Imagine swimming in the ocean at night, the water around you completely dark with only the faint ambiance of the deep to keep you company. You can’t see more than a few feet in front of you, even with the moon’s light shining through the water column. For many marine organisms, this mysterious environment would spell out “DANGER!”. For Sharks however, this is where they thrive. Sharks have a secret weapon that allows them to hunt with incredible precision even when visibility is low, this is called electroreception. Using tiny, jelly filled pores on their snouts called the Ampullae of Lorenzini, sharks can detect the small electrical signals given off by the muscles and hearts of other animals. This incredible sixth sense means that even a fish buried under sand has nowhere to hide.

The Ampullae of Lorenzini allows sharks to detect electrical pulses as weak as five billionths of a volt per centimeter. This means that even in the lowest visibility conditions, like murky water, or complete darkness, they can still pinpoint their prey. If their prey is injured, it will likely send out a more irregular signal making it even easier to find. All these advantages make electroreception an almost perfect compliment to shark’s keen sense of smell and sharp vision. Some species, like hammerhead sharks, are especially adapted to use electroreception to hunt, with their wide, flattened heads distributing electroreceptors over a large area, essentially scanning the sea floor like a metal detector.

Above you can see the electroreceptors (tiny black dots) on the snout of the tiger shark

Electroreception does not only serve as a way to find food, but it may also function as an internal compass for sharks. Research suggests that sharks may use electroreception to sense the Earth’s magnetic field, helping in long distance migrations across the ocean. This has also inspired some practical applications, with scientists developing electric deterrents to reduce shark bycatch and protect swimmers without actually harming the sharks. Sharks are far from the mindless killers they are portrayed as in pop-culture. Instead they are one of Mother Nature’s most beautifully complex and effective predators on the planet.