It’s hard to miss: A 30-ton mammal flings itself out of choppy waters, hanging in the air for a brief moment before its 45-foot frame crashes back into the water, sending a plume of sea foam into the air as it lands.
You’ve just seen a humpback whale breaching. These whales have been spotted breaching—or exposing large portions of their bodies above the water—year-round, in their winter breeding grounds, their summer feeding grounds, and while traveling between the two. Their breaching behavior while on the move caught the attention of a team of scientists in Australia, who wondered why—when breaching takes so much energy, and humpbacks rarely, if ever, eat while migrating—these giants would use their energy to jump unless it meant something.
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Researchers working with the BRAHSS (Behavioural Response of Australian Humpback Whales to Seismic Surveys) project observed 94 different groups of humpback whales migrating past the coast of Australia en route to the Antarctic. In a scholarly article published in Marine Mammal Science, the team pinpointed specific surface behaviors—its term for the whales’ actions as they breach or slap the water with their fins—and what they might mean. It noticed the whales’ surface behaviors became more common on windy days or when there were other groups of whales very far away, supporting the opinion that whales use these behaviors as a form of communication. By leaping into the air or slapping the water with their fins, whales make major noise—noise that helps them communicate across large distances when background sounds from the weather, boats in the area, or other sources might block out their vocal noises.
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The team concluded that these surface behaviors serve multiple communication purposes for migrating humpback whales, purposes that can’t be achieved by vocal sounds. It also tried to decipher what the whales are trying to say. According to the article, breaching is possibly communication between far-apart groups of whales. Whales use the incredible underwater noise they can create by crashing their bodies into the water as a signal to other groups in the area, while fluke (tail fin) or pectoral fin slapping may be important for close-range and between-group communication. The whales may use this communication to mediate social interactions such as groups coming together or splitting apart.
Humpback whales breach and display surface behaviors year-round, so, even though migrating whales were the focus of this study, it's possible that they use these actions for the same purposes wherever they are. These actions take place regardless of the presence of an opposite-sex pairing and outside breeding grounds, so it's unlikely that they are limited to mating behaviors. This Australian team only studied humpback whales, but all species of whales breach, and it's possible that other baleen whales (like blue whales) use breaching to communicate, too.
The next time you’re fortunate enough to see a whale jumping above the water, know that jump takes a lot of energy, and it’s not just for fun or to put on a show—that jump might carry a message.