What are the Ampullae of Lorenzini?

The ampullae of Lorenzini are special sensing organs found in cartilaginous fish (sharks, rays, and chimaeras). They are electroreceptors, forming a network of jelly-filled pores, and although they are mostly found in cartilaginous fish, they are also reported to be found in Chondrostei such as reedfish and sturgeon. Lungfish have also been reported to have them. Teleosts have re-evolved a different type of electroreceptors.They were first described by Stefano Lorenzini in 1678.

These sensory organs help fish to sense electric fields in the water. Each ampulla consists of a jelly-filled canal opening to the surface through a pore in the skin and ending blindly in a cluster of small pockets full of special jelly. The ampullae pores are plainly visible as dark spots in the skin. They provide fish with an additional sense capable of detecting electric and magnetic fields as well as temperature gradients.