ampulla of Lorenzini

ampulla of Lorenzini, any of the specialized sensory organs found in certain types of fishes that enable them to detect weak electric fields in their environment. The ampullae occur specifically in cartilaginous fishes, such as sharks, rays, and skates, as well as in some bony fishes, such as coelacanths and sturgeons. Arranged in an extensive sensory network mainly on the head, the ampullae aid in prey detection, navigation, and orientation, particularly in murky waters or at close range where vision is limited. They represent one of the most refined examples of electroreception in the animal kingdom.

A fish may have multiple ampullae of Lorenzini, with thousands of tiny pores—the exact number, size, and distribution varying by species. The ampullary organs make up a network of gel-filled canals that open to the surface of the skin through the pores, which lead to clusters of electroreceptor cells located in bulb-shaped chambers beneath the skin. At the base of each chamber, nerve fibers emanate that combine to form a nerve bundle leading to the central nervous system. The electroreceptors in each chamber are highly sensitive to changes in voltage, allowing the fish to sense the bioelectric fields produced by other organisms, as well as variations in temperature and salinity.

Ampullae of Lorenzini were initially described in 1663, by Italian physician and biologist Marcello Malpighi. They were first described in detail in 1678, by Malpighi’s student the Italian physician Stefano Lorenzini, whose observations laid the foundation for the later discovery of electroreception as a distinct sensory system in aquatic animals.