Whales are elusive creatures who roam the vast, open ocean. Because sightings of many species are so rare, we have to track these giant mammals by eavesdropping on their songs. And marine scientists recently picked a baffling new signal, which could be from a new species of beaked whale.
The Antarctic's frigid waters are home to at least five species of beaked whales, an especially poorly studied group because they rarely spend much time at the surface. But these beaked whales do echolocate with a very distinctive "frequency modulated (FM) upsweep pulse," which you might think of as a chirp. Each species also has its own unique FM pulse.
Last February, a research vessel towing four hydrophones sailed through Antarctic waters to listen for whale signals. Researchers found one particular signal, known prosaically as Antarctic BW29, as quite strange. They picked it up on 14 separate occasions, but Antarctic BW29 did not perfectly match any known species.
For example, the peak frequency was too high for Arnoux's beaked whales. And strap-toothed whales aren't usually this far south. The three other known beaked whale species also imperfectly matched the criteria. The author's conclude, "the source of these Antarctic signals might be a species that has yet to be identified."
Of course, it's also possible the known ranges of other beaked whales are wrong or that there is more variation between whales of the same species than previously thought. But it is sobering to realise that even in 2015, our knowledge of some whales is so patchy that we have to stare at the spectrograms of a few recordings to divine something new. [Marine Mammal Science via BBC]
Picture: An Arnoux's beaked whale in Antarctica. Soler97/Creative Commons