Male humpback whales are known for their long, vocal songs. A humpback's song can last as long as 30 minutes, and can be heard underwater miles away.

Photo courtesy NOAA

The Same Old Song

In the past hundred years, the world's attitude toward whales has changed drastically. The animals are no longer seen as fearsome creatures, as represented in "Moby Dick," and worldwide protection efforts have significantly reduced whale hunting. Through extensive observation, scientists have demonstrated that whales are generally peaceful, playful creatures, and that they posses a high level of intelligence. Today, whales seem pleasantly familiar to us, while in the past, they were monstrous strangers.

But even now, whales are still a mystery of sorts. A lot of information gathered by whale researchers has raised new puzzles about the animals. Whale communication is particularly perplexing. Male humpbacks (also known as bulls), the most vocal whales, emit a complex sequence of low moans, high squeals and clicking noises. These noises are sometimes combined in songs that last as long as 30 minutes. The astounding thing about these songs is that whales will repeat them over and over again, verbatim. And in a particular region, every male will sing the same song, making small changes every once in a while so that it evolves into a completely different song over time.

This behavior seems to be related to reproduction. During mating season, a male humpback starts the long song sequence, cutting it short only to join a passing female whale (also known as a cow), escorting her and her calf as they swim along. Eventually, the bull and cow may dive deep into the ocean, presumably to mate. It seems logical that the male's song is analogous to the bright plumage that birds display to attract a mate, except that the sound carries over many miles, attracting any other male humpbacks in the area. It's very odd that a male would call his own competition to him, unless he actually wanted to test his strength against others. Some whale researchers believe that the songs are actually acoustic contests of strength, similar to rams butting heads, or deer clashing their antlers.

Whales don't produce sounds the way we do. Our vocal-cord system wouldn't work too well underwater. Instead, whales produce sound by moving inhaled air around the nasal cavity in front of their blowholes. In toothed whales, the sound-making system involves a complex arrangement of fatty tissues. In sperm whales and dolphins, these sound structures are so large that they form a pronounced bulbous shape on the forehead. Scientists still don't understand exactly how whale sound production works, but they know it is unlike anything else we've encountered in the animal kingdom.