Deep

by James Nestor

  “What they’re listening for is random bursts of low frequencies,” he explains. “There’s a lot of that in AC/DC.” To that end, a little later, Schnöller and Fix will try their own test by blasting the water with tunes recorded by Rammstein, a hard-core metal band from Germany. “The longhaired shark will like it,” Schnöller quips.

  With the water bloody and thumping with kingfish screams, Buyle fixes an acoustic tag to his spear gun and prepares himself to go deep.

  “Come on, James, the water’s fine,” he calls to me from below. It’s 9:00 a.m. and already scorching hot on the boat. A quick dip sounds great. I’ve been on Réunion for five days now and haven’t touched the ocean. I slip into my swim trunks and try not to splash as I get in.

  Through my goggles, I watch Gazzo in the distance, descending slowly amid plumes of fish blood into the darker depths, spear gun in hand. Buyle follows, paddling quickly. When he reaches neutral buoyancy, he puts his arms at his side and glides effortlessly down. No matter how many times I see this, it’s always an awe-inspiring and spooky thing to watch.

  Beside me on the surface, Winram is flailing his arms and legs in the water as though he can’t swim, keeping a watchful eye through his mask on the seafloor below. It takes me a minute to realize that he’s trying to attract sharks by swimming slowly in a circle, flapping his arms and legs, and acting like a wounded seal. I realize that I’ve been doing exactly the same thing for the last few minutes. I suddenly feel like I’m standing at an ATM in a bad part of town. I very quietly scramble to the motorboat, pull myself onto the deck, and take a seat in the shade of the canopy, back where I belong.

  “Oui. Shark!” Buyle says a few minutes later as he surfaces. He calls out to Gazzo and Winram, telling them to dive down in hot pursuit. Fix turns up the volume on the car stereo. Schnöller and I peer over the side of the boat but can’t see anything. The divers are too far away. A minute passes. The ocean’s surface remains still and flat. Finally, Buyle bursts up, takes a breath, and then kicks back down. I haven’t seen Gazzo or Winram for a while, perhaps two minutes. I ask Schnöller what’s going on, but he just shrugs and shakes his head.

  Eventually all the divers return. Buyle pulls his spear out of the water; the acoustic tag is still stuck to the end of it. Back on the boat, Buyle explains that the sharks were disturbed by all the commotion and left. He, Gazzo, and Winram spend four more hours diving without seeing another shark. At around three in the afternoon, Schnöller starts the motor and we beeline back to the marina.

  “They are just so nervous,” says Buyle, yelling over the engine as we thump across open ocean toward the port. “It’s very unusual,” he says. “In Fiji, Mexico, the Philippines, you dive and there are sharks everywhere. You can’t help but be around them. But these sharks are different.” He exhales. “This could be a challenge.”

  THE FOLLOWING DAY, AFTER YET another failed mission—sharks spotted, none tagged—I’m knocking at the front door of Buyle’s rented apartment, a shabby concrete-block building a half a mile from Boucan Canot. He answers in a T-shirt, bare feet, and shorts, and leads me to a small desk cluttered with cameras, cords, and computers. His laptop screen shows a gallery of photographs of him swimming with hammerheads, whitetips, and other shark species.

  “Drop me in the water with some sharks, and I’m happy,” he says with a laugh. Buyle starts a video on his laptop. It shows a freediver floating through the gray haze of deep water, slowly approaching a shark the size of a station wagon. The diver, of course, is Buyle, and the shark is a fifteen-foot, four-thousand-pound great white. The video turns my stomach. I tell Buyle it seems like he’s asking for trouble.

  “Do I look like some adrenaline junkie?” he says, sipping water from a steel bottle, wearing his most monk-like expression. “Skydiving, jumping with bikes. I hate all that shit!” he says. “Freediving with sharks is the opposite of an adrenaline sport. You need to be calm, balanced. You need to know yourself. Being relaxed and in control is the only way you can do it.”

  Buyle grew up in a small house his father built, just paces from the forty miles of sand and wind-ripped grass that make up Belgium’s tiny coastline. His great-grandfather was the official photographer for the king of Belgium in the 1920s. His father was a successful fashion and advertising photographer until, at around age forty-five, he dropped out of the business and toured Europe in a Volkswagen, then married a woman half his age (Buyle’s mother) and turned to building sailboats in the garden at the back of the house. Buyle spent his youth playing in those boats and sailing with his father in the gray waters of the North Sea. The family traveled often, usually to exotic tropical locations. Buyle was snorkeling by age seven, spearfishing by ten, and swimming with sharks at thirteen.

  “I saw no signs of aggression,” he recalls. “I was happy to dive with them.” When he was fourteen, he and his friends started freediving. He admits that he knew nothing about it and had no idea how to train. “We had to just find out everything ourselves,” he says. “It was an adventure.”

  In 1988, the freediving film The Big Blue, a fictionalized account of the rivalry between freedivers Jacques Mayol and Enzo Maiorca, was released, and freediving’s popularity in Europe soared. Buyle, who was sixteen at the time, saw the film as a confirmation. “To me, the film just looked like a documentary of what we were already doing!” he says.

  It took Buyle four years of practice to dive down to one hundred feet, a significant depth at the time. After that, he says, everything opened up. By his early twenties, he was diving competitively, and by twenty-eight, he had claimed four world records in the sport, at one point doing a weight-aided dive to 338 feet.

  In 2003, during a training session for a world-record weighted dive to more than five hundred feet, Buyle suffered a horrendous accident. He made it down just fine, but as he was about to begin his ascent, the balloon designed to lift him back up didn’t inflate properly. He blacked out at two hundred feet. The balloon eventually dragged his comatose body to the surface. He suffered extreme trauma to his lungs but fully recovered after a month and continued doing deep dives.

  “To me, freediving was always about exploring the ocean, being a part of it,” he says. “It was a way to get to another level, go deeper into the water, push new boundaries.” Increasingly frustrated with the competitive, egocentric drive of his fellow freedivers, Buyle quit doing that kind of diving in 2004. “The exploration component was gone,” he says. “Freediving became just another sport.”

  Buyle now spends about two hundred and fifty days a year diving in oceans around the world, filming documentaries, photographing marine animals, lecturing at events, leading freediving tours, and, the thing he loves best, educating the public about sharks. “The fact is, for so long nobody knew anything about sharks,” he says. “And humans fear what they don’t know.” Tagging, Buyle says, can help us allay what he calls our irrational fear of this animal.

  His first job tagging was on the island of Malpelo, off the west coast of Colombia, in 2005. Colombian researchers had speculated that hammerhead sharks in the area were migrating as far south as the Galápagos Islands, some fourteen hundred miles away. If they were, Colombia could establish the whole region as a marine reserve and protect the shark, but first the scientists needed to prove it. They called in Buyle. During three trips spanning three years, he dove to depths of more than two hundred feet and tagged a hundred and fifty hammerheads with both acoustic and satellite tags. From the data, researchers found that hammerheads were not only migrating to waters around the Galápagos and farther away but doing so in perfectly organized packs, several hundred strong, in very deep water. The data on ferox sharks, an extremely rare species believed to exist in only three or four places on the planet, showed that they were diving a staggering six thousand feet down and migrating hundreds of miles and back again. Nobody had any idea that sharks could do this kind of thing, because nobody had bothered to look. “We were the first,” says Buyle, shooting me a smile. As
a result of these and other conservation efforts, in 2006, 3,300 square miles around Malpelo were designated as a UNESCO World Heritage site.

  WHILE NOBODY KNOWS EXACTLY HOW hammerheads, feroxes, and other sharks can navigate in permanently black, deep waters, most marine researchers believe that tiny bumps on the sharks’ heads and the sixth sense of magnetoreception have something to do with it. Called ampullae of Lorenzini, after the Italian anatomist who described them in 1678, these little bumps, which look like tiny freckles along the shark’s nose, are actually pores filled with electrically conductive jelly. At the bottom of each of the roughly fifteen hundred pores is a hair cell that resembles one of the tiny hairs inside a human ear. These cells, called cilia, can pick up the slightest change in electrical fields in the water. They work in coordination with the lateral line, a series of sensory cells that run down the middle of the shark’s back from nose to tail.

  All animals, including humans, generate weak electrical fields from neurons constantly firing off electrical signals. A shark’s body works like an enormous antenna, tuning in to the signals pulsing around it. When the shark picks up a signal it likes, it moves in closer. If the signal seems like something it could eat, it takes a bite.

  Buyle tells me that the full wetsuit he and the other freedivers are wearing isn’t just meant to keep them warm—the water temperature in Réunion is a balmy 78 degrees—but also to dampen the electrical signals their bodies send out.*

  Sharks’ electroreceptive senses are remarkably acute. Tests on captive great white sharks have shown that they can sense electrical fields as small as 125 millionths of a volt. Smooth dogfish sharks can detect 2 billionths of a volt, while newborn bonnethead sharks can detect fields less than 1 billionth of a volt.

  To put this in perspective, imagine dropping a 1.5-volt battery in the Hudson River in Manhattan and then running a wire from that battery to Portland, Maine, some three hundred and fifty miles away. The dogfish and bonnethead sharks could detect the faint electrical field coming off the wire. This sense is five million times stronger than anything humans can feel. It’s by far the most acute sense yet discovered on the planet.

  (If these facts are supposed to allay people’s fears about swimming with sharks, Buyle and his team may have to work harder on their messaging. Knowing that sharks can track the weakest electrical signals pulsing from my head and heart only makes me fear them more.)

  Because sharks’ electroreceptive sense is so keen, many scientists believe they can sense the subtle energy of the Earth’s electromagnetic field, which puts out a force of about one-quarter to one-half of 1 percent of the force of a standard refrigerator magnet—significantly stronger than the electrical fields sharks already sense in their prey.

  Sharks aren’t the only creatures with magnetoreceptor bumps on their noses, and they aren’t the only underwater animals tuned in to magnetic fields.

  In 2012, a group of German researchers were trying to figure out how trout could return to the same spawning ground every year. They suspected their ability to navigate blind underwater had something to do with the black bumps on their trout noses, which closely resemble the sharks’ ampullae of Lorenzini. The researchers scraped off a few bumps and exposed them to a rotating electric field. The cells started spinning in sync with the field. In other words, trout had cells on their noses that worked the same way as a compass needle, and they were probably using these cells for navigation.

  But perhaps the bigger discovery was that the bumps contained magnetite, a highly magnetic mineral that was used in early compasses.

  Sharks, dolphins, some whales, and several other ocean migrators also have deposits of magnetite in their noses or elsewhere on their heads and are probably using them in the same way.

  During full moons, some mollusks use magnetic north as a guide to move from deeper to shallower areas while they hunt. Even marine bacteria, which paleontologists believe date back over two billion years and may represent some of the Earth’s earliest inhabitants, use tiny bits of magnetite to swim along magnetic field lines. This natural magnetic GPS has been around for billions of years, and, like all life, it began in the ocean.

  Humans also have magnetite deposits. They’re found in the skull, specifically in the ethmoid bone, which separates the nasal cavity from the brain. The location of these deposits in a human head corresponds closely to their position in sharks and other migratory animals—a relic from the magnetosensitive fish from which humans and sharks both evolved five hundred million years ago.

  WHETHER OR NOT MODERN HUMANS can use the magnetite deposits or some other receptors to attune to the Earth’s subtle magnetic field is still not known. But three decades of scientific trials suggest it’s possible.

  The first researcher to attempt to document and measure human magnetoreception was Robin Baker, a lecturer at the University of Manchester. Baker had long wondered how ancient Polynesian sailors could navigate hundreds of miles across open ocean and consistently find their way back home. Celestial or solar navigation could work some of the time, but not always—clouds covered the sky for days, and rough seas could quickly throw a boat off course.

  Captain James Cook wrote about Tupaia, a high chief from Raiatea, near Tahiti, whom he took aboard his ship the Endeavour in 1769. Tupaia drew a detailed and accurate map that spanned more than twenty-five hundred miles, from the Marquesas to Fiji, and included 130 islands. For the next twenty months, the Endeavour sailed the South Pacific and beyond, and Tupaia could always point in the exact direction of his island home, regardless of the Endeavour’s location, the time of day, or the conditions at sea.

  The Guugu Yimithirr, an Australian Aboriginal tribe, had a remarkable sense of direction that they incorporated into their language. Instead of using words meaning “right,” “left,” “front,” and “back,” Guugu Yimithirr used the cardinal directions of north, south, east, and west. If a Guugu Yimithirr tribesman wanted you to make room for him on a bed, he’d ask you to move a few feet west. Guugu Yimithirr didn’t bend backward, they bent northward, or southward, or eastward.

  The only way Guugu Yimithirr could communicate was by knowing their exact coordinates at all times, which was a hard thing to do at night or in an enclosed room. But it was second nature for them, as well as for a host of cultures throughout Indonesia, Mexico, Polynesia, and elsewhere, whose languages were also based on cardinal directions.

  In the 1990s, researchers from the Comparative Cognitive Anthropology research group at the Max Planck Institute for Psycholinguistics in the Netherlands placed a speaker of Tzeltal—a Mayan directional language spoken by about 370,000 people in southern Mexico—in a dark house and spun him around blindfolded. They then asked the Tzeltal speaker (who was unnamed in the study) to point north, south, east, and then west. He did this successfully, and without hesitation, twenty times in a row.

  The remarkable navigational abilities of these ancient cultures weren’t exceptions; they were the norm. In a world without GPS and maps, knowing your exact location in a trackless desert, forest, or ocean was a matter of survival. All the people in these cultures developed an innate sense of direction that did not rely on visual cues. Robin Baker believed this sense was magnetic. In 1976, he decided to test it.

  In Baker’s first experiments, he blindfolded groups of students, drove them from the university along a winding route several miles out of town, and then led them, still blindfolded, one by one to an open field. He asked them to point in the direction of the university. The students frequently pointed in the right way, succeeding more often than pure chance would predict. He ran tests in different locations, at different times, with different students. In one test, the thirty-nine students pointed in the right direction with 80 percent accuracy, the same as closing your eyes, spinning around, and pointing to between 10:30 and 12:00 on a clock dial. Later tests had the same results. Baker repeated his experiment 940 times over the next two years with a total of 140 students. Overall, the experiments strongly sug
gested that the students were using some sort of nonvisual sense to orient themselves to their surroundings.

  Baker then tested to see if the human navigational sense was magnetic. Earlier experiments with green turtles and birds had shown that tying magnets to the animals’ heads would destroy their ability to navigate even very short distances. (The magnetic field from the head magnet was stronger than the Earth’s magnetic field, and the theory was that it confused the animals into thinking that every direction they turned was north.)

  Baker tied magnets to the heads of half the students, nonmagnetic brass bars to the heads of the other half, blindfolded them, drove a circuitous route out of town, and released each into an open field. The students without magnets were able to point in the right direction significantly more accurately than those with magnets. Additional tests yielded similar results. The magnets, Baker argued, were disrupting the students’ ability to navigate, just as they did with birds and turtles.

  After crunching the numbers from all his experiments, Baker wrote, “We have no alternative but to take seriously the possibility that Man has a magnetic sense of direction.” The results were published in the prestigious journal Science.

  Baker said that human magnetoreception was distinct from other senses, like vision and smell. Those senses are conscious, meaning that we are aware of them and immediately perceive it when they turn on (like when you open your eyes) and turn off (when you plug your ears).

  Human magnetoreception works differently. It is an unconscious, latent sense; we can’t feel it turning on or off in the same way that, most of the time, we don’t notice that we’re breathing. In this, magnetoreception is like the Master Switch; we don’t know it exists unless we put ourselves in a situation in which we have to use it.