Electro-perception in Sharks and Rays

SHARKS and rays are extremely sensitive to alternating electric fields. A potential gradient of only 0.1 µV/cm is sufficient to evoke in Scyliorhinus canicula a reflex contraction of the eyelids (“winking of the eyes”), and to affect the respiratory rhythm of Raia clavata (“spiraculum reflex”)1,2. Such a weak electric field is perceived with the ampullae of Lorenzini. The ampullae are not only very sensitive to thermal and mechanical influences as found electrophysiologically3–5, but also respond to electrical stimuli6–8. Partial denervation of the ampullary system makes the head of Scyliorhinus canicula insensitive to weak electrical stimuli in the area where the eliminated ampullae open9. In the past few years, our investigations have been focused on the biological significance of the electro-perception in sharks and rays.