You might think there’s no safer place underwater than snugged to the side of the largest fish on Earth. But you would be wrong.

Divers watched in awe as a particularly persistent bird called a cormorant dove below the waves and ripped off suckerfish that were stuck to a whale shark. The video was shot in 2011 by the Manta Scuba Diving company but recently resurfaced on Facebook.

“I’ve been working on whale sharks for 25 years, and I’ve never seen that before,” says Brad Norman, a National Geographic Explorer and one of the world’s foremost experts on whale sharks.

“And I’ve been swimming with whale sharks thousands of times. Literally thousands of times.”

Remoras, or suckerfish, make a living by following