How Can a Shark Find an Animal Hidden Beneath the Sand?

A shark searching the seafloor does not need to see its prey. It can detect the weak electric fields produced by the hidden animal’s body.

Muscle contractions, heartbeats, and activity in nerves move charged particles through living tissue. In seawater, this creates tiny electrical signals. Sharks and rays sense them using organs called the ampullae of Lorenzini.

On a shark’s head, the organs appear as small pores, especially around the snout. Each pore opens into a canal filled with conductive jelly. At the inner end are sensory cells capable of responding to minute differences in electrical potential. Together, the canals allow the shark to determine the direction from which a signal originates.

This sense becomes particularly useful at close range. A fish may bury itself beneath sand and remain motionless, defeating sight and making little sound. Its breathing and heartbeat still produce an electrical presence. A shark can follow that signal and strike at prey it cannot see.

Electroreception may also contribute to navigation. As a shark moves through Earth’s magnetic field, electrical effects are produced in its body and the surrounding seawater. Experiments indicate that some sharks use magnetic information, although scientists continue investigating exactly how the sensory systems cooperate.

The small dark dots around a shark’s nose are therefore not ordinary pores. They are openings to a sense humans do not possess, revealing a hidden electrical landscape in which every living animal is quietly announcing itself.