Electroplax

Electroplax refers to the electroplax organ, a specialized electric organ found in certain fishes. It comprises many electroplaques—stacks of electrocytes, which are modified muscle cells that have lost contractile ability. The electroplax is derived from skeletal muscle tissue and arranged into arrays that can be activated by the fish’s nervous system to produce electricity. When stimulated, the electrocytes depolarize, and the voltages from many cells add in series to generate a macroscopic electric discharge. The design yields high voltage at relatively low current; higher currents are produced when multiple electroplates operate in parallel.

Electric discharges are used for defense, predation, and in some species for electrolocation in turbid water. Discharge characteristics—voltage, duration, and pulse pattern—vary by species and ecological niche. The electroplax organ is a feature of several groups of electric fishes, including gymnotiforms (South American electric eels) and torpediniforms (electric rays). The organ’s arrangement allows rapid, synchronized output, exploiting the properties of thousands of electrocytes arranged in series and parallel networks.

Evolutionarily, the electroplax organ has arisen from muscular tissue in multiple lineages, illustrating how muscle cells can be repurposed into specialized bioelectric generators. The study of electroplax and its cells (electrocytes) has contributed to understanding bioelectricity, neuromuscular control, and the cellular basis of voltage generation. In research contexts, electroplax tissue serves as a model for ion-channel dynamics and the principles underlying high-voltage biological outputs.