Humpback whales (Megaptera novaeangliae) manufacture bubble-nets as tools to increase prey intake

NEWS - Humpback whales (Megaptera novaeangliae) create bubble net tools while foraging, consisting of internal tangential rings, and actively control the number of rings, their size, depth and horizontal spacing between the surrounding bubbles. These structural elements of the net increase prey intake sevenfold.

Researchers have known that humpback whales create “bubble nets” for hunting, but the new report shows that the animals also manipulate them in a variety of ways to maximize catches. The behavior places humpbacks among the rare animals that make and use their own tools.

“Many animals use tools to help them find food, but very few actually make or modify these tools themselves,” said Lars Bejder, director of the Marine Mammal Research Program (MMRP), University of Hawaii at Manoa.

“Humpback whales in southeast Alaska create elaborate bubble nets to catch krill. They skillfully blow bubbles in patterns that form a web with internal rings. They actively control details such as the number of rings, size, depth and spacing between the bubbles,” Bejder said.

This method allows them to catch up to seven times more prey in each dive without using any extra energy. This impressive behaviour places humpback whales among a rare group of animals that make and use their own tools to hunt.

Humpback whales (Megaptera novaeangliae) manufacture bubble-nets as tools to increase prey intake 2

Marine mammals known as cetaceans, including whales, dolphins and porpoises, are notoriously difficult to study. Bejder and his team used special tags and drones to study the whales’ movements above and below the water. The sophisticated new tools in the hands of researchers are making it possible to discover even more fascinating cetacean behaviour.

“We attached non-invasive suction tags and flew drones above humpback whales in bubble nets, collecting data on their movements underwater. It takes skill and precision to tag and track with drones,” said William Gough of the MMRP.

Cetaceans worldwide face a range of threats from habitat degradation, climate change, fishing, chemical pollution and noise. A quarter of the 92 cetacean species are threatened with extinction. There is a clear and urgent need for effective conservation strategies. Understanding this important behaviour could help to preserve the feeding grounds that sustain them.

Original research

Szabo A., Bejder L., Warick H., van Aswegen M., Friedlaender A. S., Goldbogen J., Kendall-Bar J. M., Leunissen E. M., Angot M. and Gough W. T. (2024). Solitary humpback whales manufacture bubble-nets as tools to increase prey intake. Royal Society Open Science, 11240328 DOI:10.1098/rsos.240328

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