Electro-perception in Sharks and Rays

Abstract

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 electrophysiologically^3–5, but also respond to electrical stimuli^6–8. 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.