The sensory capabilities of sharks, and other “elasmobranch” species like rays and skates, are truly remarkable. Illustration: Kate Hazell

What it's like to be a shark

Sharks and their cousins can detect electrical signals. Humans are just about catching up
May 6, 2021

There is something in the water. You, a shark, can smell it—at concentrations as low as one part per billion. In a swimming pool-worth of water, you can sniff out a single droplet of blood, or indeed fish oil, pheromones and all sorts of other things.

The sensory capabilities of sharks, and other “elasmobranch” species like rays and skates, are truly remarkable. Two-thirds of their brains are dedicated to those finely tuned olfactory skills, which make them the bloodhounds of the sea. But perhaps the most intriguing quality sharks have is their extra sense, electroreception.

They and their cousins can detect electrical signals—very tiny signals produced by every living thing, animal or vegetable. A fish hiding in the silt of the seabed might be invisible to the naked eye, but as it breathes it will expose the mucous membranes within its gills to the water, creating a tiny voltage that switches on and off like an alternating current.

That voltage puts them in danger. A nearby shark or a stingray can detect these small flickers of electricity through what look like skin pores on their muzzles: under the skin, these pores widen into tubes filled with conductive jelly and electrical receptors called “ampullae of Lorenzini.”

Stefano Lorenzini, a 17th-century Italian physician, first stumbled on these strange organs during a dissection, more than 300 years before their function was identified. But—returning to my quest to get inside animal consciousness—although we now have some understanding of how electroreception works, we still don’t know how it feels.

Or, most of us don’t. A small but not insignificant number of people—who fall into a wider group usually called biohackers—have opted to induce a similar “sixth sense” by having tiny neodymium magnets implanted into their fingertips. When they come into close contact with other magnets, the wearer feels strange twinges that they soon learn to interpret.

One electrical engineer with these implants said that after two years they quivered in the presence of electromagnetic fields, with a tingling sensation akin to “bumping your elbow and your fingers going numb.” Another user can sense the spinning of a hard drive, or a laptop charging. It feels, he said, like “an electric shock without the pain,” accompanied by faint vibration. If a shark can detect a small fish at a range of around three feet, he “can feel my microwave from 22 inches away.” Though he admits: “I don’t know if that’s ‘useful.’”

The sensations do not exactly take the self-experimenters into the mind of a shark—rather than creating a new sensory organ, the magnets stimulate pre-existing somatoreception (touch) sensors—but these reports can still offer some insight into what it might be like to move through the world with an awareness of its electrical properties.

In a 2017 paper, one Microsoft researcher imagined a near-future in which “wearable sensing and actuation technology” allows us all the ability to feel electromagnetic fields without slicing open our fingertips. “Being close to a resting person, we could sense heartbeats in distances of many centimetres,” he wrote. “We could feel people approaching from the back, which would contribute to a more sophisticated sense for situations that are not within our field of view. We would even be able to identify known people by their characteristic change in body electric potential while walking.”

This sounds to me like the birth of a whole new form of appreciating the world around us. Walt Whitman sang the body electric. Perhaps one day, like the shark, we all will.

Read all of Cal Flyn's "What it's like to be" series here