Seeing with Sound
Sending sound waves beneath the surface of the
Sonar, short for Sound Navigation and Ranging,
is helpful for exploring and mapping the ocean
because sound waves travel farther in the water
than do radar and light waves. Mapping the bottom
of the sea gives scientists an accurate picture with
to help keep mariners safe. However, since sea
creatures also use sonar, this noise is harmful to
sea animals.
Whales, dolphins and porpoises all use sonar to
and dolphins (for example killer whales and
bottle-nose dolphins) use echolocation for hunting
and navigating, while baleen whales (for example
humpbacks and blue whales) generally produce
a series of sounds which are frequently termed
‘songs’ that are used for communicating.
Echolocation is extremely sensitive and some
scientists think it may provide toothed whales
and dolphins with a three dimensional view of
the world. The whistles, clicks, groans and other
noises made by many toothed whales are also
thought to be also important in communication
between individuals.
Dolphins generate the high-frequency pulses
by squeezing air through nasal passages located
beneath their blowholes. They then focus on
forehead known as the melon. The melon focuses
its sound waves like lenses converge waves of
light. These focused sound waves are used to
the dolphin’s lower jaw and forehead. These areas
the sound waves towards the ears. They transform
it into signals which are sent to the brain for
interpretation.
Whalers used sonar to help catch whales.
They noticed that a by sending out mid-range
frequencies, they could not only locate whales but
easily harpoon them. Whales would react to the
sonar by blowing bubbles and surfacing in distress
making them an easy target.
species became stranded and died along North
Navy sonar training. Other sad examples around
the coast of the U.S. and elsewhere abound,
notably in recent years with more sonar testing
going on than ever before. According to the
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