Humpback Whales Sometimes Hold Their Mouths Open for No Clear Reason. Tourists Are Helping Scientists Understand the Rare Behavior

A trove of photos and videos gathered from social media has helped researchers propose a few possible reasons for the seldom documented action, called “gaping,” including communication, jaw stretching and play

Margherita Bassi | Daily Correspondent

May 18, 2026 10:00 a.m.

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Humpback whales sometimes hang out with their mouths wide open for no apparent reason. To figure out why they engage in the energetically costly behavior, researchers turned to an unusual source for help: social media.

In a study published in the May issue of the journal Animal Behavior and Cognition, researchers collected dozens of observations of the rarely seen behavior captured by tourists and posted on social media. The trove of data highlights the value of citizen scientists and helped the team propose some possible purposes of humpback gaping, such as communication, stretching and play.

Humpbacks and other whales with baleen—bristle-like structures in their mouths that act like sieves—usually open their jaws when eating, says Olaf Meynecke, a marine ecologist at Griffith University in Australia, who did not participate in the study, to the Guardian’s Ima Caldwell.

“Concentrated prey, either fish or krill on the surface, is being taken in by [the whale] coming from the depth and lunging out with a wide-open mouth,” he says. “Humpback whales can achieve this by working together to create rings of bubbles, forcing prey to concentrate on the surface and then coordinating amongst each other [to determine] who is allowed to get the lunge from the middle.”

But occasionally, humpbacks have been spotted opening wide when food isn’t around. Given that whales are a popular photography subject, especially for tourists, the researchers behind the new study thought that images and videos shared on social media might hold valuable observations of humpback gaping.

So, the team searched Instagram, Facebook, TikTok, YouTube, X and Bluesky for evidence of the rare behavior using key terms and hashtags such as “whale mouth open.” That yielded 66 instances of gaping all over the globe, recorded from boats, swimming-with-whale activities and flying drones.

The observations, posted between 2014 and 2025, included gaping above and below the water, and involved calves, juveniles and adults. The relatively large dataset helped the researchers find some patterns among the gaping whales. For instance, most instances occurred when other humpbacks were around.

Gaping humpback whales observed through citizen science Pirotta et al. 2026

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“Why would a whale decide to open its mouth without food? We assume it’s energetically expensive,” study co-author Vanessa Pirotta, a whale researcher at Macquarie University in Australia, tells IFLScience’s Stephen Luntz. “One theory is it is a form of communication,” she says. “When it has been seen, it has always been in a social context.”

Based on the observations, some other possible reasons for the behavior include jaw stretching, cleaning baleen of debris, or playing with or exploring objects in the water.

Ultimately, the study stands as a reminder that even well-known animals still hold their secrets, and that citizen scientists can play an important role in unraveling them.

“Just when we think we know a lot about humpback whales, we don’t,” Pirotta says in a statement. “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.”

Margherita Bassi | Read More

Margherita Bassi is a freelance journalist and trilingual storyteller. Her work has appeared in publications including BBC Travel, Discover magazine, Live Science, Atlas Obscura and Hidden Compass.