Sometimes a whale just wants to change its tune.

That’s one of the things researchers have learned recently by eavesdropping on whales in several parts of the world and listening for changes in their pattern and pitch . Together, the new studies suggest that whales are not just whistling in the water, but constantly evolving a form of communication that we are only beginning to understand.

Most whales and dolphins vocalize, but dolphins and toothed whales mostly make clicking and whistling sounds. Humpbacks, and possibly bowheads, sing complex songs with repeated patterns, said Michael Noad, an associate professor in the Cetacean Ecology and Acoustics Laboratory at the University of Queensland in Australia.

Birds may broadcast their social hierarchy among song-sharing populations by allowing the dominant bird to pick the playlist and patterns. But how and why whales pass song fragments across hundreds of miles, and to thousands of animals, is far more mysterious.

The biggest question is why whales sing at all.

“The thing that always gets me out of bed in the morning is the function of the song,” Dr. Noad said. “I find humpback song fascinating from the point of view of how it’s evolved.”