Humpback whales (Megaptera novaeangliae) create the so-called ‘bubble-net tools’ to hunt, but researchers from the University of Hawai’i and the Alaska Whale Foundation have learned that these marine animals don’t just create the bubble-nets; they manipulate this unique tool in a variety of ways to maximize their food intake in Alaskan feeding grounds. This novel research demystifies a behavior key to the whales’ survival and offers a compelling case for including humpbacks among the rare animals that manufacture and wield their own tools.
Several animal species use tools for foraging; however, very few manufacture and/or modify those tools. Humpback whales, which manufacture bubble-net tools while foraging, are among these rare species. Using animal-borne tag and unoccupied aerial system technologies, Szabo et al. examine bubble-nets manufactured by solitary humpback whales (Megaptera novaeangliae) in Southeast Alaska while feeding on krill. They demonstrate that the nets consist of internally tangential rings and suggest that whales actively control the number of rings in a net, net size and depth and the horizontal spacing between neighboring bubbles. They argue that whales regulate these net structural elements to increase per-lunge prey intake by, on average, sevenfold. Image credit: Szabo et al., doi: 10.1098/rsos.240328.
“Many animals use tools to help them find food, but very few actually create or modify these tools themselves,” said University of Hawai’i Professor Lars Bejder.
“We discovered that solitary humpback whales in SE Alaska craft complex bubble nets to catch krill.”
“These whales skillfully blow bubbles in patterns that form nets with internal rings, actively controlling details like the number of rings, the size and depth of the net, and the spacing between bubbles.”
“This method lets them capture up to seven times more prey in a single feeding dive without using extra energy.”
“This impressive behavior places humpback whales among the rare group of animals that both make and use their own tools for hunting.”
Marine mammals known as cetaceans include whales, dolphins, and porpoises, and they are notoriously difficult to study.
Advances in research tools are making it easier to track and understand their behavior, and in this instance, Professor Bejder and colleagues employed specialty tags and drones to study the whales’ movements from above and below the water.
“We deployed non-invasive suction-cup tags on whales and flew drones over solitary bubble-netting humpback whales in SE Alaska, collecting data on their underwater movements,” said Dr. William Gough, also from the University of Hawai’i.
“The tools have incredible capability, but honing them takes practice.”
“Whales are a difficult group to study, requiring skill and precision to successfully tag and/or drone them.”
“This little-studied foraging behavior is wholly unique to humpback whales.”
“It’s so incredible to see these animals in their natural habitat, performing behaviors that only a few people ever get to see.”
“And it’s rewarding to be able to come back to the lab, dive into the data, and learn about what they’re doing underwater once they disappear from view.”
A paper describing this research was published in the journal Royal Society Open Science.
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A. Szabo et al. 2024. Solitary humpback whales manufacture bubble-nets as tools to increase prey intake. R. Soc. Open Sci 11 (8): 240328; doi: 10.1098/rsos.240328
This article is based on a press-release provided by the University of Hawai’i.
Source : Breaking Science News