacked in a manner similar to the common battery. When the eel becomes upset or is preparing to attack a prey animal, its brain signals the electric cells in these organs. An ion channel is opened and positively charged sodium flows into the organs, reversing the charge for a moment. The product of this sudden shift or disturbance in voltage creates an electric current. Eels can produce a shock typically as powerful as 650 V but have been known to emit bursts over 700 V. These are the shocks issued during predation and defense. In total, the three electric organs make up 80% of the electric animal's body, with the vital organs comprising the other 20%.
Eels prey upon a range of smaller creatures. Eels
have no maxilla teeth, but have the luxury of taking their time while consuming
a stunned animal. They prey upon mammals and fish, sometimes also taking an
inveterbrate if an easy opportunity presents itself. The younglings will eat
invertebrates, primarily crabs and freshwater shrimp. Newly hatched eels will
also consume the eggs and embryos from later batches. Eggs are laid in a nest
made of the male’s saliva. As many as 17,000 eggs are laid in a single clutch.
Eels and People: Deaths to people from electric eel shocks are very rare, but not unheard of. Repeated shocks have been known to cause respiratory and heart failure. People drowning after being stunned is more common. Still, the eel is a coveted pet in some areas. They are difficult to catch because of their potent defensive strikes. However, releasing repeated charges will wear out an eel, making them vulnerable to capture. In captivity, an eel must be kept in a tank no smaller than 100 gallons and should be the sole inhabitant of its artificial environment. Adult eels will generally tolerate one another, but young eels will fight for supremacy and eels of any age will attack other fish. Occasionally, eels are also used as a food source. Their ability to emit a powerful charge up to eight hours following death deters this habit in most places, however.
A popular type of fish in modern aquariums is the
electric catfish, mainly due to their dynamic natures. It is originally native
to Africa with the densest populations in the Western and tropical regions,
including the Nile River. It is an aggressive and carnivorous creature that will
attack and consume almost any prey up to half of its own size. It lurks in rocky
areas in dark freshwater, waiting for prey to happen by. It seems to prefer
night hunting and is fairly still during the day.
Appearance: Despite its similarities to other catfish, the electric catfish is the only species in a own. The electric catfish does not look very different from more common freshwater catfish found in rivers and lakes throughout the world. The catfish does not have dorsal fins or fin spines, and has a thick skin instead of scales. Perhaps the most telltale feature of the catfish, as with all catfish, is the series of barbels or (commonly referred to as “whiskers” lending to the fish’s name) found around its mouth. The electric catfish has three sets of barbels with the nasal pair being absent in this species. Contrary to common myth, the whiskers are not the source of the catfish’s electric shock ability.
The electric catfish is a large breed of catfish and has a wide range of sizes. Some are small enough to be kept comfortably in large aquariums. Others, in the wild, grow to be upwards of thee feet long and weigh more than fifty pounds. They have no striking colorations, and are often referred to as “sausages with whiskers.”
Using Electricity: Catfish use
electricity in a variety of ways. Like the electric eels, catfish are able to
send weak electric charges into the water to serve as a type of radar, helping
the fish to navigate in its murky environment. The fish emits a continuous
electric current as it swims or rests. Special receptors beneath its skin allow
it to detect any disruptions in the current, making it an effective navigational
tool. It can also be used for finding prey. In truth, many species of catfish
have similar abilities. The electric catfish is also sensitive to magnetic
fields, although how the fish detects magnetism remains a scientific mystery.
The electric catfish, however, also uses its more powerful current to stun prey and to defend itself when it is attacked by predators. The electric catfish can generate a powerful charge up to 350 volts. The electric animal feeds mainly on other fish, but will also take invertebrates, such as freshwater shrimp, as a meal. The strength of the shock is directly related to the size of the animal, with larger fish emitting more powerful shocks. Charges can last up to thirty seconds. These can prove deadly to other fish, but have no effect on the catfish itself.
Electric catfish are vicious defenders of their territory and will attack other catfish upon sight. Often the battle begins with open mouth displays and thrashing. It escalates to barbel wrestling and flank biting. Ironically, the fish seldom discharge when fighting their own species.
Electric Catfish and People: It is not at all uncommon to find electric catfish for sale to the public, although no successful captive breeding program has been founded. Feeding in captivity is altered to match the size of the fish and lifestyle of the owner. Most commonly, captive catfish are given shrimp, earthworms and smaller live fish. Even a tiny two-inch catfish can deliver a potent charge, making their handling very tricky. The electric catfish has co-existed with man for countless centuries. There are pictures of electric catfish on Egyptian tombs dating back over 5000 years. The ancient Egyptians harbored a healthy respect for the electric catfish because of its shocking capabilities. Its name translates to mean “he who has saved many in the seas.” Presumably, this was due to the loss of many nets of fish when they were dropped back into the water following a discharge from a netted catfish.
Other Electric Animals
While stingrays, eels and catfish are the most widely known animals with electrical capabilities, there are many, many more. Over 500 different creatures harbor the ability to create an electrical shock. Elephant fishes, bonytongues, and stargazers are all fish with various degrees of electrical power. Many fish use electric fields as a navigational tool, similar to the electric catfish. Most electric users are aquatic.
One legendary beast, however, is decidedly not aquatic. The Mongolian Death Worm is said to be a large worm in the Gobi dessert that possesses either acid or electricity as a means of attack. While there is no concrete evidence that the Death Worm exists, it is almost universally accepted and described by natives of the desert. It is another great mystery of electrical animals.