Strange underwater noises, known as “biotwang” sounds, have puzzled scientists since they were first heard near the Mariana Trench in 2014. These odd noises, described as a combination of low grumbling and high-pitched metallic ringing, are reminiscent of eerie sounds from sci-fi movies. For years, the source of these noises was unknown, though they were suspected to be connected to marine life. A recent study has now confirmed that Bryde’s whales (Balaenoptera edeni) are responsible for making these unique sounds. Researchers believe the whales may use these noises as a way to communicate across the vast ocean.

Biotwang discovery and analysis

The biotwang noises were initially recorded by underwater gliders during an acoustic survey of the Mariana Trench as per a study published in the journal Frontiers in Marine Science. Scientists struggled to identify the origin of these unusual sounds. In 2016, researchers proposed that the sounds likely came from large baleen whales like blue whales or humpback whales, though they could not be certain at the time.

It wasn’t until 2023 that the source was definitively traced back to Bryde’s whales, thanks to new advancements in artificial intelligence (AI). The AI tools sifted through over 200,000 hours of recordings to help researchers identify the biotwang calls.

Tracking Bryde’s whales

Ann Allen, an oceanographer at the National Oceanographic and Atmospheric Administration (NOAA) Pacific Islands Fisheries Science Center, led the study. Her team discovered that the biotwang noises aligned with the migration patterns of Bryde’s whales, confirming their involvement.

The researchers observed Bryde’s whales in the region and recorded several making the sounds, further solidifying the connection. Interestingly, the biotwang noises were only detected in the northwest Pacific, suggesting that these calls might be unique to a specific population of whales.

While the exact purpose of the biotwang calls remains unclear, scientists believe they may be a form of long-distance communication.