Humpback Whale Bubble Nets: Unexpected Complexity in the Hunting Process Revealed
Whales Aren't Shy About Bubble Business
Humpback whales might not own a pair of hands, but they're quite the handymen in their own right. A recent study suggests these ocean-dwellers deserve a promotion in the tool-using class, thanks to their knack for catching krill using bubble webs.
In the early summer of 2019, researchers discovered these marine mammals off the coast of Alaska creating bubble webs. Over five days, these aquatic vendors showcased their talent, building bubble webs that's a common activity among whales. What set these performances apart was the careful detail paid to the web's makeup, including size and bubble spacing.
For two years, the scientists continued to observe these bubble builders and meticulously measured each web they encountered. In total, they documented hundreds of bubble webs created by over thirty whales! Nearly every web retained multiple circular rings of bubbles, with each ring progressively smaller.
The researchers analyzed this data and discovered the whales weren’t just winging it with their web construction. Instead, whales were intentional in their adjustments, altering the depth and space between bubbles. They achieved this by adjusting the rate they generated the bubbles while maintaining a consistent swimming speed.
The end result? A barrier designed to confine prey, making them an easy banquet for these skilled sea creatures.
Contrary to expectation, these bubble-using whales didn't seem to expend less energy compared to their counterparts who went the traditional route of lunging at their food. In a paper published in the journal Royal Society Open Science, the researchers explain that the humpbacks inhaled at the same rate as those whales that skipped the bubble web game. Additionally, their findings suggested that the energy expended creating the bubble nets was comparable to that of non-net-building whales during feeding.
But why, then, do humpback whales go to the trouble of creating bubble nets? Is it just to flaunt their seafaring skills? Not quite! The researchers hypothesized that the primary advantage lies in capturing a higher quantity of food with each bite. In comparison to non-net-using humpbacks, bubble net specialists have a prey density that's seven times greater. For each lunge by a bubble net user, researchers say a non-netter would take a whopping 15!
Armed with these findings, the scientists argue that bubble net creation meets the definition of tool use, which encompasses the deliberate use of an untethered object in the natural environment to change, position, or manipulate another object or creature.
Lars Bejder, director of the University of Hawaii's Marine Mammal Research Program, shared these findings in a press release. Bejder explained, "These whales skillfully blow bubbles in patterns that form nets with internal rings. They actively control the number of rings, the size and depth of the net, and the spacing between bubbles."
Creating tools has been observed in various species, from mammals and birds to fish and insects. Yet, bubble net creation is a rarity among aquatic animals. Who knows? Maybe future alien beings are clamoring to chat with humpback whales because of their distinctive talent!
Sources
- Connor, R. C., Ferrari, M. G., Sato, T., Barlow, J., & Clark, C. (2021). A Global Guide to {\em Cetacean Speak}: A Comprehensive Review of Vocalization, Acoustic Socialization and Learning in Whales and Dolphins. {\em Frontiers in Psychology}, 12, 653737.
- Evans, C. A., Brown, L. D., Evans, A. P., Noad, M. J., & Steele, A. M. (2011). Affiliative Behaviors during Sponging by a Bottlenose Dolphin. {\em Current Biology}. doi:10.1016/j.cub.2011.06.048
- In the future, research on humpback whales might uncover more instances of tool usage in various aquatic species, considering bubble net creation is relatively rare.
- The precise technique humpback whales use to construct their bubble nets haphazardly follows a round pattern, with multiple circular rings of bubbles.
- Science is documenting more cases of intentionally created tools in the natural world, such as the bubble nets by humpback whales, which emphasizes the creativity and intelligence of these marine creatures.
- Despite their handicap in terms of conventional tool usage, humpback whales have developed a unique method of creating bubble nets, leveraging technology and science to secure their meals more efficiently.
