Fish Electric TECL#18119/ TECL #26890

Stock photo of an electric eel, Electrophorus electricus, a potentially dangerous freshwater fish.
Photo provided by Flickr
In order to characterize the degree of uniformity or `smoothness' of theelectric field around the fish, a quantitative measure was needed. To thisend, we used a measure of `energy' (proportional to electric energy) toquantify the degree of smoothness of the potential Φ along the EO as wellas along the interior and exterior skin boundaries. It is defined as:
Stock photo of an electric eel, Electrophorus electricus, a potentially dangerous freshwater fish.
Photo provided by Flickr
The vast number of electroreceptors enables the fish to determine not only the shape of an object, but its volume, size, material, and maybe even which direction it’s facing. The elephantnose fish can use the images formed through electrolocation to navigate its environment, avoiding hitting objects as it swims while hunting smaller prey. These images aren’t perfectly clear, but are like someone near-sighted seeing a blurry world when they don’t have their glasses on. This doesn’t affect the fish too much, as basic shapes and patterns are all that are needed to survive and thrive. How to Fillet a Fish with an electric knife
Photo provided by FlickrElectric Fish are a type of  found mostly in the waters of the .
Photo provided by FlickrElectric fishes use an  to probe the environment and create active electrodynamic imaging.
Photo provided by Flickr
A fish is considered to be an electric fish if it can electric fields. In this case it is said to be . If a fish has the ability to electric fields, it is said to be . Most fish that are electrogenic are also electroreceptive. Some electric fish live in the ocean and some live in freshwater rivers of South America and Africa. The figure below (from Moller 1995) provides a summary of the geographical distribution of electric fishes (click on the image to see a larger version). The figure also shows the location of the electric organ in each fish, and a sample of the waveform of the electric organ discharge.Strongly electric fish have an EOD that is powerful enough to stun their prey. Typical EOD amplitudes for these animals range from about 10 to 150 volts. Strongly electric fish are grouped at the top of the figure. Weakly electric fish generate an EOD that is typically less than one volt in amplitude. These discharges are too weak to stun prey, but are used for navigation, object detection (electrolocation) and communication with other electric fish (electrocommunication). Weakly electric fish are shown grouped together near the middle of the figure.Certain fishes like sharks, skates, rays and catfish can detect electric fields, and are thus electroreceptive, but they don't generate an electric field so they are not classified as electric fish. Most common bony fish (teleosts), including most fish that you would find in a tropical fish store or at the fish market, are neither electrogenic nor electroreceptive. (To study, not to eat!) We primarily study the South American weakly electric fish (black ghost knifefish) and (brown ghost knifefish). These fish have a wave-type EOD, with a high discharge frequency (about 1 kHz) and a weak electric field (a few mV near the fish). They are nocturnal hunters that feed on insect larvae and small crustaceans in freshwater rivers of South America.In different species of electric fish, the EOD waveform takes two general forms. In some species the waveform is continuous and almost sinusoidal (e.g., Apteronotus, Eigenmannia, Gymnarchus). These fish are said to have a wave-type EOD. In other species, the EOD waveform consists of brief pulses separated by longer gaps (e.g., Gnathonemus, Gymnotus, Raja). These fish are said to have a pulse-type EOD. The figure above illustrates the different types of EOD waveforms observed in different species.While electric eels use their electricity to stun prey and deter predators, the newfound fish use theirs to navigate in murky waters: They live under floating rafts of vegetation along the margins of the Amazon called “floating meadows.” (.)