Scientists found four distinct types of bubbles produced by beluga whales underwater.
Blowhole drips and mouth rings, they discovered, suggest a playful mood. These bubbles are used more by females than males.
Blowhole bursts occur when a beluga feels startled or surprised. This kind of bubble was used mostly by adult females, who scientists concluded were more reactive than adult males.
Blowhole streams, used more by males, could suggest aggression, but scientists also saw male belugas using blowhole streams playfully, like when they were nicely swimming side by side.
It's a sad paradox that this study, which reveals the emotional complexity of beluga whales, depended on data from whales kept in tanks at Marineland in Niagara Falls, Canada.
Some days, the captive belugas used for the study didn't blow any bubbles at all.