Humpback whales caught blowing giant bubble rings underwater may have been attempting some kind of communication with their audience of human onlookers, a new study suggests.
Humpback whales (Megaptera novaeangliae) are known for blowing spiral bubble nets to hunt with, but not all bubbles have the same meaning in the world of whales. Some are intended to be playful; some frisky; and others are downright aggressive.
The particular genre of bubble-blowing documented in the report took the form of perfect circles, similar to ones described by biologist Roger Payne as "madly spinning doughnut-shaped clouds that look like giant smoke rings about three feet in diameter that rise rapidly to the surface."
An international team of biologists and photographers reviewed videos and photos of whales producing bubble rings, taken from below the water by a swimmer or overboard from a boat, and above the surface either from a boat, a plane, or a drone.
This variety of sources adds to the context in which the whales produce their rings, particularly important if we want to know whether they're meant as communication with humans or not.
Their data included a dozen separate examples of rings being made by the whales, equalling a total of 39 bubble rings generated by 11 different humpback whales.
"Out of the 12 episodes of ring production reported here, ten episodes were collected near a boat or human swimmers, while six episodes had more than one whale present," the researchers report.
"Despite these ample opportunities for intra- and interspecies aggression, there was no evidence of agonism toward conspecifics or aggression toward boats or swimmers in any of the ring episodes."
Quite the contrary, in fact. Far from showing signs of avoiding humans, eight of nine ring blowers approached the boat or swimmers, with exceptions to when they were blowing bubbles while feeding.
Whales of many different species have been observed exhaling near research and tourist vessels, exhibiting playful and friendly behavior. Intentionally blowing bubbles may be one more sign of wilful interaction, much as we might engage with other animals in whimsical acts of fun.
While these facts support the fantastic notion of whale-to-human communication, we're going to need a lot more data before we can be sure of the true meaning of these effervescent messages – and whether they're really intended for us at all.
"Whatever the reason for their creation, maintaining vigilance in the field will help elucidate the frequency and function of bubble rings," the researchers write.
"Both playful and communicative overtures of bubble rings may hold deeper meaning for humpback whales and their potential for interspecies communication."
The research is published in Marine Mammal Science.