Newcastle University researcher Ben Burville captured a wild grey seal "clapping" on camera for the first time. Previously, researchers believed the noise to be a vocal sound, similar to the calls and whistles that other marine mammals produce. But the video provides evidence that wild grey seals produce the sound, which sounds like a loud "gunshot-like crack", with their flippers and to ward off competing seals during mating season. The clap of the flippers creates a high-frequency noise that cuts through background sounds. This allows each slam to send clear signals to other seals.