Whale sonar. Artwork illustrating the sonar mechanism used by whales to detect their prey (such as squid, far right). Toothed whales, such as this Blainville's beaked whale, produce a variety of sounds by moving air between air-spaces or sinuses in the head. Sounds are reflected back from objects. These echoes are thought to be received by an oil-filled channel in the lower jaw, and conducted to the whale's middle ear. The waveform across bottom (white) shows the pulses of sonar (grey cone) sent out from the whale's head. The echoes are also shown returning from the squid, and show up on the waveform as the smaller peaks.