Even though these huge fish are 12 feet across, the social behavior of the reef manta ray has generally remained secretive—until now.

In rare drone footage captured off the coast of Oahu in Hawaii by Mark Merkley, the unique and graceful feeding behavior of the reef manta ray is captured in great detail.

“When drone technology came out we noticed that mantas were behaving a lot more naturally without boats around,” says Andrea Marshall, the Director of the Marine Megafauna Foundation and a National Geographic explorer. She was not involved with capturing this video but has been researching the behavior of mantas for over 15 years. (Read about how to stick a camera on a manta ray.)

Marshall explains that this circling behavior is a social way of eating. Manta ray individuals “stack” behind one another while feeding. The one in front gets the most plankton via filter feeding with its giant gaping mouth, but they switch places as they swim so each gets a turn in the leader position.

“They seem to associate closely with one another. When they spend time together, they are incredibly social,” says Marshall, who adds that these animals don’t just feed together, but they also play together. (How to Give a Manta Ray a Makeover.)

The social groupings of manta rays are intriguing in part because they aren’t necessarily family groups. In her own research, Marshall is analyzing their DNA to see if they are related in an attempt to understand why these animals spend so much time together—but they might just be friends that grew up together.