Scientists recorded a refined sound that likely represents the discovery of a new baleen whale call. The call has been registered in the Mariana Trench, Earth’s oceans deepest known area, which gives any sound underwater a wide frequency range. The sound was titled the “Western Pacific Biotwang, hertz” and it is similar to another whale call named “Star Wars.”
The call includes five parts lasting between 2.5 and 3.5 seconds. The last part of the sound includes deep moans at frequencies as low 38 hertz and a metallic finale that reaches the 8,000 hertz.
The newly discovered sound is believed to be produced by dwarf minke whales, a mysterious animal hard to study because it does not spend much of its time on at the surface. Minke whales produce the sound “Star Wars” that includes “boings” in the North Pacific and low-frequency pulse trains in the Atlantic.
Researchers from the Oregon State University Hatfield Science Center recorded and analyzed the sound. Sharon Nieukirk, senior faculty research assistant in marine bioacoustics at Oregon State, stated that the call is very distinct. She added that the part of the recording that plays a low-frequency moaning is typical of baleen whales. The call also shows a twangy part that Nieukirk said to be unique.
Recording the ‘Western Pacific Biotwang’ call in the Mariana Trench
The sound was recorded using passive acoustic ocean gliders, which are instruments that can travel autonomously for months. The equipment can dive up to 1,000 meters, allowing the study of whales that mostly live in deep waters.
The minke whales are considered baleen whales because they feed by using baleen plates in their mouth to filter krill and small fish. Data shows they produce regionally specific calls, including the “Star Wars” call.
Nieukirk explained that the species is the smallest of the baleen whales, has an inconspicuous blow and often lives in areas where high seas make it difficult to study them. She added that dwarf minke whales frequently call, which makes them good study animals.
The new “Western Pacific Biotwang” sound comes with many mysteries because it was recorded throughout 2016. Baleen whale calls are often related to mating, and they are heard mainly during the winter. To start unveiling the truth behind the new marine sound, Nieukirk stated that her team at the Cooperative Institute for Marine Resources Studies has to calculate how often the new call happens during summer and winter.
Nieukirk warned analyzing the sound has not been easy due to its wide frequency range mainly caused by the Mariana Trench.
The Mariana Trench is the deepest known part of the Earth’s oceans and feature depths that goes up to 36,000 feet. It is located between Japan to the north and Australia to the south.
The only clue scientists have is that the “Western Pacific Biotwang” is similar to the “Star Wars” sound, which is produced by dwarf minke whales on the Great Barrier Reef off the northeast coast of Australia. The Star Wars call also has a complex structure, frequency sweep and metallic conclusion.
The findings were published in the Journal of the Acoustic Society of America this week.
Source: Oregon State University