In the summer of 2023, off the coast of the Caribbean island of Dominica, a newborn sperm whale popped its head above the water and took its first breaths. On board a nearby boat, researchers laughed and cheered as they realized they’d just witnessed a birth. Shane Gero was among them. “I’ll remember that whole sequence of events forever,” he said. At one point later in the day, it started raining, but he didn’t seek shelter in the boat’s cabin. He stayed standing at the stern, filled with wonder and gratitude as he watched the whale family.
“That whole thing impacted me deeply,” said Gero, who has been studying sperm whales off the coast of Dominica since 2005. The whale who’d given birth was nicknamed Rounder. Gero first met her when she was a baby and had watched her grow up. His team will name the new calf once it is a few years old. “Each one of these animals is its own being,” he said. “They’re unique individuals.”
When sperm whales interact, they make clicking sounds that sound a bit like techno music or Morse code, Gero said. Scientists call them codas. Sperm whales use codas to identify themselves and the clan they belong to. But Gero and others think there could be more to these sounds. Could the whales be talking to each other?
The search for other intelligence here on Earth
In 2020, Gero became the biology lead for a new nonprofit science organization called Project CETI—short for Cetacean Translation Initiative. Researchers at the organization use AI and other technology to decode sperm whale sounds. The name is a play on SETI, which is the Search for Extraterrestrial Intelligence. “We feel like we’re in search for inter-terrestrial intelligence,” David Gruber, CETI’s founder and president, said.
Just before the birth, Gero noted, the whales were unusually quiet. As they resumed their clicking, the team’s equipment recorded “new codas” they hadn’t heard before, Gruber said. CETI hasn’t yet published these results, but the team has collected and published evidence that the whales’ communication system is “vastly more complicated than we ever imagined,” Gruber said. “I feel that we’re really at the tip of the iceberg of our understanding.”
It’s easy to imagine the whales clicking to welcome the new baby or decide who should hold it. But for now, we can only guess at what whales might talk about, if they are actually talking at all.
The idea that codas act like the words of a human language is controversial. Luke Rendell, a biologist at the University of St. Andrews in Scotland, has studied sperm whales for almost three decades. Rendell and his colleague Hal Whitehead were the first to show that sperm whales have cultures with unique dialects. And they pass down knowledge on how to survive in their part of the ocean.
However, he thinks telling people we could learn to talk with these whales is making “an unfortunate and unjustified promise.” Scientists have been studying the communication of other species, including many kinds of whales and dolphins, for decades. If any of these animals had a language, Rendell said, “I’m convinced we’d know about it by now.” Still, he agrees that there’s much more to learn about sperm whales, their communication system, and their culture.
A sperm whale returns to the water after surfacing for air. | Photo courtesy of Amanda Cotton
A treasure trove of data
Today’s AI models use machine learning to find patterns in data. They’ve learned to converse in numerous human languages and translate among them. Perhaps AI could help people discover patterns in sperm whale communication that we couldn’t find on our own.
In general, the more data an AI model has to work with, the better job it will do. Today’s leading AI models train on millions or even billions of examples of human text, speech, or other content. We have far fewer examples of whale sounds. So the first step for project CETI is capturing a treasure trove of data about sperm whales.
To do this, drones record video above water. Beneath the water, underwater microphones called hydrophones capture codas. Some hydrophones hang from a long cable attached to a floating whale listening station. Others move, either towed by the research boats or on board robotic gliders that follow whales to record their sounds. However, Gruber said, “the best sound we get is when [the device] is right on the whale.”
For that, the team uses tags that suction onto a whale’s body. These tags also capture heart rate, depth, temperature, and body position. Time stamps help the researchers sync up data from all these different sources. The CETI biologists share this pile of data with other team members from very different scientific backgrounds.
In 2024, Daniela Rus, a computer scientist at the Massachusetts Institute of Technology, and colleagues announced a sperm whale “alphabet.” Biologists had already known that the number of clicks in a coda and the timing between clicks matter in sperm whale communication. The new paper revealed other aspects of codas that seem important, including subtle changes in timing or the addition of extra clicks to a common pattern.
“We identified hundreds of distinct codas, far more than the handful previously recognized,” Rus said. But these weren’t just random collections of sounds. Sperm whales put complex codas together in predictable ways, following rules. This was “an important step toward understanding [codas] as a true language-like system,” Rus continued.
Language, music, or something else entirely?
Rendell pointed out that none of this AI-based research into whale communication has revealed what the clicks might mean to the whales. And he doesn’t think “a really big computer” can get us there. Even when looking at human languages, AI models spot patterns but don’t understand meaning. “Unless we get to the meaning,” Rendell said, “it doesn’t matter whether it looks like language or not.”
In addition, assuming that sperm whale clicks are a language will actually limit what we’re able to understand about these sounds, he said. From his extensive experience, there are many aspects of sperm whale communication that do not resemble human language at all. For example, sperm whales often click over one another, matching each other’s rhythms. It’s more like chorusing or dueting than conversing, Rendell said in a talk last year.
Perhaps the clicks are closer to music or art than language. Rendell noted that in human societies, we dance and make music together to help us feel more connected and relaxed. It makes sense to him that codas might play a similar role in sperm whale cultures. That’s because they need to come together as a group to fend off orca attacks and raise their young.
Saving whale cultures
Rendell and Project CETI’s scientists agree on one very important thing: Humanity should do more to protect whales, their cultures, and the ocean habitats they call home. Some people have argued that if we could talk to whales, we could ask them what they need from our conservation efforts. Rendell rejects this idea. He said we already know exactly what the whales would ask for. “They’re going to say, ‘Stop killing us.’ They’re going to say, ‘Stop polluting us.’ They’re going to say, ‘Be quiet for a while.’”
Gero and Gruber both feel that CETI’s main contribution to whale conservation will come from getting more people to care about sperm whales. And this is already happening. In 2025, Dominica established the world’s first sperm whale preserve.
“Basically, it separates ships from whales,” Gero said. He first began working on guidelines for sperm whale conservation in the area in the 2010s. But the arrival of Project CETI helped accelerate this effort, he said. Suddenly, a lot more people were paying attention to the sperm whales in the area. “I think it had a big influence [on the preserve opening],” he said.
In some ways, CETI’s efforts mirror those of Roger and Katy Payne, who released an album called Songs of the Humpback Whale in the 1970s. The haunting sounds made many people feel a kinship with whales, and a global movement to save them ensued, leading to new laws and regulations. “Understanding is not just about translation—it’s about listening, about honoring another way of being,” Rus said. “I still don’t understand what they’re saying—but I’ve come to respect that they’re saying something, and that changes everything.”