How Animals Produce Electricity

      There is an organ which situated in the tail section of a fish called the ‘electric organ’. In this organ, there are cells that are called ‘electrocytes’. These cells receive signals from the brain and produce electricity. In strongly electric fishes, the electric organ contains huge amount of electrocytes. This allows them to discharge high voltage electricity, sometimes as high as 600 volts. For weaker electric fish, they simply have a smaller electric organ, therefore producing a lower voltage of electricity. These fishes use electricity to paralyze or electrocute their prey, for self protection, for communication and for navigation. Click here for an animation showing how a fish uses electricity to navigate.

      There are two types of discharges, the pulse type and the wave type. All strong electric fishes are of the pulse type which means they discharge short but powerful electrical pules at irregular intervals. For most weak electric fishes, the EODs (electric organ discharge) are very constant and continuous. However, when two fish with similar frequencies meet, confusion occurs which causes problems in electrolocation. To solve this problem, they will alter frequencies until they are able to recognize only their own frequencies.

      Not only can these fishes produce electricity, they can also sense electricity from other creatures. They have a very sensitive organ called an ‘electroreceptor’ which is embedded in their skin. This organ picks up the slightest change of electric field caused by nearby objects. This allows the fish to feel the surrounding environment. This process is called ‘electrolocation’.

      Not all types of fish can produce electricity. Some fish can only sense electricity. Some examples of these types of fishes are, sharks, rays, skates, catfish, and paddle fish. These fishes sense weak electrical fields from their prey and accurately locate the prey. This type of electrolocation is known as ‘passive electrolocation'.

Further Knowledge

      The organ is located in the posterior of the fish and the synchronous firing of the organ in controlled by the midline medullart nucleus, called the pacemaker nucleus, located in the brain. The multinucleated cells that make up the organ are either myogenically (muscle) or neuronally (nerve) derived. The cells that make up the organ are called electrocytes. The columns of the electrocytes are innervated by supramoterneurons which carry the signal from the brain stimulating the EOD by depolarizing the electrocytes. In hummers the electrocyte is never fully depolarized because the stimulation is constant, which results in the sinusoidal wave.