A group of researchers hasrecently stumbled across an unusual buzz, emerging only at nightfall and daybreak, within the dark reachings of the ocean. As they will indicate when their research is presented at the annual Ocean Science Meeting in New Orleans this week, this noise could be the dinner bell for a huge collection of creatures moving up and down the water column in order to feed en masse.
Using highly sensitive listening equipment, the team picked up an unidentified, low-frequency humming at a sea depth of around 200 to 1,000 meters( 660 to 3,300 feet ). No single type of marine beast could be matched to the noise, which was a mere three to six decibels above the background noise of the ocean.
You can listen to it below via NPR.
Its not that loud, it sounds like a buzzing or humming, and that goes on for an hour to two hours, depending on the day, said Simone Baumann-Pickering, an deputy researcher at UC San Diego and co-author of the study, in a statement.
This sound was coming from the mesopelagic zone, a dark world with limited food sources for many larger types of marine animal. Unlike surface waters, the light levels are insufficient for photosynthesis, so the general types of lifeforms found here are either herbivoresor scavengers feeding on the remnants of organisms or descending fecal matter.
What mysterious animal, or beings, could be making this low-frequency noise? superjoseph/ Shutterstock
Its not just a mostlydead region of the sea, though: A 2015 study estimated that up to 90 percent of the worlds fish may reside in this aquatic twilight zone, including many species that are as-of-yet unidentified. Is this novel, mysterious hum generated by anunknown species? According to the researchers, the voice may actually be the outcomes of a huge number of animals acting in unison.
Its already known that large crowds of fish, shrimp, and squid move upwards towards the surface waters to feed on surface plankton and nutrients. They do this as the sun sets, employing the darkness to mask their approach. When the sunshine rises, these small critters retreat back down into the darkness, hiding overnight for protection from sizable predators.
The researchers are convinced that this ascent and descent is responsible for producing the unusual noise although at present, they cant be sure which specific animal, or group of animals, is actually responsible. Theres a chance that this noise could signal when it is safe for a colony of fish to rise up and feed. If these beings are indeed emitting this sound as a sort of communication, it will wholly change our understanding of how various, deep-sea ecosystems fit together.
This enigmatic voice is the latest in a series of mysterious ocean noises. The Bloop, an ultra-low frequency audio heard on hydrophones( submerged microphones ), was briefly thought to be the call of an unknown ocean animal. Although nowadaysits thought to have been made by the cracking of an ice shelf, the oceans are still clearly plenty of curious noises for scientists to mull over. The Upsweepin the Pacific, for example, still remains unexplained.