How humpback whales use bubbles as a tool
A new study confirms a theory that humpbacks are a tool-using species, as they deploy nets of bubbles to catch fish and krill.
Humpback whales (like these in the coastal waters of the Antarctic Peninsula) have long been observed creating rings of bubbles to corral prey.
Photograph By Whale Research Solutions
Chimpanzees use sticks to fish for termites, sea otters crack open clams with a rock and dolphins use sea sponges on their noses for protection while foraging on the ocean floor. A new study adds humpback whales to the list of non-human species that use tools. Humpbacks may not only use a tool, but create it from their environment by blowing bubbles.
Around the world, humpback whales (Megaptera novaeangliae) use bubble-nets to trap certain prey such as krill, herring, and young salmon, sometimes in coordinated groups and at times alone. The whales dive down below their prey and swim in circles while releasing bubbles from their blowholes to create a rising curtain. The curtain creates a visual barrier that tricks the prey into thinking there’s no escape. Once the prey is tightly corralled, the whales lunge through the bubble-net with open mouths to swallow their meal. This feeding behavior has been observed for decades, but the precise mechanics behind it are difficult to study and have long remained a mystery.
While watching humpbacks feeding “it looks like a big scattering of bubbles and it doesn't look like it's very structured,” says Andrew Szabo, a marine ecologist who leads the Alaska Whale Foundation and an author on the study. But that all changes when you add drones and underwater cameras, he says.
While tool-use in animals can sometimes be challenging to define, scientists now tend to think about describing tool use as using an external object that isn’t attached to anything to change the shape, position, or condition of something else. It’s been suggested before that bubble-netting is using a tool, but “this paper strengthens that position,” says Janet Mann, a marine mammal biologist at Georgetown University in Washington D.C. who has studied aquatic tool-use extensively.
Humpback whales sometimes work in teams to hunt prey like herring using disorienting curtains of bubbles.
Photograph By Brian Skerry
Feeding frenzy
To get a better look at the behavior, Szabo and the team used 20-foot poles to attach specialized underwater suction tags on whales in northern Southeast Alaskan waters. These tags, equipped with 4K video cameras, hydrophones and sensors to record movement in three dimensions, as well as temperature and depth, collected data for up to 24 hours before detaching. The scientists combined the tag data with aerial footage captured by drones to precisely measure the timing, structure, and size of the bubble nets made by solitary whales.
And it turns out that these gentle giants adjust the speed and spacing of their bubble emissions to trap prey more effectively, the researchers report August 21 in Proceedings of the Royal Society Open Science. By altering the bubble rings, the whales may be able to catch seven times the prey on average in just one gulp. The whales are conserving energy, having to lunge fewer times, says Szabo, who is also a National Geographic Explorer. This efficiency is crucial for humpbacks, as they migrate thousands of miles and need to capture enough food during the summer and fall in Alaska to sustain themselves throughout the year.
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“They have so much control over how they're doing this,” says Lars Bejder, another author a the study and marine mammal biologist who directs the University of Hawai’i at Manoa’s Marine Mammal Research Program. “They are increasing the frequency of the pulses as the net gets smaller, to lessen the mesh size of how the prey can escape. And that's really cool.”
For the team, humpbacks’ ability to use bubble-nets as tools speaks to the whales’ cognition and complexity, which is often overshadowed by other marine mammals, like dolphins, Szabo says. “They are remarkable animals, doing remarkable things.”
A new study confirms a theory that humpbacks are a tool-using species, as they deploy nets of bubbles to catch fish and krill.
Humpback whales (like these in the coastal waters of the Antarctic Peninsula) have long been observed creating rings of bubbles to corral prey.
Photograph By Whale Research Solutions
Chimpanzees use sticks to fish for termites, sea otters crack open clams with a rock and dolphins use sea sponges on their noses for protection while foraging on the ocean floor. A new study adds humpback whales to the list of non-human species that use tools. Humpbacks may not only use a tool, but create it from their environment by blowing bubbles.
Around the world, humpback whales (Megaptera novaeangliae) use bubble-nets to trap certain prey such as krill, herring, and young salmon, sometimes in coordinated groups and at times alone. The whales dive down below their prey and swim in circles while releasing bubbles from their blowholes to create a rising curtain. The curtain creates a visual barrier that tricks the prey into thinking there’s no escape. Once the prey is tightly corralled, the whales lunge through the bubble-net with open mouths to swallow their meal. This feeding behavior has been observed for decades, but the precise mechanics behind it are difficult to study and have long remained a mystery.
While watching humpbacks feeding “it looks like a big scattering of bubbles and it doesn't look like it's very structured,” says Andrew Szabo, a marine ecologist who leads the Alaska Whale Foundation and an author on the study. But that all changes when you add drones and underwater cameras, he says.
While tool-use in animals can sometimes be challenging to define, scientists now tend to think about describing tool use as using an external object that isn’t attached to anything to change the shape, position, or condition of something else. It’s been suggested before that bubble-netting is using a tool, but “this paper strengthens that position,” says Janet Mann, a marine mammal biologist at Georgetown University in Washington D.C. who has studied aquatic tool-use extensively.
Humpback whales sometimes work in teams to hunt prey like herring using disorienting curtains of bubbles.
Photograph By Brian Skerry
Feeding frenzy
To get a better look at the behavior, Szabo and the team used 20-foot poles to attach specialized underwater suction tags on whales in northern Southeast Alaskan waters. These tags, equipped with 4K video cameras, hydrophones and sensors to record movement in three dimensions, as well as temperature and depth, collected data for up to 24 hours before detaching. The scientists combined the tag data with aerial footage captured by drones to precisely measure the timing, structure, and size of the bubble nets made by solitary whales.
And it turns out that these gentle giants adjust the speed and spacing of their bubble emissions to trap prey more effectively, the researchers report August 21 in Proceedings of the Royal Society Open Science. By altering the bubble rings, the whales may be able to catch seven times the prey on average in just one gulp. The whales are conserving energy, having to lunge fewer times, says Szabo, who is also a National Geographic Explorer. This efficiency is crucial for humpbacks, as they migrate thousands of miles and need to capture enough food during the summer and fall in Alaska to sustain themselves throughout the year.
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For as little as $2/mo.
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“They have so much control over how they're doing this,” says Lars Bejder, another author a the study and marine mammal biologist who directs the University of Hawai’i at Manoa’s Marine Mammal Research Program. “They are increasing the frequency of the pulses as the net gets smaller, to lessen the mesh size of how the prey can escape. And that's really cool.”
For the team, humpbacks’ ability to use bubble-nets as tools speaks to the whales’ cognition and complexity, which is often overshadowed by other marine mammals, like dolphins, Szabo says. “They are remarkable animals, doing remarkable things.”
