Humpback whales may not have hands, but that doesn’t mean they’re clumsy: A new study argues that the aquarium mammals should be classified as tool-using animals, thanks to their ability to use nets made from bubbles to catch krill.
The whale in question was discovered by researchers off the coast of Alaska in July 2019. Over a period of five days, the scientists filmed the whale building a bubble net, a widely observed behavior. Of particular interest was the actual composition of the net, its size, and the distance between the bubbles. Over the next two years, the researchers returned for further investigations and continued to measure the bubble nets. During that time, they recorded hundreds of bubble nets built by dozens of whales. All of the nets recorded contained multiple circular rings of bubbles that got smaller as the rings progressed.
In a paper published in the journal Royal Society Open ScienceAfter analyzing the data, the researchers found that the whales weren’t building their nets haphazardly. Rather, they manipulated the size and configuration of their nets in different ways, such as changing their depth or the spacing of the bubbles. The whales were able to achieve this by varying the rate at which they made bubbles while swimming at a constant speed.
The nets were used to create a barrier, confining schools of krill, fish, and other food to a small area where the whales could feed.
Although chasing prey into a small area might seem like it would require whales to expend less energy, the researchers concluded that this is not the case: humpback whales’ breathing rates were similar to those of whales that lunged at their prey without using nets, and the energy expended building nets was likely similar to that used by non-net-building whales while feeding.
Instead, they may have an advantage in that they can catch more prey in one bite: For every lunge made by a net-using whale, a non-net-using whale may make up to 15 lunges, the scientists said. Overall, they estimated that the prey density of the tool-using animals was seven times higher than that of their lunging cousins.
The researchers argued that this behavior met the definition of tool use, which is the intentional use of “an object detached from the environment” to modify, position or control another object or organism.
“Many animals use tools to find food, but few actually make or improve their own tools,” Lars Bader, director of the University of Hawaii’s Marine Mammal Research Program, said in a press release. “These whales expertly blow bubbles in patterns that form nets with internal rings, actively controlling details such as the number of rings, the size and depth of the net, and the spacing of the bubbles.”
Tool-making has been found in a wide variety of species, including mammals, birds, fish and insects, but it’s relatively rare among animals. It’s no wonder that future aliens would want to talk to humpback whales.
