Sperm whales make the loudest communication sound of any animal on Earth, researchers find — but they aren't sure why.

In a new study, researchers investigated the mysterious, low-frequency clangs made by male sperm whales and found that they were louder than any known sperm whale communication signal, with the potential to be heard by other whales around 43 miles (70 kilometers) away.

They are very loud and metallic sounds that almost sound "like a jail door slamming," which is "why they are also called clangs," study first author Simone Videsen and co-author Peter Teglberg Madsen, biologists at the Center for Active Sensing with Sound at Aarhus University in Denmark, told Live Science in an email. "You feel small as a human when you hear them, as they are clearly made by something bigger than you," they said.

Sperm whales (Physeter macrocephalus) are the largest toothed predators, growing up to around 59 feet (18 meters) long. They dive deep into the ocean to hunt giant squid (Architeuthis dux) and other prey that dwell as low as 1.9 miles (3 km) below the ocean surface.

The distinctive clangs, first reported in the 1980s, are the loudest communication signal that sperm whales make, although they can produce even louder echolocation clicks to locate prey during hunts. The clangs are unusual because they are made only by males and represent an extreme form of communication that scientists still can't fully explain.

In the latest study, the researchers used hydrophones (underwater microphones) off the Seychelles to measure the sound level of the clangs. They also studied the rhythm of the signals in recordings collected in other locations, including off Sri Lanka, Norway and Scotland.

The recordings revealed that the whales kept up a slow, low-frequency rhythm, unlike the short, rhythmic clicks that both males and females make for typical social communication or the clicks used in echolocation. In fact, the rhythm was so slow that males left a gap of 5 to 10 seconds between each clang. That might not sound that impressive ‪—‬ but as far as we know, whales can't count to 10, so they are using another means to keep up this rhythm. According to the study, the whales might be relying on the echoes of the clangs bouncing off the seafloor.

Sperm whales can produce these record-breaking acoustics thanks to their ginormous noses — the largest of any animal — that dominate their massive heads, which make up about one-third of their body length. To make the clangs, male whales use their "phonic lips" ‪—‬ structures in their noses that snap together.

"They make [these noises] by forcing pressurized air through so-called phonic lips in their giant sound producing nose," Videsen and Madsen said.

The researchers proposed a few possible explanations for why the whales might be making the long-range clangs. For example, the males might be using the sounds to attract mates or scare off other males.

However, the communication may exist for another, unknown reason. In future studies, the researchers hope to learn more about this mysterious form of communication by playing recordings of the clangs underwater and seeing how nearby sperm whales respond.

Throughout his career as a composer, Jim Nollman has worked with unorthodox partners to create music. Instead of collaborating solely with human musicians, the artist has expanded his cast to include animal bandmates, and they've been making melodies together for more than 50 years.

Nollman's new album, "Orcas' Greatest Hits," will be released Aug. 14 by the music label Smithsonian Folkways Recordings. As the title suggests, the album is a collection of songs centered around orca (Orcinus orca) vocalizations.

Nollman now lives in Friday Harbor, Washington, but he recorded these sounds off the coast of British Columbia between 1985 and 2002, using underwater microphones called hydrophones. The vocalizations weren't random calls that Nollman overheard; rather, he prompted the orcas to "sing" by broadcasting his and fellow musicians' music into the water via underwater speakers. The artists kept the volume at a reasonable level to protect the orcas and performed after dark to avoid motorboat sounds.

However, orcas weren't Nollman's first animal bandmates. Fresh out of Tufts University in the 1970s, he made music with various animals, including turkeys, wolves and dolphins. To learn more, we spoke with Nollman about his career, including several years he spent consulting with the U.S. Navy, and the extraordinary interactions he's had with whales and other creatures.

Sascha Pare: How did you first start making music with animals?

Jim Nollman: In my latter year at university, I got involved in the theater, doing all the music for all their plays. I soon got into John Cage [an American composer known for his innovative approaches to sound] ‪—‬ first in Boston, and then in the San Francisco Bay Area when I moved there. I got to know some of the avant-garde music people, especially in Berkeley, because there was a big movement there [centered around California's KPFA Radio].

I'd been in Mexico, playing flute, and the turkeys next door would always gobble on a certain high note and at a certain volume. I said [to an editor at KPFA], "Why don't you send me to a turkey farm? I'd like to do a Thanksgiving Day piece." He gave me a sound man and a Nagra tape recorder. I remember vividly, because having a Nagra after just getting out of college was a big deal for me. I was into technology. [Editor's note: Nagra is a Swiss brand of portable audio recorders.]

The turkey farm had 300 turkeys, and I immediately learned from the owner that it's really only the males that gobble. He kept the males and the females separate, so he put me into the fenced-in area where the males were. I started singing, and I could control them. The turkeys closest to me would start, and the gobble would go out to the edge of the 300 birds. And then it would come back, and then they would all stop. I was singing "Froggie Went A-Courtin'," which is an old American folk song [originally from Scotland] about animals. I sang 30 or 40 verses of this song and controlled the turkeys.

I was around 24 years old, and I had a hit. I knew I wanted to be a musician, but I had some major flaws to be a performer, because I didn't like being the center of attention. I'm kind of an introvert. That's a loser if you're trying to be a singer-songwriter. I loved writing tunes and playing them, but not in front of a big audience. This [recording tunes in nature with animals] was a way to get into music.

After the turkeys, I wondered if I should try making music with animals again. I tried it with kangaroo rats [Dipodomys deserti], which build these burrows like Trinidad steel drums. Kangaroo rats only come out at night, and they thump to each other in their burrow systems, which are tuned — it seemed to me, anyway, that each place in the burrow had a different tone — and they communicate with one another.

Then, I went to a wolf preserve. I realized that the wolves did two or three howl sessions in the morning around dawn and two or three at night. The wolves wouldn't play with me if I was out of their key. If I played a flat note, they would stop and basically tell me, "We don't mind if you're playing in our pack, but you've got to do it right." That was a big lesson for me, and that's how I got into it.

SP: Your new album features orcas. Did you always have a sweet spot for orcas, or is there another animal you preferred working with?

JN: No, I don't have a sweet spot for orcas. I recorded orcas for 15 years, and I had lots of recordings, most of which I never really listened to, because I didn't know what to do with them. At some point, I decided that "I can't do anything more with the orcas, and I don't like going to whale conferences and being this authority," because it wasn't about that for me.

[After years of recording orcas], I started going to the Arctic ‪—‬ because I wanted to go to the Arctic and because beluga whales [Delphinapterus leucas] were there, and they seemed like the opposites of orcas. The orcas were very much in tight families traveling together and making very simple calls that had deep meaning. To have their echolocation against a speaker at midnight could be like being in a war zone. It was so loud; we had speakers blow out sometimes.

The beluga whales were the antithesis of that. It seemed like they all were talking at the same time, and they all seemed to know what everybody else was saying. This is my speculation. They used sound as their family anchor, and I had no idea if they all understood each other talking. But it was very much more animated than what the orcas were doing. I would say 50% of the orca calls were just two notes; they were D to C, and back to D. And they would do that all day long, some of them. Beluga whales sometimes sounded like belly laughs. They made the weirdest sounds, and I loved it.

I went everywhere in the Arctic. I started out in the first year going to Nome [Alaska] in the Bering Strait, and then I went east to the Mackenzie River delta in northern Canada on the Beaufort Sea. Then, I went to Baffin Island in the Canadian High Arctic. In every place I went, limited beluga populations were crashing. At some point, I realized this was a complete loser. I pretty much gave it up until I met some people from Finland who said, "You should try it in Russia." The Soviet Union had recently crashed, and they were opening up all the places where they had their gulags [forced labor camps] and their nuclear fleet. The Solovetsky Islands were loaded with beluga whales that hadn't seen people in 70 years. I went there, and I had a great time with the beluga whales.

SP: What is your favorite memory of working with orcas or beluga whales?

JN: Six or eight years ago, somebody brought me and a bunch of other artists up to Hudson Bay [in Canada], basically to emulate what I'd done for so many years [artistic residencies to experiment with whale sounds]. I was the mentor for everybody. I liked that role. We were confronted with beluga whales, and I said, "I don't really want to play the guitar or the mandolin with the beluga whales, because I've tried that all over the Arctic and I've never had much success. I'm going to put my head in the water and blow bubbles."

The beluga whale came up, and it wrapped its mouth around my face. It did the same thing to the woman who was blowing bubbles on the other side of the kayak we were on. That was maybe the most fun thing I ever did with cetaceans. I wasn't worried at all. I've had the same thing happen with giraffes. I was in Texas at this game farm, and this giraffe came and licked my whole face with its giant tongue. It was really quite wonderful.

SP: The oldest recordings in the new album are 40 years old, and you said you hadn't listened to all of them before making the album. What was it like hearing them after all these years?

JN: I had 65 hours of tapes, and I listened to them over three or four months. Ninety percent of it was rubbish; it was just repetitive, and the whales would get into their D-to-C-to-D call routine. I wanted something where there was a groove, or some kind of magic going on that was inexplicable.

I started choosing some sequences. I thought it was only a certain level of connection that we'd created, but a couple of the things that I listened to when I was in that process blew me away. The one where I was playing James Brown riffs into the water ‪—‬ that was very strong for me. I'd never heard that before. I was discovering new stuff by giving it a close listen.

There's one where I was being filmed by National Geographic, and it was just me and a guy on a big boat cruising the waters. I started playing a country blues bottleneck on the guitar. [Editor's note: A bottleneck in country blues is a guitar-playing technique where a hard object is placed on a finger and glided along the strings.] The whales only did this a couple of times, but they would come in with a chord change. Say I'm playing in a key of D; they would come up and play the G in perfect time. I was impressed by that.

SP: Did you ever play the recordings of you and the orcas back to the orcas?

JN: No, because the recording can't answer the whales. I was trying to make a telephone connection, so it has to be two things talking to each other. To play a recording would be like me saying, "Let's stop this interview now, and I'm going to put on something of me giving an interview to somebody I spoke to yesterday." You wouldn't like that, and I don't think the whales would have liked that either if I did it to them. It had to be direct. I had many people who were very ardent or passionate about singing or reciting poetry — one guy wanted to sing Jewish death prayers to the whales. But the whales didn't come.

SP: Is part of why you've been so successful at making music with animals that they particularly like you?

JN: Some animals like me. I definitely got through to the orcas. I could tell that, because I had an interim of eight years between doing it with the big communities [of artists] and going out alone with the orcas. They were the same orcas, and they definitely knew who I was the first time I put sound in the water again. That's when that country blues episode happened. We were all much more relaxed with each other. The second time was great. It was also a tragedy, because the whales had lost their residence to the loss of salmon [in the northeast Pacific Ocean], and they were way out of their range.

SP: Your work with orcas and other whales landed you a job with the U.S. Navy in 2011. How did that happen, and what was your role?

JN: I was doing underwater concerts in the 1990s. I was invited to Kodiak Island, which is a large island off the coast of southern Alaska. They wanted me to do an underwater concert. At the time of this festival, in which I was performing, the U.S. Navy was sending ballistic missiles from Southern California to the waters off Kodiak Island for testing. This was destroying the halibut [Hippoglossus stenolepis] fishery on Kodiak Island, because the fishermen couldn't go into this area, suddenly.

The Navy sent a guy who was part of this ballistic missile thing but also had a PR background. He said, "Can I speak before your concert?" I said, "You can speak about whatever you want, but you've got to get in the water. That's the payment you have to give me: Get in the water and hear all this music that I've created."

He was blown away. I had a fan. He took me out for dinner and asked me if I had any ideas about solving this great scandal that was enveloping the Navy at the time, which was the killing of mostly beaked whales during mid-frequency sonar exercises, mostly in the Bahamas, in this hole in the ocean that's there. Nobody had a solution, so he wanted me to be on the team. I said, "Sure, I'll be on the team." It was like somebody asking me to play for the New York Yankees or something — completely odd, but I thought, "OK, I'll try that."

He called me back two years later, saying, "We have our money, and we want you to come to the Groton submarine base [in Connecticut], where we'll have our first meeting with submarine captains, Ph.D. sonar engineers and a few whale biologists." That went on for seven years. I took the job seriously. I told them that I thought we could solve it in five minutes. I said, "All you need to do is take care. If you see whales in the vicinity, don't exercise on that day." This sounds so totally obvious, but the fact was that he [the PR man] was contending with a Navy establishment that believed that the Navy could do anything to save the American people from being bombed or wrecked. They didn't see whales as anything but collateral damage.

SP: Do you have a favorite song on the new album?

JN: I like "The Three Jimmies." I never knew that James Brown's guitar player was named Jimmy Nolen — I mean, that's really outrageous. So, it's the three Jimmies, right? I really like the music, and I like the piano player [Jonathan Churcher], who plays one note every three or four bars. The response of the whales is also brilliant, I think. There's one part where the whale starts to echolocate, which is the way they see the world; it's their perceptional tool. The whale starts clicking in time with the beat that I'm playing on the guitar. That only happened once in 65 hours of recordings, and I thought that was pretty unusual.

SP: What's next for you after "Orcas' Greatest Hits"?

JN: I'm composing new music, and I'm hoping I'm at least breaking even [with the new album] so that they [Smithsonian Folkways Recordings] can do the next one, which is called the "Cowbird Variations." The cowbirds are basically the bottom voice, maybe the part that's played by bass in pop music. Everything else is other birds and insects called treehoppers. It has this very primitive sound to it.

I love doing this music with cowbirds, because cowbirds have a horrible reputation. They lay their eggs in other birds' nests, and when the eggs hatch, the baby cowbirds knock all the birds in the nest out and kill them. Then, the parents — juncos, where I live — end up raising the cowbirds. These birds have a terrible reputation, but they make one of the strangest sounds in nature — so that's why I chose them.

This interview has been condensed and edited lightly for clarity.

A camera drone operator captured footage of a humpback whale giving birth off the north coast of New South Wales in what is thought to be a world first.

Alexander Forrest, a commercial drone pilot for the Organisation for the Rescue and Research of Cetaceans in Australia (ORRCA), was conducting aerial observations of migrating humpback whales (Megaptera novaeangliae) on July 28. ORRCA is a nonprofit organization focused on the rescue, conservation and welfare of marine mammals.

During the survey, Forrest noticed a whale swimming slightly behind her pod and going unusually slowly. Then, he saw her give birth.

"It's incredibly rare to see a moment like this in the ocean. It's a very rarely documented encounter," Forrest told Live Science. "It's the first drone video as far as we know of a full humpback whale live birth. It gives critical inside moments in the first moments of a calf's life, and also discovers the behaviour of a new humpback whale mother and her freshly newborn calf."

An ORRCA spokesperson said that this is only the fourth time the phenomenon of a humpback whale giving birth had been filmed, in general. Scientists also have footage of other whale births, including a gray whale (Eschrichtius robustus) birth filmed off the coast of California and a sperm whale (Physeter macrocephalus) recorded giving birth in the Caribbean.

The drone video shows the newborn whale surface from blood-reddened water for its first breath. The mother then turns back to reunite with it. The scene was filmed around 0.4 miles (700 meters) from the shore at Kingscliff in northeastern New South Wales.

The birth is "a symbol of one of the strongest conservation efforts in history, returning humpback whales from near extinction to nearly 50,000 on the New South Wales coast," Forrest said. Gathering data on this humpback whale population is critical to "discovering more about where they birth, what happens when they birth, and what those early moments look like."

The footage will now be analyzed so that a report on the observation can be peer-reviewed and published in a scientific journal. Notably, the mother whale was trailing behind her pod when she gave birth, a detail biologists will compare with observations of other birthing whales that were accompanied by members of their pod. For instance, the 2023 drone footage of the sperm whale giving birth showed that she had 10 adult females near her that formed a protective circle and took turns lifting the calf up so it could breathe at the water's surface.

Throughout their first weeks, calves stay close to their mothers and learn critical behaviors, such as breathing at the surface.

"Humpback whales seem to have an incredible maternal bond with their offspring," Forrest said. "There is an 11-month period where this calf will be raised and feeding on very nutrient-rich milk until it is a yearling and can fend for itself."

A newborn humpback whale calf weighs 1 to 1.5 tons (900 to 1,360 kilograms) and measures roughly 10 to 16 feet (3 to 5 meters) in length. While feeding on its mother's milk, the calf will gain 100 pounds (45 kg) a day and develop the strength and food storage it needs for its first migration. Humpback whales undertake one of the longest migrations of any mammal, travelling up to 5,000 miles (8,000 kilometers) each way between the cold waters of the poles to warm tropical breeding grounds.

A pod of killer whales has sunk another yacht off northwestern Spain, reinforcing a bizarre pattern of vessel encounters that has stretched on for more than six years along the Iberian coast.

In the incident, reported Friday (July 24), the whales destroyed the rudder of a 46-foot-long (14 meters) Swedish-flagged yacht off Galicia in northwestern Spain, forcing the two people aboard to send a mayday call. A Spanish coastguard vessel towed them to safety, Spain-based news outlet Sur in English reported.

The incident came after several other encounters in the same waters earlier that week, including one in which a pleasure craft called the Idem sank near Estaca de Bares, the northernmost point of the Iberian Peninsula. The ship sank after the killer whales, also known as orcas (Orcinus orca), destroyed its rudder. Both occupants were rescued.

That makes the Idem at least the eighth boat lost to these encounters since they began, according to groups that track the incidents. More than 700 interactions between orcas and vessels have been logged since 2020, ranging from a brief nudge to a multihour rudder-ramming session, according to the Atlantic Orca Working Group, the Spanish-Portuguese research collective that has coordinated data collection on the phenomenon from the start.

Researchers have identified roughly 15 individual killer whales involved in these incidents, out of an Iberian subpopulation of fewer than 50. The group is so small that the International Union for Conservation of Nature lists it as critically endangered, as it is dependent mainly on Atlantic bluefin tuna for its food.

The family-like cluster is thought to be led by a female known as White Gladis. That name comes from an early theory researchers themselves once floated: that White Gladis suffered some kind of traumatic run-in with a boat and that the encounter flipped a behavioral switch, with her being the first in the group to start ramming rudders.

Alfredo López Fernandez, a biologist with the Atlantic Orca Working Group, told Live Science in 2023 that this kind of defensive, trauma-driven origin was gaining traction among researchers at the time. But "defensive" isn't "vengeful" — and the idea has since curdled online into a punchier revenge story most scientists studying the population don't endorse.

So why do orcas go after the boats? Nobody knows for certain, but the leading explanation is simple: Orcas are some of the most social animals on the planet, and social animals pick up habits from one another the way trends spread through a friend group. Researchers describe the behavior as socially learned — young orcas appear to watch adults ram a rudder and then try it themselves, and the habit has spread through the group over time.

A 2022 study in the journal Marine Mammal Science found that the killer whales usually targeted sailing boats and often lost interest after striking the rudder and causing the boat to stop.

None of that makes the encounters any less disruptive for the people living through them. The standard guidance from authorities like the Maritime Safety and Rescue Society and the Atlantic Orca Working Group, refined over repeated encounters, is to cut the engine, drop the sails if possible, disengage the autopilot, and let go of the wheel entirely, giving the orcas nothing to push against. Boats that follow this protocol tend to sustain less damage than those that don’t.

Sailors are asked to report every encounter. Each one adds to the data scientists are using to try to solve a years-long mystery.

One of the ocean's most intelligent and aggressive predators has once again surprised scientists with a curious new behavior. In the Gulf of California, researchers witnessed orcas working together to smash dead sunfish into bits — a suspected food processing technique that makes it easier for younger whales to feed on the enormous bony fish that weigh up to 4,400 pounds (2,000 kilograms).

In two separate encounters, one orca gripped a sharp-tail sunfish (Masturus lanceolatus) while another orca charged toward the fish. The first whale released the carcass just before impact, allowing its companion to slam into the fish at high speed and scatter fragments of fish flesh throughout the water.

"It was unlike anything I'd witnessed before," Kathryn Ayres, a scientist at the conservation nonprofit Beneath the Waves told Live Science in an email. "As a scientist, moments like this are incredibly exciting because you realize you're observing something that may never have been documented in detail before — as you can tell in the video!"

Ayres and her colleagues dubbed the behavior "ram-to-fragment." Their observations, published July 23 in the journal Frontiers in Ethology, suggest the killer whales were not trying to kill the sunfish, which were already dead and appeared to have been disembowelled. Instead, the orcas may have been breaking down the bulky carcasses so members of the group, particularly younger animals, could feed more easily.

Hunting in action

The first encounter Ayres observed took place in July 2024 near an offshore seamount off Baja California Sur, Mexico. An adult female orca held a sharp-tail sunfish by its tail-like clavus, or rudder, while an adult male orca accelerated toward it, belly-up. The female released the fish an instant before the male struck.

The collision produced a loud noise and caused the sunfish's tissue to disintegrate. In the video, Ayres' shock is evident as she can be heard exclaiming, "Oh my god!"

A juvenile orca then swam into the cloud of suspended flesh and ate the smaller pieces, while the adults fed on what remained of the main carcass.

A second encounter, which the researchers credited diver Héctor Franz for filming in September 2025, followed much of the same sequence. One adult orca stabilized the sunfish, another rammed it and a calf later pulled tissue from the broken carcass.

Ayres had previously watched orcas hunt ocean sunfish (Mola mola), but this was different.

"I had also seen orcas ram their prey previously, but I had never witnessed an impact powerful enough to completely fragment the tissue like this," Ayres said. "That was what made this observation so remarkable."

The maneuver resembled coordinated attacks Ayres and her team had previously documented, in which orcas confronted whale sharks (Rhincodon typus) — the largest living fish — in the Gulf of California. In those hunts, some orcas took turns ramming it.

Why make fish confetti?

Ramming is not a new killer whale hunting technique, said Matt Hansen, a postdoctoral researcher at the Leibniz Institute of Freshwater Ecology and Inland Fisheries who was not involved in the study. However, the hold-and-release sequences and shattering of carcasses may be new, Hansen told Live Science in an email.

The researchers proposed several possible explanations for the behavior. The predominant assumption is that the adults were processing food for younger whales. Orcas frequently tear apart prey and share portions with calves and juveniles, and in both newly described encounters, young killer whales were present.

But two observations are not enough to show that the adults were deliberately feeding or teaching the youngsters, Heather Hill, a professor and chair of psychology at St. Mary's University in Texas who was not involved in the research, told Live Science in an email.

"Whether or not it represents parental investment, observational learning, or distribution of resources remains circumstantial in my opinion," she said.

The researchers also suggested that the behavior could have been playful. Orcas are highly intelligent and social, and they sometimes manipulate, toss or strike prey without immediately eating it. However, Hill said that the two encounters appeared more practical than playful.

"If it was for fun, I would have expected multiple attempts made with variations in speed, point of contact, force of impact, and initiators because the point of playing is to try different things and not destroy the toy too soon," she said. "Since it appears that these events were 'one and done' so to speak, probably less playful and more functional — to eat the fish and maybe to model a foraging technique and possibly to share resources with the younger animal."

The study authors also raise a more speculative possibility that dispersing the sunfish's microbe-rich skin and gelatinous tissue could somehow affect the surrounding water or expose the orcas to potentially beneficial microbes. But what that benefit might be is unclear.

"I don't see how dispersing the skin into the water column would have a different effect from eating it," Hansen said. "Unless the authors are suggesting [the orcas] are using it like a lotion on their own skin? Who knows, the world is weird and wonderful."

Orca quiz: Will you sink or swim?

An isolated population of sperm whales in the Mediterranean Sea are splitting into two distinct groups with different dialects, a new study reveals. This shift has likely been happening for thousands of years, as two groups split from an initial single population.

The findings, published Tuesday (June 23) in the journal Proceedings of the Royal Society B: Biological Sciences, are providing a rare insight into the process of different dialects emerging among non-human species.

The sperm whales (Physeter macrocephalus) live in small social units of females and young, and they associate with other groups in the same area. They use social vocalizations called codas ‪—‬ shortpatterns of clicks ‪—‬ to communicate. The particular codas they use identify them as being part of the same cultural group.

Taylor Hersh, a researcher in the School of Biological Sciences at the University of Bristol in the U.K. and first author of the research, and her colleagues have analyzed codas recorded over almost 20 years in the Mediterranean, where there is a unique population of a few thousand sperm whales, to see if they all use the same dialect.

Sperm whales entered the Mediterranean via the Strait of Gibraltar about 20,000 years ago, and they have spread throughout the area. The whales rarely leave the sea ‪—‬ even males, which normally migrate. Other sperm whales don't seem to enter often, either, so the Mediterranean ones are effectively isolated from other populations and are considered an endangered subpopulation.

"The sperm whales in the Mediterranean are really cool," Hersh told Live Science. "I've always thought of them as the weirdos of the sperm whale world in that they don't leave through the Strait of Gibraltar even though they could. They are unique, and for a long time, they were also thought to be acoustically unique."

The thinking was that all the sperm whales in the Mediterranean belonged to the same clan, identified by their use of a single coda 90% of the time. This coda consists of three clicks and then a pause before the fourth and final click ‪—‬ a pattern called the three-plus-one type.

But the analysis by Hersh's team of 5,291 codas recorded between 2003 and 2021 revealed that sperm whales living in the eastern Mediterranean around the Hellenic Trench, off Greece, have a slightly different dialect from that used by animals in the western basin around Spain's Balearic Islands.

The eastern whales produce a distinct form of the three-plus-one coda. "It's a very similar pattern of clicks, but it's much, much faster," Hersh said.

In some recordings, whales in the eastern Mediterranean produced the slower coda, showing they were familiar with both dialects.

"The western sperm whales religiously stick to their dialect, but there were four instances of eastern whales using the western dialect," Hersh said. "The question of why is still an open one. Their dialect seems to be a lot more diverse than we expected. They do occasionally make those slow three-plus-one codas, but they make a lot of other coda types, too."

Hersh hopes further recordings alongside records that tie individual whales to sounds and events might help elucidate why the whales switch between dialects.

"It's exciting to see this study showing different populations behaving closely, but also differently," said Gašper Beguš, linguistics lead at Project CETI, a nonprofit organization that aims to translate the communication of sperm whales.

The study paints a picture of sperm whales progressively occupying the Mediterranean from west to east, with the dialect of one group gradually changing. "The groups in the east clearly remember the western dialect because they have these 'throwback' days," Hersh said.

It's still a mystery how and why these dialects evolved.

"Every speech is a dialect; the question is how did they arise and why?" said Beguš, who wasn't involved in the new study. He said the historical change in habitat does help to show which dialect came first. "In the Mediterranean, maybe they're forming different groups, so that's why they're trying to distinguish themselves," he told Live Science, giving the parallel of young people who distinguish themselves from previous generations by coming up with new slang.

"It's possible that these two groups with repertoires that are very similar but still distinctive could represent a sort of midway phase,” Ellen Jacobs, a marine biologist at Aarhus University in Denmark who wasn't involved in the research, told Live Science via email.

"Changes in the rhythm might be a very feasible and meaningful way for coda signals to start to diverge," she said, like the way the English words "How do you do?" got mashed together until they morphed into "howdy."

The timescale on which a sperm whale dialect develops is uncertain, but it's likely a slow process, according to Hersh. "It's probably happening on the scale of hundreds and thousands of years, because sperm whales can live into their 60s and 70s. And this study is looking over 19 years of data, and that's just a snapshot of one animal's life," Hersh said.

This means the eastern whale dialect was conceivably emerging in the Mediterranean Sea as famous human civilizations were speaking different languages on the surrounding lands, including when the ancient Greeks and Romans were rising and then falling.

"Maybe if we could leave them for another 10,000 years, we would come back to find the completely separated dialects of clans," Jacobs said.