one. We have about three more breaths until they go down,” Ari shouted.
We trailed the laggard of the group, maneuvering the boat into position. Ari lowered himself across the bow and held the pole against his torso, extending the tip with the tag just ahead of the dorsal fin as we motored close to the behemoths moving yards away. Then, in a decisive motion, Ari launched the tip of the pole toward the whale’s back, where the tag’s suction cups hit the skin with a satisfying thwack. The whale rolled beneath the surface as we pulled back to pause and wait for it to return. We spotted its sleek, shiny back as it arose again, marked with a neon tag, and we cheered. The whale took one last breath before it raised its monstrously wide tail flukes out of the water and slipped down into emerald darkness with the others. Ari radioed back to the Ortelius. “Taaaaag on,” he said with a hint of swagger as he grinned at me.
Tag on
The whole rodeo of tagging is a bit like sticking a smartphone on the back of a whale, complete with the logistics of getting close enough to a forty-ton mammal in the first place. Just as your smartphone can record movies, track where you go, and automatically rotate images, the same technology—miniaturized and cheap, combining video, GPS, and accelerometers all in one device—has fueled a revolution in understanding how animals move throughout their world. Scientists call this new way of recording organismal movement biologging, and it has captured the interest of ecologists, behavioral biologists, and anatomists, all interested in knowing the details of how animals move through space and over time. Biologging has been especially important for revealing the daily, monthly, and even annual meanderings of animals that are extremely difficult to study. Stick a tag on a penguin, a sea turtle, or a whale, and there’s a chance to know how it swims, what it eats, and everything else it does whenever you’re not around to watch it—which is most of the time, for animals at sea.
The logistics of studying whales places them in a realm truly apart from every other large mammal on land or at sea. To know anything about them in the wild takes time on a boat, sticking a tag on their back, sliding a camera underwater, or spying overhead with a drone—if you’re lucky enough to come upon them in the first place. Biologging is helping us overcome this challenge by giving us a remote view into their lives, an extension of our senses more intimate and sometimes more detailed than any telephoto lens. In the case of humpbacks, tag data have revealed how these gulp-feeding whales lunge at large schools of krill and other prey, oftentimes in coordinated attacks. It’s a form of pack hunting, which might seem strange for a species celebrated as gentle giants. But baleen whales are serious predators, not like grazing cows but more like wolves or lions, pursuing their quarry with strategy and efficacy. Don’t be fooled by their lack of teeth, or just because krill don’t bleat in terror.
Hours later the Ortelius prowled silently through Wilhelmina Bay, with a pair of massive spotlights leading the way in search of icebergs in our path. Outside on the bow, I watched heavy snowflakes drift through the cones of light as Ari unfolded the metal radio antenna that would lead us back to our tag. The tags we were using had to be re-collected to yield their data; we would have to find and physically pluck them out of the water, provided that they’d already been knocked off the whales’ backs. By design, they can last minutes, hours, or even days from the force of suction alone, before being scraped, being bumped, or falling off. Its buoyant neon housing would keep the whole device floating on the surface until we triangulated its position.
Over the course of his career, Ari has probably tagged more species of whales than anyone, in all circumstances and in every ocean. Beyond friendship, mutual colleagues, shared ambitions, and wry humor, we were working together in Antarctica to build a bridge between our disciplines—paleontology for me, ecology for him—because questions about how whales evolved to become masters of ocean ecosystems over fifty-odd million years need to be grounded in the facts of what whales do today. Bridging gaps between disciplines sometimes necessitates spending time side by side. All the better if it’s in the field.
The metal prongs that Ari assembled looked like an elaborate set of rabbit ears from an old television set. He plugged the antenna into a small receiver with a speaker, and after a few moments, we heard a series of intermittent beeps. “That gap between the beeps tells us that the whale is sleeping, rising up to the surface to breathe, and then sinking back down.” Ari smiled. “Just dozing, belly full of krill. Not a bad way to spend a Saturday night.” We would need to come back later and listen again for our tag until it floated freely, beeping uninterrupted.
Most large baleen whale species alive today belong to the rorqual family, which feed on krill and other small prey by lunging underwater. They comprise the more familiar members of the cetacean bestiary, including humpbacks, blue whales, fin whales, and minke whales. Rorquals are also the most massive species of vertebrates ever to have evolved on the planet—far heavier than the largest dinosaurs. Even the smallest rorquals, minke whales, can weigh ten tons as adults, about twice as much as an adult bull African elephant. Rorquals are easy to distinguish from any other baleen whale, such as a gray whale or a bowhead whale: look for the long, corrugated throat pouch that runs from their chin to their belly button. (And yes, whales have belly buttons, just like you and me.) The features that make rorquals so obviously different from other baleen whales also play a critical role in how they feed.
Across whole ocean basins, individual whales find their food using probability, heading for feeding grounds burned into memory from a lifetime of migration. Rorquals travel routes that span hemispheres over the seasons; an individual whale might migrate from the tropics in the winter in search of mates and to bear young, then to the poles during the summer to forage under constant sunlight. Baleen whales still retain olfactory lobes, unlike their toothed cousins, such as killer whales and dolphins, which have lost them. Baleen whales might smell some aspect of their prey at the water’s surface, and it is possible that this mechanism could refine their search once on the scene. Originally their sense of smell evolved for transmission through air, not water; we know little beyond the basics about this sense in whales. Somehow, whales manage to be in the right place at the right time to feed. And what’s clear from biologging is that once in the right place, baleen whales spot the prey patches from below, probably approaching them by sight. Lacking the echolocation of their toothed relatives, vision is likely the dominant sense for baleen whales at short range.
With prey in range, a rorqual accelerates, fluking at top speed, and begins the amazing process of a lunge. Surging from below, it opens its mouth only seconds before it arrives at a patch of krill or school of fish, which may be as big as or bigger than the entire whale. When it lowers its jaws, the rorqual exposes its mouth immediately to a rush of water that pushes its tongue backward, through the floor of its mouth, into its throat pouch. In mere seconds, the accordion-like grooves of its throat pop out like a parachute. After engulfing the prey-laden water, the whale slows, almost to a halt, pouch distended and looking bloated, nothing like its airfoil-shaped profile from moments prior. Over the next minute, it slowly expels water out of its mouth through a sieve of baleen, until its throat pouch returns to its original form, the prey swallowed. For their part, krill and fish deploy collective defensive behavior by dispersing to try to escape the oncoming maw of death. In the end, a successful whale takes a bite out of a much bigger, more diffuse and dynamic superorganism.
Lunge feeding has been described as one of the largest biomechanical events on the planet, and it’s not hard to imagine why when you consider that an adult blue whale engulfs a volume of water the size of a large living room in a matter of seconds. Tags on humpbacks in other parts of Antarctica show how they sometimes feed close to the seafloor in pairs, swimming alongside each other as they scrape the bottom with their protruding chins in mirrored unison. Tags have also shown us that rorquals are right- or left-handed, just like us, favoring either a dextral or sinistral direction when they roll their bodies to feed.
The more scientists tag whales, the more it’s apparent that there’s still
