'It shows the power of the matriarch': Heartbreaking footage shows orca mom and son team up to drown another pod's calf

Heartbreaking footage shows an orca mom and her adult son drowning a young calf from a neighboring pod. The dramatic video is likely the first time this rare behavior has been filmed. 

In the video, a female orca (Orcinus orca) and her daughters begin to play with the calf — a behavior that is not unusual when two pods come together. However, the play soon turns violent. The son hits the calf with force, then he and his mother trap the calf between them, forcing it underwater to drown it. 

The brutal clip was filmed as part of National Geographic's new series "Queens," which looks at the behaviors of matriarchs in the animal kingdom. 

Orca infanticide is extremely rare, and it wasn't something the production team was expecting to capture. "This behavior is so rare — in fact we think this is probably the first case of filmed orca infanticide," Chloe Sarosh, executive producer on the series, told Live Science. "We didn't plan to film it, it was just a case of right place, right time."

The team filmed the encounter over several hours, Sarosh said. A few days later, an orca that matched the size and description of the drowned calf washed up dead on a shore 5 miles (8 kilometers) away. It's assumed this was the same drowned calf.

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Because the encounter was so unexpected, the team contacted several scientists to help interpret the behavior and confirm it was a case of infanticide. While the behavior of the matriarch and her son is clear, understanding the reactions of the other pod members and their roles will require further analysis. "That's why this footage is so important because it gives scientists a chance to study it to identify fins and markings of who and what role they're playing in this behavior," Sarosh said.