Nature can be brutal. But animals also help each other, sometimes in ways unimaginable to the human observers. For instance, take the case of killer whales and dolphins, two top marine predators. According to new research, these mammals appear to have forged a special relationship—which scientists caught on camera for the first time.

In a Scientific Reports study published on December 11, researchers describe how killer whales, or orcas, collaborate with Pacific white-sided dolphins to track and feast on salmon off the coasts of British Columbia, Canada. The partnership was far more sophisticated than the two species sharing a meal, the paper reported, as the tag team capitalized on the other’s natural strengths.

For example, orcas used dolphin echolocation cues to locate large salmon, which are typically “prey that dolphins cannot capture and swallow whole,” the researchers explained in a statement. Once caught, the orcas broke down the salmon into smaller pieces to share amongst themselves, giving dolphins the leftovers.

Pesky dolphins?

As with many of the best scientific discoveries, the researchers stumbled upon this partnership accidentally. The researchers initially hoped to investigate how and why the orca populations of northern Canada were thriving compared to their southern counterparts. But their work encountered an unexpected obstacle: dolphins everywhere.

Pacific white-sided dolphin. Credit: University of British Columbia (A. Trites)/Dalhousie University (S. Fortune)/Hakai Institute (K. Holmes)/Leibniz Institute for Zoo and Wildlife Research (X. Cheng)

“At first you’re like, ‘Oh, get out of here. We’re trying to do some research,’” Keith Holmes, study co-author and a geographer at Hakai Institute, recalled to CBC, admitting at some point getting “a little annoyed.”

But that soon changed once the researchers had a closer look. If anything, the orcas were following the dolphins, not the other way around. Using drones and suction-cup biologging tags, the team was able to get aerial and underwater footage of what was happening.

Drone operator Keith Holmes (Hakai Institute) with researcher Taryn Scarff. Credit: University of British Columbia (A. Trites)/Dalhousie University (S. Fortune)/Hakai Institute (K. Holmes)/Leibniz Institute for Zoo and Wildlife Research (X. Cheng)

For roughly two years, the team recorded 258 unique events of dolphins traveling near tagged orcas. As the researchers reviewed the clips, they were mesmerized by what they saw.

Listen, catch, eat

The orcas were “sort of spread out and pinging through the water in a much broader area than what the whales can search—and the whale was listening,” Andrew Trites, study senior author and a marine biologist at the University of British Columbia in Canada, told CBC.

When the orcas read signs of large Chinook salmon in the vicinity, they quickly swam forward to deliver the killing bite, then shared the catch with their fellow orcas. After they were done, the dolphins arrived to feast on the leftover flesh and tissue.

There were no signs of any aggression during the whole process, Trites explained, although the killer whales could easily kill a dolphin if they wished to. “By working together, killer whales can conserve energy and use the dolphins as radar-equipped scouts to increase their chances of finding large Chinook salmon at deeper depths,” he added in the university statement.

Two killer whales tagged by the researchers. The tags eventually pop off and are harmless to the whales. Credit: University of British Columbia (A. Trites)/Dalhousie University (S. Fortune)/Hakai Institute (K. Holmes)/Leibniz Institute for Zoo and Wildlife Research (X. Cheng)

The dolphins get predator protection and consistent access to “one of the ocean’s most prized fish,” Trites said. “It’s a win-win for everyone involved.”

Collaboration or exploitation?

That said, there could be other ways to interpret this situation, Janet Mann, a behavioral ecologist at Georgetown University uninvolved in the new research, told Scientific American. For instance, it could just be that the killer whales are exploiting the dolphins’ tracking abilities to find salmon, she said.

Killer whales are among the top predators of the ocean ecosystem. Credit: University of British Columbia (A. Trites)/Dalhousie University (S. Fortune)/Hakai Institute (K. Holmes)/Leibniz Institute for Zoo and Wildlife Research (X. Cheng)

“I don’t think it’s been shown as cooperation because I think the standards for cooperation are a little bit higher,” Mann added. “It’s not like the dolphins wait for the killer whales to come and then they say, ‘Let’s go.’”

The researchers appear to be aware of this caveat, as in concluding the paper, they note that the extent to which this is a mutually beneficial relationship would require further studies. Additionally, it remains unclear whether this partnership subsists year-round or is limited to when there are high-value prey like the Chinook salmon nearby.

“This is just another piece of evidence of what kind of intricacies are happening out there,” Trites said.

Now, before you point out a certain something in the comments—yes, this is technically a dolphin-dolphin collaboration. Orcas (Orcinus orca) belong to the oceanic dolphin family Delphinidae, as do Pacific white-sided dolphins. And yes, orcas are dolphins—but they also qualify as whales. Toothed whales, to be precise.