A humpback whale hovers near the surface, jaws spread wide, motionless — and there’s nothing to eat. No fish, no krill, no feeding frenzy. Just an enormous mouth held open for reasons marine biologists couldn’t explain.
The behavior is rare, energetically costly, and has puzzled researchers for years. The evidence needed to study it wasn’t locked in a laboratory or gathered from a research vessel. It was hiding in plain sight — scattered across Instagram, TikTok, and YouTube, uploaded by tourists who simply thought they’d caught something beautiful.
A mouth wide open — and no one knows why
Humpback whales are baleen whales, meaning their mouths are built for a specific purpose: eating. Those bristle-like baleen plates act as sieves, filtering large quantities of fish or krill from the water. Normally, a humpback opens its jaws in one context only — when food is involved. So when researchers began documenting cases of whales holding their mouths wide open with nothing nearby to eat, it didn’t fit the pattern.
The behavior cuts across age groups. Calves, juveniles, and adults have all been observed gaping, and it occurs across different ocean regions — suggesting it isn’t a quirk confined to one population or environment. Even so, it remains poorly documented, largely because it’s rare and unpredictable, making it nearly impossible to study through scheduled fieldwork.
What makes gaping especially puzzling is the energy involved. Holding a massive jaw open against water resistance isn’t trivial, and behaviors that costly typically have a clear payoff. Here, that payoff isn’t apparent — which is precisely what makes the behavior worth investigating.
Scrolling for science: how social media became a research tool
Rather than waiting for a research vessel to chance upon a gaping whale, the team behind the new study took a different approach. They searched Instagram, Facebook, TikTok, YouTube, X, and Bluesky using keywords and hashtags like “whale mouth open,” combing through tourist footage and wildlife photography for usable observations.
The results were substantial. Researchers identified 66 documented instances of humpback gaping captured between 2014 and 2025 — footage from boats, swimmers on whale-watching trips, and drones, offering a range of vantage points that traditional fieldwork rarely provides all at once.
The geographic spread was equally wide, reflecting how closely humpbacks are watched and how reliably tourists document what they see. Replicating that global footprint through conventional research methods would have taken years. This is what citizen science, done well, can offer: a dataset assembled from the accumulated curiosity of thousands of people who happened to be in the right place with a camera.
Patterns in the data: what the images revealed
With 66 cases to analyze, patterns began to take shape. The most significant: the majority of gaping instances occurred when other humpbacks were present. That finding alone reframed the behavior — shifting it from individual quirk to potential social signal, something happening between whales rather than within them.
The footage also showed gaping occurring both above and below the water surface. Whatever the behavior is communicating or accomplishing, it doesn’t appear limited to one medium or one type of interaction.
The age range of observed animals — from calves through adults — raises further questions. If gaping appears across developmental stages, it may be something learned over time, transmitted between individuals the way other humpback behaviors appear to be. These findings were published in the journal Animal Behavior and Cognition.
Leading theories: communication, play, or something else?
The researchers propose several possible explanations, none yet confirmed. Communication ranks among the leading candidates. Study co-author Vanessa Pirotta, a whale researcher at Macquarie University in Australia, noted that gaping has consistently appeared in social contexts. “One theory is it is a form of communication,” she told IFLScience. “When it has been seen, it has always been in a social context.”
Other hypotheses include jaw stretching, cleaning baleen of accumulated debris, and play or object exploration. The range of possibilities reflects how early this line of inquiry remains.
The social angle connects to a broader picture of humpback cognition. A separate study published this year found that humpbacks likely learn bubble-netting — the coordinated technique of using rings of bubbles to concentrate prey — by observing one another. If complex feeding strategies can be socially transmitted, it’s reasonable to ask whether gaping carries social meaning as well. No single explanation has been ruled in or out.
What tourists with smartphones are teaching marine biology
There’s a broader point embedded in this research, one that extends well beyond humpback whales. Tourism operators and recreational wildlife watchers log enormous amounts of time observing animals in the field. Pirotta acknowledged this directly: “Tourism operators and citizen scientists spend hours observing whales and are a powerful resource for capturing and reporting on behavior, using the increasingly high-quality technologies many of us have on hand.”
Smartphone cameras and consumer drones have improved considerably over the past decade. What was once blurry, unusable footage is now sharp enough to document subtle behavioral details — jaw angles, proximity to other animals, body orientation. That shift in image quality has quietly expanded what’s scientifically possible.
Humpback whales have been the subject of decades of research, conservation work, and public fascination. And yet, as this study demonstrates, even well-studied animals hold genuine mysteries. The gaping behavior wasn’t hidden in some remote habitat — it was sitting in vacation photos, waiting for someone to look carefully enough to ask what it meant. The natural world still has unanswered questions, and some are being documented right now by people who don’t yet know what they’ve captured.