Scientists have finally unraveled the mystery behind a bizarre quacking sound heard in the ocean.
The noise, nicknamed "the bio-duck", appears in the winter and spring in the Southern Ocean. However, its source has baffled researchers for decades.
Now acoustic recorders have revealed that the sound is in fact the underwater chatter of the Antarctic minke whale, the BBC reported.
Lead researcher Denise Risch, from the US National Oceanic and Atmospheric Administration (Noaa) Northeast Fisheries Science Center in Massachusetts, said that over the years there have been several suggestions, but no-one was able to really show this species was producing the sound until now.
The strange sound was first detected by submarines about 50 years ago. Those who heard it were surprised by its quack-like qualities.
The findings are published in the Royal Society journal Biology Letters.
