If you live by the sea, have you ever heard an annoying humming that keeps you awake? Before you bang indignantly on your neighbors' doors, consider that it might be horny fish making the noise. One fish in particular is an international phenomenon.
The midshipman fish has, all things considered, one of the more pleasant mating rituals in nature. Rather than fighting among themselves or biting the hell out of their prospective mates – as sharks do - they try to out-sing each other. The males get together in groups and start a low humming sound. He who hums best gets the girl.
The group of fish humming together gets the attention of the local townspeople. Low-frequency humming carries over large distances, traveling through the ground, penetrating walls, and rattling windows. This is why we hear the bass when cars playing loud music come by the house, rather than the higher notes. It's also why people close to the ocean hear a humming at night loud enough to keep them up. (Just as a bonus, the fish are nocturnal.) These people did not know where the humming was coming from, which is why power lines and local highways got a lot of complaints until someone turned their eyes on the ocean.
Since it goes against the grain nowadays to say "slaughter all those amorous fish so that I may sleep," nothing much has been done about the problem except establish its size. Although it's confined to mating season, it's a global phenomenon. Towns as far apart as Seattle, Washington and Hythe, England have had problems with the midshipman.
Top Image: USGS