How do fish hear?

Sound travels as series of waves or vibrations through water. A fish's body is of similar density to the water around it, and these waves pass through it.  Waves in the sea... who'd have thought it?

The inner ear of a fish has a lot of bones knows as otoliths. These bones are much denser than water and the rest of the fish's body. These bones move more slowly in response to sound waves, allowing the fish's brain to interpret sound.

Sensitivity to sound differs among fish species. Because the gas in the swim bladder also varies in density, sound waves can affect it. It is thought that fish without a swimbladder, or a small or reduced swim bladder (many bottom-dwelling species) or a swim bladder not close or connected to the inner ear, have relatively poor sensitivity to sound. A fish with a swim bladder in close proximity to the inner ear increases hearing sensitivity.

So, when you see the sign in your local fish store that says "Please don't tap on the glass" you'll know why. Because fish can hear it!


Written by: Luke Williams
Photo credit: MaxPixel