Just like our land-faring friends, many fish also make their own unique sounds. Their goal with these calling cards is often to woo potential mates or frighten off predators, but sometimes it’s simply a sign of distress or a byproduct of motion.
However, unlike the vocal chords utilized by many terrestrial species, these soniferous fish have other means of producing sound—drumming, stridulation and hydrodynamics. And the sounds almost always occur at low frequencies.
Most fish have a swim bladder—a pocket of air in the abdomen that helps control buoyancy. Some fish also have what’s called a sonic muscle attached to, or near, the swim bladder. When the sonic muscle contracts (in some cases, thousands of times per minute), it causes the swim bladder to rapidly inflate and deflate, creating sound.
The sound emanating from a vibrating swim bladder typically resembles the beating of a drum, but variations exist that can sound more like humming, growling or grunting. In the male toadfish, for instance, the vibration is reminiscent of a foghorn.
Check out this video to hear a midshipman fish growl:
Stridulation is a fancy term for the way some fish press their bones or teeth together to make noise. Think of the familiar way a cricket rubs its legs together to chirp.
Sometimes, stridulation is purposeful. The channel catfish, for example, will rub its fins together to produce sound. In some instances, stridulation is simply the byproduct of a noisy eater—some seahorses have been known to make clicking sounds while feeding.
The low-frequency sound produced when a fish rapidly changes its speed or direction is called hydrodynamic sound. Scientists believe hydrodynamic sound could have important implications in predator/prey dynamics—a noisy swimmer may inadvertently attract predators.
To learn more about so-called soniferous fish, listen to this week’s A Blue View podcast: