Underwater in the Atlantic, you may hear puzzling noises that sound like underwater gun-shots. Thanks to a very patient naturalist and underwater video technology, the origin of the percussive sound has finally been documented! Male gray seals (Halichoerus grypus) rapidly ‘clap’ their front flippers together underwater, in what researchers think is an underwater communication signal to other seals. This rarely-seen clap behavior signals information about male breeding ability to potential mates or serve as a warning sign to other male competitors. 

Sketch and fact contributed by Karli Chudeau

Source: Hocking, D.P., Burville, B., Parker, W., Evans, A.R., Park, T. and Marx, F.G., 2020. Percussive underwater signaling in wild gray seals. Marine Mammal Science, 36(2), pp.728-732.