A Comparison of Mysticete and Odontocete Cetacean Acoustic Signals and Their Behavioral Consequences

Abstract

Odontocete cetaceans produce echolocation clicks, whistles, cries, chirps, and similar sounds. Mysticete cetaceans produce low-frequency moans, grunts, and thumps, and at least one species produces cries and chirps. The production of clicks by mysticetes has been controversial to date, but recent evidence suggests they emit pure frequency clicks up to 25 kHz. Mysticetes do not produce whistles. The organization of sounds implies that odontocetes use the high-frequency clicks for capture of individual prey (fish and squid). Mysticetes may or may not use their clicks for feeding, but if so they may be used only to locate masses of plankton and fish—not in locating single individuals. Again, the variety of signals produced by odontocetes in all seasons suggests a more intricate social organization. The complicated song of the humpback whale, produced only three months of the year, may have a wide variety of functions, but suggests a less complicated social organization outside of this season. Some of the low-frequency sounds of this mysticete may be needed for long-range communication, perhaps related to their extended migration.