Why Do Humpback Whales Open Their Mouths? 66 Clues

The researchers found their reports on social media and around the internet. People had seen the behaviour from boats, while swimming and from drones. The authors offer several possible explanations, but they did not solve the mystery. The most accurate answer today is this: we have good observations, and more than one reasonable idea.

What does “gaping” mean?

In the paper, gaping means a whale opens its mouth wide outside known feeding areas, with no clear feeding reason. The researchers collected 36 observations from boats above the water, 24 underwater observations from swim-with operations and six from drones. Some underwater examples included “jaw popping”, when the movement of the mouth made a sound.

The number 66 counts reported observations. It is not 66 different whales. Some may show the same animal, and all the material came from public online content. So this is a first look at a rare behaviour, not a population survey.

This is where citizen science shines. Someone notices something odd and shares it, and researchers can then ask a better question. It is also why the evidence needs careful reading.

So why might a humpback whale open its mouth without feeding?

The authors suggest a few possibilities. Gaping may be social or playful, or a way of communicating. In calves, it might be linked to stretching the jaw around suckling, or to exploring floating debris. In some surface behaviours, the jaw could also simply fall open because of gravity.

These are hypotheses, not confirmed reasons. One movement can mean different things in different moments, and a camera rarely catches every clue a researcher would need.

The study says gaping was mostly seen when other whales were nearby and outside known feeding routines. That is an interesting pattern, but it does not prove a social purpose. “May be social” is less catchy than “whales talk with their mouths”. It is much closer to what the evidence says.

Can you see it on a whale trip?

Maybe. But never treat it as a show to ask for. Researchers found examples in tourist footage. That does not mean guests should get closer, jump in or fly a drone to film it.

The most useful thing visitors can do is watch without directing the scene. Keep your distance and follow local rules, which can change, so check them on the spot. Leave the interpreting to researchers. A strange behaviour is still the whale’s own business, not an invitation. Wildlife encounters are unpredictable. Whale watching should always follow local regulations and experienced professional guidance.

For humpback migration, songs and the differences between populations, see our humpback whale guide. To learn how whale research and conservation groups work, read about whale conservation organisations.

For now the answer is beautifully unfinished. Sixty-six clues, several possible explanations, and an animal still keeping part of its life to itself. You can follow the questions researchers are still asking in the Ocean Atlas.

Questions people ask

Wildlife encounters are never guaranteed and never forced. Ocean Calling works only with vetted, ethical local operators, and every animal is free to approach, or not, entirely on its own terms.