Humpback whales are mysterious and graceful creatures. They’re most famous for their unusual yet beautiful dance-like breaching, where they launch themselves out of the sea and into the air. Scientists aren’t exactly sure why humpbacks breach, but they think it could be for hygiene, communication, and play. Another oddly beautiful behavior that humpbacks are well known for is even less understood: blowing bubbles.

It’s been established that humpbacks release large quantities of bubbles in rings out of their blowholes to corral schools of krill and small fish, which makes hunting the one to one-and-half tons of food they need to eat each day much easier. But researchers now think humpbacks’ bubble blowing may have other uses, too, first and foremost as an important form of communication. And it’s a form of communication that comes with a serious risk: drowning.

“Bubbles are a visual cue that’s especially effective in clear water,” says the whale researcher Joy Reidenberg, of the Icahn School of Medicine at Mount Sinai. “Since bubbles make less sound than a vocalization, whales may use them to send a signal without attracting the attention of predators.”

A Humpback whale creates bubble net to corral and catch prey. (Jodi Frediani)

While it seems certain that humpbacks are using bubbles to send some sort of messages to one another, what exactly the whales are saying is less clear, Reidenberg says. Bubbles could be used for emphasis or to convey emotion, “the equivalent of a grammatical exclamation point, a superlative word, or a hand or facial gesture,” she speculates. “Maybe it’s like slamming our fist on the table when we’re angry, or raising a middle finger.” Or bubbles could be a sign of distress.

Reidenberg adds that it’s also very possible whales use bubbles for a variety of purposes apart from communication. In place of solid objects, humpbacks might enjoy bubbles as toys, both for play and even sexual pleasure, she says. They might use them as boundary lines delineating mates or territory. And bubbles could work as camouflage, concealing whales from predators in a wall of opaque white foam.

Accounts from longtime whale watchers back up Reidenberg’s research. The California-based wildlife photographer Jodi Frediani says she’s seen bubbles used for non-feeding purposes come out of not only whales’ blowholes, but their mouths and genital slits. Frediani has observed female humpbacks rolling or twirling to create bubble trails with their flukes and fins. “This is quite fascinating to me, as the use appears to be a tactile, sensuous or sensual experience,” she says. “I, myself, have been above a blowhole-bubble exhalation, and it’s akin to what I imagine it would be like to be in a bath of champagne! Very tingling!”

Artie Kopelman, another longtime whale watcher, has also noticed non-hunting uses of bubbles in his humpback-whale encounters. In one instance last summer, he and a small group were drifting in a boat when suddenly a ring of bubbles surrounded them. “This might have been an agonistic display, or an attempt to build a wall around us,” says Kopelman, who’s the president of an ocean-education organization that gives whale-watching tours off Long Island.

But Kopelman emphasizes this was probably a rare incident and that the majority of his humpback-bubble observations have been for use as a hunting tool.

The primary danger of bubble blowing that whales face is drowning. Reidenberg and co-author Jeffrey Laitman published a study in 2007 that examined the respiratory systems of seven deceased humpback whales to try and better understand how humpbacks physiologically produce their famous “whale songs” and blow bubbles. They found that humpback whales are able to keep their respiratory and digestive tracts separate while exhaling bubbles through their blowholes to avoid water from entering their lungs. But when they emit bubbles from their mouths, whales’ windpipe connections to the nostrils are rerouted, so air in the windpipe travels into the mouth instead.

A Humpback whale creates stream of bubbles with its fluke. (Jodi Frediani)

“This allows overlapping of the breathing and swallowing pathways,” says Reidenberg. “This is risky behavior that could result in drowning if the water in the mouth accidentally flows into the windpipe.”

It’s already known that whales have developed physical adaptations that prevent them from drowning while singing. And Reidenberg and Laitman’s findings suggest that while there does seem to be a danger of drowning to bubble-blowing whales, that danger may be minimized by a valve-like arrangement of whales’ respiratory structures that prevents backflow of water into the lungs.

Whatever specific mechanism is at play, it seems that the benefits of bubble blowing outweigh the risks. “Trapping food is certainly essential for individual survival. Confusing a predator is also essential for individual survival. … Finding and defending a mate is essential for species survival. Using bubbles for play, entertainment, and stimulation is also essential for healthy social growth and bonding,” says Reidenberg. “One can argue that every use of bubbles is important.”