Freaked Out Fish Grind Their Teeth and Produce Odd Noise

When in distress, a fish called the French grunt produces a jarring sound akin to fingernails-on-a-blackboard, and now a new study reveals how and why the fish do it.

The sound isn’t grunting at all — it’s produced by the fish grinding their teeth. The research, published in The Journal of Experimental Biology, demonstrates how this fish (Haemulon flavolineatum) can audibly communicate with others without a voice box.

The clever fish makes the most of its limited sound-producing anatomy.

“Sound production is probably an adaptation of the food-processing mechanism in this species,” lead author Frédéric Bertucci and colleagues from the Universities of Liège and Antwerp wrote.

The researchers recorded the calls, which are produced when the fish feels threatened. You can hear one of the fish making the sound as a fisherman grasps it.

Bertucci and his team tested French grunts’ hearing and examined high-speed X-ray movies of their heads.

All of this determined that the sound has a pitch of about 700 Hz, but that their hearing sensitivity was strongest at 300 Hz. This doesn’t mean that the fish can’t hear each other. They just don’t specifically tune into the distress calls of their own species, perhaps because the teeth grinding is a relatively new phenomenon. They also must listen for other sounds, such as prey movements.

The fish have what are known as pharyngeal jaws, meaning a second set that’s located in the throat which manipulate prey and aid in its swallowing. And now we know that these jaws have another function.

Read more at Discovery News