Something so small as an epibiont tells you who the whale spent time with
Off the coast of Argentine Patagonia, a photographer's drone captured what the scientific record had never before confirmed: a living southern right whale bearing the biological signatures of a humpback. The tiny organisms clinging to its skin—barnacles that belong, by evolutionary logic, to another species entirely—speak to an encounter more prolonged and intimate than marine science had assumed possible between these two great animals. In the vastness of the open ocean, where so much remains unseen, a chance aerial image has quietly redrawn the boundaries of what we know about the inner lives of whales.
- A routine documentation flight over San Matías Gulf became extraordinary when a photographer noticed unfamiliar reddish structures on a southern right whale's skin—organisms that had no business being there.
- Scientists were startled: pedunculated barnacles, unmistakably characteristic of humpback whales, were confirmed on a living right whale, a cross-species transfer with no living precedent in the scientific record.
- The only prior comparable case, a dead calf found in Brazil in 2004, offered tissue samples but no insight into how the transfer happened—this living whale changes everything about what can be inferred.
- Researchers now face urgent new questions: if these species interact long enough to exchange parasites, prevailing assumptions about the brevity and insignificance of inter-species encounters at sea must be reconsidered.
- The discovery is landing as an open door—into whale ecology, migration, and social behavior—with a single drone flight reframing what a barnacle can mean as biological evidence.
Maximiliano Cartes Salas was conducting an aerial documentation flight over San Matías Gulf, Argentina, when his drone footage revealed something that would unsettle marine scientists: reddish structures clustered across the callosities of a southern right whale that did not belong there. What he had filmed were epibionts—organisms that live on whale skin—but specifically the pedunculated barnacles associated with humpback whales, not the crustaceans that southern right whales typically carry.
When biologist Magdalena Arias of CIMAS-CONICET reviewed the images, the identification was unambiguous. The barnacles were large enough to confirm even in aerial footage, and their presence on a right whale represented something with no living precedent in scientific literature. The only comparable case had been a dead southern right whale calf found in Brazil in 2004, which carried similar humpback epibionts—but that discovery, made from a deceased animal, could not reveal how the transfer had occurred or what kind of encounter had produced it.
The significance lies in what epibionts require to transfer between whales: direct, sustained physical contact. These organisms do not migrate on their own. For a southern right whale to carry a humpback's parasitic load, it must have spent considerable time in close proximity to a humpback—far longer than the fleeting, inconsequential encounters scientists had assumed characterized cross-species interactions at sea.
Arias described the epibiont as a kind of biological record, a marker written across the whale's body that speaks to where it has been and who it has been with. The drone footage, captured almost by accident, has opened new research avenues into the ecology, migration, and social behavior of both species—and suggested that the relationships between them may be far more complex and enduring than the science had previously imagined.
Maximiliano Cartes Salas was flying his drone over San Matías Gulf when he spotted something that would puzzle marine scientists for weeks to come. The photographer, who has spent years capturing aerial footage of whales during their seasonal migration, noticed reddish structures clustered across the callosities—the rough patches of skin—on a southern right whale. What looked like routine documentation became something far more significant the moment he sent the footage to researchers.
The structures Cartes Salas had filmed are called epibionts: organisms that live on the skin of whales, and they are, in most cases, species-specific. Southern right whales typically carry three types of cyamids, small crustaceans that have evolved alongside them for millennia. Humpback whales carry different epibionts entirely, including the distinctive pedunculated barnacles that were visible in Cartes Salas's drone footage. What made this discovery extraordinary was that these humpback-specific organisms were attached to a southern right whale—something never before documented in the scientific record.
Magdalena Arias, a biologist with CIMAS-CONICET, was startled when she reviewed the images. The pedunculated barnacles were unmistakable, their larger size making them identifiable even in aerial footage. Arias explained that while cyamids require microscopic examination to distinguish between species—looking for tiny spines on the abdomen—the barnacles were obvious enough to confirm. This was not a case of misidentification or ambiguous data. A southern right whale was carrying the parasitic load of a humpback whale.
The only comparable incident in scientific literature occurred in 2004 in Brazil, when a dead southern right whale calf washed ashore with similar humpback epibionts. Researchers were able to collect tissue samples and analyze them in the laboratory, confirming the cross-species transfer. But that discovery came from a deceased animal, limiting what could be learned about how the transfer had occurred. Cartes Salas's footage offered something different: evidence of a living whale that had survived the encounter, which meant the contact had been sustained enough for organisms to establish themselves and persist.
The implications are significant. Epibionts are transmitted between whales through direct contact—vertically from mother to calf within a species, and horizontally between individuals in the same population. For a southern right whale to acquire humpback epibionts, it would have required prolonged interaction with a humpback whale. Arias emphasized that scientists have long assumed such cross-species encounters, when they occur at sea, are fleeting and inconsequential. This discovery suggests otherwise. The contact was not a passing brush but something sustained enough to allow organism transfer and establishment.
What makes this finding particularly valuable is what it reveals about whale behavior in the open ocean, a realm that remains largely mysterious to marine science. Arias noted that researchers know interactions between these species happen, but the assumption has always been that they are occasional or temporary. A whale carrying another species's parasites tells a different story—it speaks to relationships that may be more complex and enduring than previously imagined. The epibiont becomes a biological record, a marker of contact that the whale carries on its skin.
The discovery has opened new research questions that extend far beyond the single whale in Cartes Salas's footage. If southern right whales and humpback whales are interacting long enough to exchange parasites, what does that mean for understanding their ecology, their migration patterns, their social structures? Arias concluded that something as small as an epibiont can tell you where a whale has been and who it has spent time with—a biological narrative written across the animal's body. The drone footage, captured almost by chance during a routine documentation flight, has become a window into relationships between whale species that science is only beginning to understand.
Notable Quotes
This type of associated organisms had never been recorded before in southern right whales and opens very interesting questions for research— Magdalena Arias, CIMAS-CONICET researcher
Something as small as an epibiont tells you the behavior of the animal—it's telling you who it spent time with and how long— Magdalena Arias
The Hearth Conversation Another angle on the story
What made this particular sighting different from the thousands of whale observations scientists have made before?
The difference is that we could see, in a single image, evidence of sustained contact between two species that shouldn't be sharing parasites. It's not just that the organisms were there—it's what their presence tells us about how long the whales were together.
So the epibiont is like a biological timestamp?
Exactly. These organisms don't just appear overnight. They establish themselves, they persist. If a southern right whale is carrying humpback parasites, it means the contact wasn't a brief encounter in passing. It was long enough for transfer to happen and for the organisms to survive on a new host.
Why does it matter whether the contact was brief or prolonged?
Because it changes how we understand whale behavior at sea. We've always thought these interactions were accidents—ships passing in the night. But if they're sustained enough to exchange parasites, we're looking at something more intentional, more social. These whales might be seeking each other out.
The 2004 case in Brazil—why couldn't that have told us the same thing?
That was a dead calf. We could confirm the parasites were there, but we couldn't know how the transfer happened or what the living whale's behavior was like. This one is alive, carrying the evidence, moving through the ocean. It's a living record.
What happens next? Do researchers try to find this whale again?
That's the question. If they can locate it, they might learn more about its movements, its associations. But even without that, this discovery opens the door to looking at whale interactions differently—to asking whether what we thought were rare accidents might actually be regular, meaningful relationships.