Mysterious sounds in the Mariana Trench
Unknown vocals recorded maybe from a baleen whaleRead out
Mysterious cries: Researchers have picked up unknown sounds from the depths of the Mariana Trench. The complex calls could come from there diving baleen whales, but they are not similar to any of the whale song known so far. The five-part reputation covers an enormous range of frequencies, ranging from a deep groan to a high squeak. Which whales make these sounds, must now be examined.
Whales are known for their sometimes complex sounds. The long humming sounds and stanzas of the humpback whales can be heard for several kilometers, because the pressure waves of the sound are effectively transmitted by the water. But also dolphins and orcas communicate via sounds and a whitetail even learned to imitate the human voice.
But what Sharon Nieukirk from Oregon State University and her colleagues in the Mariana Trench heard is something completely new. The researchers had evaluated records of autonomous diving gliders, which were equipped with microphones and sensors for months in the area of the deepest moat of the earth on the way.
From groaning to squealing
The shots sounded a completely unknown reputation: "It's very own and has some really weird components, " Nieukirk says. Thus, the five-part sequence lasts between 2.5 and 3.5 seconds and covers an unusually large spectrum of frequencies. The pitches of the enigmatic vocals range from a low 38 hertz to a high, almost metallic-sounding 8, 000 hertz.
The biologists suggest that these sounds are from a whale. Of which, however, is unknown. "The low-frequency, moaning part is typical of baleen whales, " explains the researcher. "But the high, sharp, almost nasal sound makes this sound truly unique." Most likely, the unknown singing resembles a call made by the minke whales (Balaenoptera acutorostrata) in the Great Barrier Reef. display
That's the strange sound:
Your browser does not support the audio element.A minke whale might be the originator of the mysterious sounds - but surely this is not. The Australian
This widespread on almost the entire northern hemisphere Walart is known to use regionally very different sounds for communication. For example, a minuscule, pulsed sequence of deep tones is typical for minke whales in the Atlantic, while in the North Pacific, boing sounds and complex tone sequences are typical.
This versatility could indicate that a minke whale gave the mysterious calls from the Mariana Trench. "We do not know much about the distribution of minke whales in the low latitudes, " says Nieukirk. "They hardly ever stop at the surface of the sea and usually live on the open sea. But they call relatively often. "
Search for source of the sound continues
If the mysterious call comes from a minke whale, but this raises further questions. This is because these marine creatures typically call in winter and during the mating season. But the Wallaut baptized "Western Pacific Biotwang" was recorded again and again throughout the year. "If this is really a mating call, why do we hear it all year round?" Nieukirk asks.
The researchers hope that further acoustic recordings will unlock the secret of this Wallaut. It is possible that these whale sounds were recorded earlier, but little was recognized about their extremely wide frequency range. "We hope that other researchers will identify these calls in old and new data and that we will find the source of that sound, " says Nieukirk. (Journal of the Acoustic Society of America, 2016; doi: 10.1121 / 1.4962377)
(Oregon State University, 16.12.2016 - NPO)