Why do whales sing? Could it have something to do with breeding, or feeding, or navigation — or is it just a simple longing to communicate? All of those are theories, but scientists don't seem to have reached a consensus.
These underwater giants make all sorts of sounds, from clicks, grunts and squeaks to sustained, otherworldly melodies.
According to research biologist John Calambokidis, blue whales make two distinct calls.
The "A" call is pulsing and almost mechanical...
...while the "B" call is a low frequency hum barely registered by human ears...
A third sound, the "D" call, is described by ocean acoustician Mark A. McDonald as a "non-song communicative" call...
What researches call a whale song is a sequence of these sounds that can last 20 minutes. Male humpbacks in particular will repeat the same song over and over again for hours.
In fact, it's probably the humpback's song that people are most familiar with, thanks to the album "Songs of the Humpback Whale," originally released more than 40 years ago and still available on CD.
All of the whales in one region will sing the same song, but the song changes over time. Researchers are currently puzzling over a mysterious drop of pitch in the songs of the blue whale. A study cited in Wired Magazine says the pitch is now 31 percent lower than it was in the late sixties, and the change is worldwide, not just in one region. One possible explanation is that the whales had to sing at a higher pitch decades ago when the population was at its lowest point because of whaling. The higher-pitched song traveled farther in the water. Now, with the numbers increasing, their songs don't have to reach as far to be heard by another blue whale.
If you want to spend even more time listening to whale sounds, Scientific American's Whale Song Project wants you. Go to Whale.fm for an online experiment in crowdsourcing that asks for the public's help in figuring out what whales are saying. It asks you to listen to various whale calls and put the ones that sound alike into groups. A recent NPR story has more details on the project.