Toadfish is the common name for a variety of species from several different families of fish which have a toad-like appearance in common. They are known for their ability to produce sound with their swim bladders.

The endless motor-like sounds are produced by their strong muscles pressing against their balloon-like bladders. They hit the bladder about 6,000 times a minute -- twice the speed of a hummingbird's wings -- and do it during a mating season that usually starts in May and ends in September. The loud hum can last for more than an hour at a time.

Jim Covel, Monterey Bay Aquarium's director of guest experience -- who has experience with this species -- said the sound that disturbed the residents likely comes from "lonesome males" trying to attract mates.