Humpback whales may not have hands, but that doesn’t mean they aren’t handy. A new study argues the aquarian mammals should be classified as tool users, thanks to their ability to catch krill using nets made of bubbles.

For the next two years, the researchers returned for more expeditions and kept measuring the bubble nets. They ended up documenting hundreds of bubble nets over that time, created by dozens of individual whales. All the documented nets contained multiple circular rings of bubbles, with each successive ring smaller than the last.

They analyzed that data, and found the whales weren’t creating the nets haphazardly. Rather, the whales were manipulating the size and makeup of the nets in several ways, including altering their depth, and the space between bubbles. The whales were able to accomplish this by changing the rate at which they made the bubbles, while still swimming at a constant speed.

The nets created barriers that were used to corral krill, schools of fish, and other food into a small area where the whales could then feast.

The researchers argued that this behavior meets the definition of tool use, which they say is the purposeful use of an “unattached environmental object” to alter, position, or otherwise control another object or organism.

Tool crafting has been found in an assortment of species, including mammals, birds, fish, and insects, but it’s relatively rare among animals. No wonder future aliens are so desperate to talk to humpback whales.