Sound is used by several marine animals to different purposes, for example communication, navigation and predation. Given the scope of the question we will consider communication (dolphins) and navigation (sperm whales). 1) Communication: dolphins they emit different sounds with the air passing through their lips organs. This sound is received and assimilated by their conespecifics so they can orchestrate and synchronize different predation strategies or interact among themselves. 2) Navigation: sperm whales predate in the abysal waters, where there is not light. In such circumstances they emit sounds, which bounce once they reach something (somehow similar to the bats radar). The type of bouncing is organism/thing-specific, the sperm whale is able to retake the sound bouncing and adjust its trajectory if the bouncing profile is of its interest.