When it comes to quirky animal behaviors, few are more charming than 2,000-pound beluga whales blowing delicate bubbles. But why do they do it? To find out, researchers spent eight years gathering data on 11,858 “bubbling events”—the most comprehensive study of this form of cetacean creativity.

From This Story The Genesis of Animal Play: Testing the Limits Buy

As they observed belugas at Marineland Park near Toronto, the biologist Michael Noonan and his students discovered a kind of bubble semantics. The whales often expelled big bursts of bubbles through their blowholes when they were startled. Pairs released bubble streams as they swam side by side—apparently in a spirit of companionship, unlike the aggression shown by bubbling humpback duos. The belugas also blew bubble rings, but apparently not when they had more serious things to do: Males rarely did it during the spring breeding season. “That’s when they’re busy patrolling the pool, cruising for females,” Noonan says. In summer, males again blew bubble rings, swatting to change their shapes and swimming through them as if they were hoops. “This is a species that makes its own toys,” says Noonan.

Whimsical behavior isn’t unique to belugas. Apes, dogs, birds, reptiles and even spiders play, according to a recent issue of the journal Current Biology devoted to the subject. But animal play usually takes the form of tugging, chasing or wrestling—activities that might help develop survival skills down the line. In contrast, a mammal has every reason not to exhale underwater. “When you’re a breath-holding animal,” says Noonan, “you can hardly think of anything more precious than air.”

One possible explanation is that the belugas are bored. In the wild, they cover vast distances and dive into deep trenches. At a marine park, they’re confined to concrete pools. “Captive animals are deprived of a lot of normal stimuli,” says Gordon Burghardt, a professor at the University of Tennessee and the author of The Genesis of Animal Play. “So you often see them engaging with their environments in ways they wouldn’t normally do.”

But Noonan, an expert on animal cognition at Canisius College in Buffalo, New York, thinks there’s more to it than that. He argues the whales might be blowing rings for much the same reason that people dance or draw: to engage with the world and express their innate curiosity about it. “We’re mammals and they’re mammals,” Noonan says. “That doesn’t mean their mental lives are identical to ours. But until proven otherwise, I think we can assume we are more similar than we are different.”