LONDON - New footage shows for the first time that seals clap underwater to ward off competitors and show off to potential mates.

The action was captured on film for the first time by Dr. Ben Burville, a Visiting Researcher with Newcastle University, U.K. While it is not so unusual to see trained seals clap in a zoo or aquarium, the action had not previously been recorded in the wild and underwater.

Burville’s clip, described in the journal Marine Mammal Science, shows a male gray seal clap two times underwater in front of another male, creating a “cracking” noise.

Gray seals are gregarious and social creatures. Verbal signals (growls, hisses, hoots and caterwauls, etcetera) are often used by individuals to navigate group situations, while nonverbal signals such as flipper slaps and breaches play a role but were thought to be limited to the surface of the water.

After 17 years of trips to capture this very motion on camera, Burville filmed the underwater clapping on October 17, 2017 near the Farne Islands in northeast England. Burville witnessed similar behavior on five separate occasions and has heard it more than 20 times within a 20-year period.

The clap itself lasts for a fraction of a second (<0.1 seconds) and makes a high-frequency sound (>10 kHz), similar to a cymbal. The tone cuts through background noise, say researchers, to deliver a clear message to passing seals.

Based on researchers’ observations, the claps are performed by males and appear to be directed at others in the vicinity. The claps typically appear in bursts of one or two.

The study’s authors “tentatively” identify the clapping as male behavior, performed to deter competition from other males and attract females by displaying their strength.

“Depending on the context, the claps may help to ward off competitors and/or attract potential mates,” lead author Dr David Hocking from Monash University’s School of Biological Sciences said in a statement.