A team of scientists from the SETI Institute and the University of California at Davis has documented, for the first time, humpback whales producing large bubble rings, like a human smoker blowing smoke rings, during friendly interactions with humans. This previously little-studied behavior may represent play or communication.

The paper is published in the journal Marine Mammal Science.

Humpback whales are already known for using bubbles to corral prey and creating bubble trails and bursts when competing to escort a female whale. These new observations show humpback whales producing bubble rings during friendly encounters with humans. This finding contributes to the WhaleSETI team’s broader goal of studying non-human intelligence to aid in the search for extraterrestrial intelligence.

“Because of current limitations on technology, an important assumption of the search for extraterrestrial intelligence is that extraterrestrial intelligence and life will be interested in making contact and so target human receivers,” said Dr. Laurance Doyle, SETI Institute scientist and co-author of the paper. “This important assumption is certainly supported by the independent evolution of curious behavior in humpback whales.”

“Humpback whales live in complex societies, are acoustically diverse, use bubble tools and assist other species being harassed by predators,” said co-lead author Dr. Fred Sharpe, UC Davis Affiliate. “Now, akin to a candidate signal, we show they are blowing bubble rings in our direction in an apparent attempt to playfully interact, observe our response, and/or engage in some form of communication.”

“Humpback whales often exhibit inquisitive, friendly behavior towards boats and human swimmers,” added co-lead author Jodi Frediani, marine wildlife photographer and U.C. Davis Affiliate. “We’ve now located a dozen whales from populations around the world, the majority of which have voluntarily approached boats and swimmers blowing bubble rings during these episodes of curious behavior.”

The study analyzes 12 bubble ring–production episodes involving 39 rings made by 11 individual whales.

Similar to studying Antarctica or other terrestrial analogs as a proxy for Mars, the Whale-SETI team is studying intelligent, non-terrestrial (aquatic), nonhuman communication systems to develop filters that aid in parsing cosmic signals for signs of extraterrestrial life. As noted by Karen Pryor, “patterns of bubble production in cetaceans constitute a mode of communication not available to terrestrial mammals” (Pryor 1990).

The team had previously published a paper on humpback whale communication in PeerJ.