A shark can locate prey buried in the sand without seeing or hearing it. The secret lies in tiny pores on its snout, and the way they work is hard to imagine.
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These pores lead to small pouches filled with a conductive gel, known as the ampullae of Lorenzini. At the base of each pouch, receptor cells respond to tiny changes in the electrical potential of the water, then send the information to the brain through nerve fibres.
Experiments by Kalmijn on sharks showed that a field of about 5 nanovolts per centimetre could be enough to trigger a simulated feeding attack. However, this threshold applies to the species tested and should not be extended to all sharks.
The organ puzzled researchers for a long time. First described in 1678 by Stefano Lorenzini in the torpedo ray, its function remained unclear for a long time.
