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Many years ago, the U.S. Navy came up with a way to spy on ships and submarines from other countries. They put microphones on the bottom of the Atlantic and Pacific oceans. The microphones pick up noises in the water. Radio waves carry the noises to land. There, experts listen to the sounds. They try to figure out what kinds of ships are in the water.
But the Navy noticed that not all of the noises were made by ships or submarines. Many were made by whales and other sea creatures! When whales are underwater, they make noises to talk to each other. Each kind of whales make a different noise.
Now, scientists are using the microphones to study whale noises. They are listening to the noises to try to count how many whales are in the oceans. That will tell them which kinds of whales are in trouble.
Atlantic -- the name of an ocean
count -- to check over one by one
creature -- an animal
microphone -- an instrument capable of transforming sound waves into electric current.
navy -- sea army
spy -- a person who keeps secret watch on the action of others
submarine -- a kind of warship that can navigate under water
whale -- an sea animal