Sharks have a sixth sense that helps them locate prey in murky ocean waters. They rely on special pores on their heads and snouts, called ampullae of Lorenzini, that can sense electric fields generated when nearby prey move. The pores were first described in 1678, but scientists haven’t been sure how they work. Now, the answer is a bit closer.
The pores, which connect to electrosensing cells, are filled with a mysterious clear jelly. This jelly is a highly efficient proton conductor, researchers report May 13 in Science Advances. In the jelly, positively charged particles move and transmit current.
Marco Rolandi of the University of California, Santa Cruz and colleagues squeezed jelly from the pores of one kind of shark and two kinds of skate and tested how well protons could flow through the substance. Good proton conductors, including a protein found in squid skin, occur in nature. But the jelly is the best biological proton conductor discovered so far. In fact, even humankind’s best technology isn’t wildly better. The most efficient proton conductor devised by people — a polymer known as Nafion — is a mere 40 times better than the stuff sharks are born with.