Sounding Off

Echoes in the water
                 Dolphins can find food, enemies and other dolphins by sending out sound waves through the water.  This is called echolocation (EK-oh-low-KAY-shun).  It is the same type of system bats use.
                 Dolphins send out high-pitched sound waves through the water.When the waves reach an object, they bounce back to the dolphin. 
                 The echoes return to the dolphin's special jawbone.  The jawbone conducts the sound waves to the ear. 
                Dolphins can learn to tell how far away something is and what it is.  They can even learn what kind of fish makes what patternof sound waves.
Communication
                Dolphins communicate with each other with clicks, squeaks, grunts and whistles.  Sound waves travel more than four times faster throughwater than through air, at almost 1 mile per second.  So dolphins have no trouble "talking" to each other.
                Each dolphin has its own special whistle that other dolphins can recognize.
Whistling to the calves
                After a dolphin calf is born, the mother may whistle to it constantly for days.  This helps the calf learn its mom's special whistle. The calf may develop its ownwhistle by the time it is a month old.