On the water at night In the bay area or even in Seattle now, you can hear an odd low humming that starts at sun down and then ends at day break.
The sound comes from the male midshipman fish and now scientists have figured out why they make these sounds at night. They have linked it an internal clock hormone that produces melatonin which in human makes us sleepy, but in these nocturnal animals the chemical appears to turns them into underwater lounge singers trying to swoon the ladies.
There aren't too much on the looks department, so I guess they try to use that "old black magic" crooner method to attract a mate. :)