Einstein Science Reporting for Kids
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American Association for the Advancement of Science

You won't hear this Nemo on American Idol

While the animated fish Nemo talks, real clownfish aren't ready to appear on the television show American Idol. The real Nemos (a.k.a. clownfish) only make "chirps" and "pops." Upon hearing it, Simon would say "that's ghastly."

Researchers recently learned how the clownfish communicates. Michael L. Fine is an oceanographer that worked on the project. "Lots of fish make sounds," he says. "Some make sounds by rubbing bones together and others use swimming muscles to make noise. Herring make noises by taking in air through the esophagus and blowing it out the anus in a rapid series using a process scientists call fast repeated ticking sounds, or FRTS."

The clownfish (Amphiprion clarkii) has adapted its feeding mechanism to produce sounds by percussive collisions of the teeth and vibration of the jaw. To learn this, scientists made sound recordings with high-speed video and X-rays to observe the movements accompanying the sound.

To make its "chirps" and "pops," sounds, which it does for mating and when it is in a dispute, the clownfish elevates its head, lowers the hyoid bar (it that supports the tongue), moves the pectoral girdle backwards and closes the lower jaws. The sound occurs when the hyoid bar is quickly lowered as the mouth closes simultaneously.

Oceanographers dissected a clownfish and learned that the ligament that is responsible for the rapid lower jaw movement acts like a drawbridge. It acts like a cord to force the mouth shut. The sound is caused by colliding jaw teeth and the jaws radiate the sound.

All of the 27 Amphiprion species seem to use at least a variation of this sound-making process.

This study appears in the 18 May issue of the journal Science.