The idea of a seal clapping often conjures images of an animal trained for human entertainment in a zoo or aquarium. However, some wild seals perform a loud, forceful clap entirely of their own accord deep beneath the ocean surface. This behavior is not a trick learned for a reward, but a powerful form of acoustic communication that serves a distinct purpose in the animal’s complex social life. The discovery of this natural action provides scientists with new insight into how marine mammals interact and establish their dominance.
Identifying the Clapping Seals
The primary species documented using this unique form of non-vocal acoustic signaling is the wild grey seal, Halichoerus grypus. The first scientific confirmation and footage of this behavior came from observations of male grey seals off the coast of the Farne Islands in the United Kingdom. This specific population became the focus for researchers who had long suspected the existence of this sound based on anecdotal reports from divers. This intentional communication must be distinguished from the trained flipper-slapping often seen in captive sea lions or fur seals. The grey seal’s action involves forcefully bringing its two fore-flippers together underwater.
The Role of Clapping in Social Structure
The underwater clap is a clear, aggressive display used almost exclusively by male grey seals during the competitive breeding season. Scientists interpret the sound as a signal of strength and fitness, functioning as an underwater challenge to rivals. This action allows a dominant male to establish and maintain his territory without the energetic cost and risk of physical fighting. The clap is considered a form of honest signaling, meaning that only the strongest and most capable males can execute the action to generate a loud, effective sound.
When a male seal claps, the resulting noise acts as a warning to other males to keep their distance. If a male is particularly dominant, one or two loud claps are often sufficient to cause competitors to disperse immediately. The behavior carries a dual message, similar to a male gorilla beating its chest: it warns away competitors while simultaneously advertising the male’s superior genes to potential mates. The frequency and intensity of the clap are directly correlated with the seal’s social status.
How the Clap Translates Underwater Acoustics
The physical act of a seal clapping its fore-flippers together produces a loud, high-frequency sound described by observers as a “gunshot-like crack.” This powerful noise is created by the rapid, forceful collision of the two flippers, which generates a cavitation bubble that immediately collapses. The collapse of this bubble creates the sharp, percussive sound wave that travels through the water. The sound is much louder and clearer acoustically underwater than the visual action might suggest above the surface.
Sound travels approximately four times faster in water than in air, making acoustic signals an efficient way to communicate across distances in the marine environment. The high-frequency nature of the clap allows it to effectively cut through the lower-frequency background noise of the ocean. This clear, sharp signal ensures that the message of dominance or warning is transmitted to other seals even across longer ranges. The ability to produce such a forceful signal is a testament to the grey seal’s specialized anatomy, particularly its shorter, paw-like forelimbs.