Scientists have identified a mysterious whale song that suggests the existence of a new whale species living in the Antarctic.
That's at least based on recordings recently described in the Journal of Marine Mammal Science, which details how the unique noise is unlike any other made by beaked cetaceans, raising hope that it could be coming from a completely new species.
Though, there is still the possibility that the song could be from one of a few known species of beaked whale.
Beaked whales, while they comprise the second-largest family of cetaceans (the group containing whales and dolphins), are one of the most poorly known groups of all large mammals.
There are 22 known species of beaked whale, and all of them spend most of their time in elusive deep waters, rather than near the surface. These animals are best recognized by their unique songs, which they use to navigate.
This latest song is known as the Antarctic BW29 signal, and was recorded by a hydrophone array towed 200 meters (656 feet) behind a research vessel sailing the waters near the South Orkney Islands, South Shetland Islands, and Antarctic Peninsula.
The team of scientists, led by Jennifer Trickey of the Scripps Institution of Oceanography, at the University of California, recorded the Antarctic BW29 signal more than 1,000 times during 14 separate recordings. And because of its unique timing and composition of signals, they believe it belongs to a new whale species.
"Given that new species of beaked whale are still being discovered, the source of these Antarctic signals might be a species that has yet to be identified," the researchers told BBC Earth.
Scientists are sure Arnoux's beaked whales or Cuvier's beaked whales aren't making the noise, because the signal doesn't match their songs. (Scroll to read on...)
But it could belong to a strap-toothed whale, a southern bottlenosed whale or a Gray's beaked whale, according to the study. Though, it's extremely rare that a strap-toothed whale would be found so far south, while the noise is the wrong frequency for a Gray's beaked whale. That leaves the southern bottlenosed whale as the most likely match.
And yet, because the whale's relative, the northern bottlenose whale, makes very different calls, experts speculate that the southern species probably vocalizes in a similar way - unlike the Antarctic BW29 signal.
On top of everything else, the researchers also recorded a second unique call on six other occasions, dubbed Antarctic BW37, which was produced at a higher frequency.
"It remains unknown whether this belongs to a different beaked whale species than the one producing Antarctic BW29," the researchers wrote.
According to a popular theory, the frequency of a whale's song is usually linked to its size. If this is true, then it's possible that a southern bottlenose whale may make the Antarctic BW29 song, while the higher pitched Antarctic BW37 song could belong to a smaller Gray's beaked whale.
Furthermore, it is possible that a single species could sing at different frequencies and explain for both the Antarctic BW29 and Antarctic BW37 signals - though no known beaked whales have demonstrated this talent.
Scientists are really just beginning to understand the mechanics of how whales hear their songs so well, even while deep underwater. And the same can be said of what kinds of songs they produce, at least when it comes to beaked whales. Only by conducting further research can scientists gain better insight into beaked whales and their songs, and possibly solve the mystery of the unique Antarctic BW29 signal.
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