A century after the publication of Moby Dick, scientists equipped with acoustical devices began listening to the “still stranger world”—Melville’s phrase—below the waves. That world was noisier than previously imagined, and among the noises heard and recorded were loud, rhythmic clicks that Elizabeth Kolbert—in her new book, Life on a Little-Known Planet: Dispatches from a Changing World—compares to the clatter of a manual typewriter. “Codas,” cetologists call these percussive measures. On assignment for The New Yorker in 2023, Kolbert went to sea with participants in the Cetacean Translation Initiative, a nonprofit cooperative of scientists who train large language models on recordings of sperm whale codas in hopes of deciphering them. The team was led by David Gruber, distinguished professor of Biology and Environmental Sciences at the City University of New York and CETI’s founder and president. Also aboard the research vessel and mentioned in the excerpt published here were Shane Gero, CETI’s lead field biologist; Yaly Mevorach, a graduate student; and a pair of undergraduates, Stefano Pagani and Aidan Kenny. “The profound question,” Kolbert said on the October 10, 2025 episode of The World in Time, “and it is a profound one, is: do codas function in any way as words?”
The first scientific, or semi-scientific, study of sperm whales was a pamphlet published in 1835 by a Scottish ship doctor named Thomas Beale. Called The Natural History of the Sperm Whale, it proved so popular that Beale expanded the pamphlet into a book, which was issued under the same title four years later.
At the time, sperm whale hunting was a major industry, both in Britain and in the United States. The animals were particularly prized for their spermaceti, the waxy oil that fills their gigantic heads. Spermaceti is an excellent lubricant, and, burned in a lamp, produces a clean, bright light; in Beale’s day, it could sell for five times as much as ordinary whale oil. (It is the resemblance between semen and spermaceti that accounts for the species’ embarrassing name.)
Beale believed sperm whales to be silent. “It is well known among the most experienced whalers that they never produce any nasal or vocal sounds whatever, except a trifling hissing at the time of the expiration of the spout,” he wrote. The whales, he said, were also gentle—“a most timid and inoffensive animal.” Herman Melville relied heavily on Beale in composing Moby Dick. (His personal copy of The Natural History of the Sperm Whale is now housed in Harvard’s Houghton Library.) He attributed to sperm whales a “pyramidical silence.”
“The whale has no voice,” Melville wrote. “But then again,” he went on, “what has the whale to say? Seldom have I known any profound being that had anything to say to this world, unless forced to stammer out something by way of getting a living.”
The silence of the sperm whales went unchallenged until 1957. That year, two researchers from the Woods Hole Oceanographic Institution picked up sounds from a group they’d encountered off the coast of North Carolina. They detected strings of “sharp clicks,” and speculated that these were made for the purpose of echolocation. Twenty years elapsed before one of the researchers, along with a different colleague from Woods Hole, determined that some sperm whale clicks were issued in distinctive, often repeated patterns, which the pair dubbed “codas.” Codas seemed to be exchanged between whales, and so, they reasoned, must serve some communicative purpose.
Since then, cetologists have spent thousands of hours listening to codas, trying to figure out what that function might be. Gero, who wrote his PhD thesis on vocal communication between sperm whales, told me that one of the “universal truths” about codas is their timing. There are always four seconds between the start of one coda and the beginning of the next. Roughly two of those seconds are given over to clicks; the rest is silence. Only after the pause, which may or may not be analogous to the pause a human speaker would put between words, does the clicking resume. Codas are clearly learned or, to use the term of art, socially transmitted. Whales in the eastern Pacific exchange one set of codas, those in the eastern Caribbean another, and those in the South Atlantic yet another. Baby sperm whales pick up the codas exchanged by their relatives, and before they can click them out proficiently, they “babble.”
The whales around Dominica have a repertoire of around twenty-five codas. These codas differ from one another in the number of their clicks and also in their rhythms. For example, the coda known as three regular, or 3R, consists of three clicks issued at equal intervals. The coda 7R consists of seven evenly spaced clicks. In seven increasing, or 7I, by contrast, the interval between the clicks grows longer; it’s about five-hundredths of a second between the first two clicks, and between the last two it’s twice that long.
In four decreasing, or 4D, there’s a fifth of a second between the first two clicks and only a tenth of a second between the last two. Then there are syncopated codas. The coda most frequently issued by members of Unit R, which has been dubbed 1+1+3, has a cha-cha-esque rhythm and might be rendered in English as click . . . click . . . click-click-click.
If codas are in any way comparable to words, a repertoire of twenty-five represents a pretty limited vocabulary. But, just as no one can yet say what, if anything, codas mean to sperm whales, no one can say exactly what features are significant to them. It may be that there are nuances in, say, pacing or pitch that have so far escaped human detection. Already, CETI team members have identified a new kind of signal—a single click—that may serve as some kind of punctuation mark. When whales are resting near the surface, their exchanges can last an hour or more. Even by human standards, sperm whale chatter is insistent and repetitive. “They’re talking on top of each other all the time,” Gero told me.
A snatch of dialogue recorded between two members of Unit R runs as follows. (Both Roger and Rita are adult females.)
Roger: 1+1+3
Rita: 1+1+3, 1+1+3
Roger: 9I
Rita: 1+1+3
Roger: 10I
Rita: 1+1+3, 1+1+3
Roger: 11I
Rita: 1+1+3
Roger: 10I, 11I, 1+1+3
Rita: 1+1+3
The “conversation” continues along much these same lines, until Rita finally changes her tune:
Rita: 1+1+3
Roger: 12R, 10I, 10I, 9I, 9I
Rita: 9I, 8I
A sperm whale’s head takes up nearly a third of its body; its narrow lower jaw seems borrowed from a different animal entirely; and its flippers are so small as to be almost dainty. (The formal name for the species is Physeter macrocephalus, which translates roughly as “big-headed blowhole.”) “From just about any angle,” Hal Whitehead, one of the world’s leading sperm whale experts (and Gero’s thesis adviser), has written, sperm whales appear “very strange.” I wanted to see more of these strange-looking creatures than was visible from a catamaran, and so, on my last day in Dominica, I considered going on a commercial tour that offered customers a chance to swim with whales, assuming that any could be located. In the end—partly because I sensed that Gruber disapproved of the practice—I dropped the idea.
Instead, I joined the crew on CETI 1 for what was supposed to be another round of drone tagging. After we’d been underway for about two hours, codas were picked up to the northeast. We headed in that direction and soon came upon an extraordinary sight. There were at least ten whales right off the boat’s starboard. They were all facing the same direction, and they were bunched tightly together in rows. Gero identified them as members of Unit A. The members of Unit A were originally named for characters in Margaret Atwood novels, and they include Lady Oracle, Aurora, and Rounder, Lady Oracle’s daughter.
Earlier that day, the crew on CETI 2 had spotted pilot whales, or blackfish, which are known to harass sperm whales. “This looks very defensive,” Gero said, referring to the formation.
Suddenly, someone yelled out, “Red!” A burst of scarlet spread through the water, like a great banner unfurling. No one knew what was going on. Had the pilot whales stealthily attacked? Was one of the whales in the group injured? The crowding increased until the whales were practically on top of one another.
Then a new head appeared among them. “Holy fucking shit!” Gruber exclaimed.
“Oh, my God!” Gero cried. He ran to the front of the boat, clutching his hair in amazement. “Oh, my God! Oh, my God!” The head belonged to a newborn calf, which was about twelve feet long and weighed maybe a ton. In all his years of studying sperm whales, Gero had never watched one being born. He wasn’t sure anyone ever had.
As one, the whales made a turn toward the catamaran. They were so close I got a view of their huge, eerily faceless heads and pink lower jaws. They seemed oblivious of the boat, which was now in their way. One knocked into the hull, and the foredeck shuddered.
The adults kept pushing the calf around. Its mother and her relatives pressed in so close that the baby was almost lifted out of the water. Gero began to wonder whether something had gone wrong. By now, everyone, including the captain, had gathered on the bow. Pagani and another undergraduate, Aidan Kenny, had launched two drones and were filming the action from the air. Mevorach, meanwhile, was recording the whales through a hydrophone.
To everyone’s relief, the baby began to swim on its own. Then the pilot whales showed up—dozens of them.
“I don’t like the way they’re moving,” Gruber said.
“They’re going to attack for sure,” Gero said. The pilot whales’ distinctive, wave-shaped fins slipped in and out of the water.
What followed was something out of a marine mammal Lord of the Rings. Several of the pilot whales stole in among the sperm whales. All that could be seen from the boat was a great deal of thrashing around. Out of nowhere, more than forty Fraser’s dolphins arrived on the scene. Had they come to participate in the melee or just to rubberneck? It was impossible to tell. They were smaller and thinner than the pilot whales (which, their name notwithstanding, are also technically dolphins).
“I have no prior knowledge upon which to predict what happens next,” Gero announced. After several minutes, the pilot whales retreated. The dolphins curled through the waves. The sperm whales remained bunched together. Calm reigned. Then the pilot whales made another run at the sperm whales. The water bubbled and churned.
“The pilot whales are just being pilot whales,” Gero observed. Clearly, though, in the great “struggle for existence,” everyone on board CETI 1 was on the side of the baby.
The skirmish continued. The pilot whales retreated, then closed in again. The drones began to run out of power. Pagani and Kenny piloted them back to the catamaran to exchange the batteries. These were so hot they had to be put in the boat’s refrigerator. At one point, Gero thought that he spied the new calf, still alive and well. (He would later, from the drone footage, identify the baby’s mother as Rounder.) “So that’s good news,” he called out.
The pilot whales hung around for more than two hours. Then, all at once, they were gone. The dolphins, too, swam off. “There will never be a day like this again,” Gero said as CETI 1 headed back to shore.
That evening, everyone who’d been on board CETI 1 and CETI 2 gathered at a dockside restaurant for a dinner in honor of the new calf. Gruber made a toast. He thanked the team for all its hard work. “Let’s hope we can learn the language with that baby whale,” he said.
I was sitting with Gruber and Gero at the end of a long table. In between drinks, Gruber suggested that what we had witnessed might not have been an attack. The scene, he proposed, had been more like the last act of The Lion King, when the beasts of the jungle gather to welcome the new cub.
“Three different marine mammals came together to celebrate and protect the birth of an animal with a sixteen-month gestation period,” he said. Perhaps, he hypothesized, this was a survival tactic that had evolved to protect mammalian young against sharks, which would have been attracted by so much blood and which, he pointed out, would have been much more numerous before humans began killing them off.
“You mean the baby whale was being protected by the pilot whales from the sharks that aren’t here?” Gero asked. He said he didn’t even know what it would mean to test such a theory. Gruber said they could look at the drone footage and see if the sperm whales had ever let the pilot whales near the newborn and, if so, how the pilot whales had responded. I couldn’t tell whether he was kidding or not.
“That’s a nice story,” Mevorach interjected.
“I just like to throw ideas out there,” Gruber said.
From an essay originally published in The New Yorker, September 11, 2023, and collected in Life on a Little-Known Planet by Elizabeth Kolbert. Copyright © 2025 by Elizabeth Kolbert. Published in the United States by Crown, an imprint of the Crown Publishing Group, a division of Penguin Random House LLC.