Humpback Whale Songs Can Travel Over 16,000 Kilometers

The incredible distances that humpback whale songs travel are made possible by a unique feature of the ocean environment. Sound waves are effectively trapped in a specific layer of water known as the "deep sound channel," or SOFAR channel. In this channel, typically found at a depth of about 1,000 meters, the combination of temperature and pressure causes sound to travel at a minimum speed. When low-frequency sounds from whales enter this channel, the waves are refracted and guided horizontally, preventing them from escaping to the surface or scattering on the seafloor. This process allows the sound to travel for thousands of kilometers with very little loss of energy.

These complex vocalizations, which can last from 20 minutes to several hours, are performed exclusively by male humpback whales and are primarily associated with the breeding season. The songs are not random noises but are intricately structured with repeating units, phrases, and themes, much like human music. While the exact function is still being studied, scientists believe these songs play a crucial role in sexual selection, possibly to attract females or establish dominance among competing males.

The study of these songs revealed a fascinating form of cultural transmission in the animal kingdom. Each population of humpback whales has its own distinct song, which constantly and slowly evolves. Sometimes, a completely new song from a neighboring population is adopted and spreads rapidly, a phenomenon known as a "song revolution." The discovery and popularization of these underwater symphonies are relatively recent. While the earliest known recording was made in 1949, it was biologist Roger Payne's 1970 album, "Songs of the Humpback Whale," that introduced the world to these haunting sounds and ignited global interest in whale conservation.