Ross Seal

The Ross seal is able to produce a variety of complex twittering and siren-like sounds that are performed on ice and underwater, where they carry for long distances.[4] The underwater siren sound can be composed of two harmonically unrelated superimposed tones that are pulsed with the same rhythm. Uniquely, the vocalizations, whether on ice or in water, are made with a closed mouth - emitting no air. The purpose of these sounds is unknown, though their distinctive nature and long range are likely to facilitate either encounters or avoidance of individuals.