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
