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How do toothed whales 'see' in the dark?

Although most mammals typically have good eyesight, cetaceans (whales) are an exception. Water is dense therefore light does not penetrate far beneath the surface.

All toothed whales, called Odontocetes, which include among others, dolphins, porpoises, pilot whales and Sperm Whales have developed the ability to 'see' with sound, by utilizing it as a kind of underwater 'acoustic flashlight'. Various species send out extremely powerful bursts of sounds like 'clicks', 'squeaks', 'whistles' and 'squeals'. The sound waves will move through the water until they encounter an object that is of greater density than water. Once the waves hit an object, the sound will bounce back in the form of an echo.

Sound appears to be produced in the fatty cushion of the melon, while incoming echoes seem to be received and conveyed through the lower jaw. When the echo is received, it is processed by the brain into information that allows the animal to 'see' its surroundings. This can include direction, speed, distance, shape, texture and density of objects.

Odontocetes have perfected the ability to navigate and hunt using sound.

Learn more in following Odyssey log:
'Seeing With Sound - Echolocation'
"To try and understand the perceptual world of cetaceans, it is necessary to imagine changing your primary sense from sight to sound. In this case, 'sound' images rather than 'visual' images are stored in the brain. Your sense of those around you, where you are and who you are with, are all determined by the sounds of others, or the sounds that you make."
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Listen to the Odyssey log:
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