Sharks can sense their prey through electroreception.
Tiny electrical signals are received from their environment via a series of pores peppered over the head, which are distributed in discrete patterns that vary from species to species.

In the White Shark, there is a pair of elongate clusters on top of the head above the eyes, another pair of V-shaped clusters surrounding the nostrils underneath the snout, a sausage-shaped cluster under each eye, and an oval cluster extending along each side of the chin.
These pores open to tiny bottle-shaped cells that are filled with an electrically conductive jelly. These cells are termed ampullae of Lorenzini, after the Italian anatomist who first described them in 1678. The ampullae are based on hair cells as the key functional unit, which has been adapted to sensing sound, vibration, and electrical stimulation.

Seawater is an ion-rich medium that conducts electrical fields moderately well. Seawater moving over the magnetic field lines of our planet provide a weak but richly textured electrical ‘map’ of the immediate environment. A shark’s body contains a rich broth of electrically charged biomolecules called electrolytes, which allow cells to communicate with each other. As it swims across geomagnetic field lines, electrical currents are induced in its body that provide navigational cues.

Scalloped Hammerheads in the Sea of Cortez use this built-in compass sense to follow ‘magnetic highways’ along the seafloor between separate nocturnal feeding and diurnal socializing sites.
On a much smaller scale, cellular activity generates tiny electric fields that can reveal the presence of potential prey that would otherwise be hidden from sharks. A particularly vivid example is provided by the Great Hammerhead, which detects buried stingrays by sweeping its wide, ampullae-studded head over the bottom like the sensor plate of a metal detector.
Studies about the Great White Shark are extremely difficult to conduct since they are not able to be kept in captivity for longer than a couple of days, but it has been revealed that they do have extreme electromagnetic sensitivity which they use to track down prey from miles away.

Some shark species have been revealed to be able to detect electric fields less than 1 nanovolt per square centimetre. This is equivalent to the electric field of a flashlight battery connected to electrodes some 16,000 kilometres apart in the ocean. Such incredible electrical sensitivity is over five million times greater than anything you or I could feel and is by far the most acute in the Animal Kingdom.

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