Seals are marine mammals known for their diverse vocalizations, producing a wide array of sounds both on land and underwater. These sounds vary significantly among different seal species, reflecting their unique environments and social structures. Exploring the different noises seals make and the reasons behind them offers insight into their complex communication behaviors.
Types of Seal Sounds
Seals exhibit a rich vocal repertoire. Common in-air vocalizations include barks, growls, grunts, moans, and honks, often heard in crowded rookeries or during interactions on land.
Some species, like the Weddell seal, produce complex underwater vocalizations that can include chirps, whistles, and trills. These underwater sounds can sometimes reach frequencies beyond human hearing, with Weddell seals producing ultrasonic calls up to 50 kHz. Other sounds like roars are characteristic of some species, with harbor seals using a distinct roar underwater.
Why Seals Vocalize
Seal vocalizations serve various communicative purposes within their social structures. One primary function is territorial defense, where male seals use calls to establish and protect their areas, particularly during breeding seasons. These vocal displays can be amplified underwater, traveling over long distances to signal presence to rivals.
Vocalizations are also important for attracting mates, with some male seals producing specific underwater calls to draw females. Mothers and pups use distinct vocalizations for identification and reunion, especially in crowded breeding colonies. Pups often vocalize more frequently than adults, and their cries can be individually distinctive to their mothers. Seals also use sounds to warn others of potential predators or to express aggression towards conspecifics.
How Seals Produce Sound
Seals produce sounds through physiological mechanisms involving their vocal cords and the controlled movement of air. Like many mammals, they generate sound by vibrating vocal folds within the larynx as air passes through. The length and geometry of the vocal tract, the air-filled passage above the vocal folds, then filter and shape these sounds. This process allows for a range of pitches and qualities in their vocalizations.
Some seal species possess specialized anatomical features, such as air sacs, which can influence sound production by modifying the vocal tract’s acoustic properties. These structures can also extend the dynamic range of vocalizations. While sound production on land involves air expulsion, seals are also capable of vocalizing underwater, sometimes with their mouths closed, which makes studying their vocal machinery challenging.