Koala's Unique Vocal Organ Gives an Elephant-sized Mating Call [VIDEO]

Male koalas possess a specialized sound producing organ never before seen in any other land-dwelling mammal, according to new research on the marsupials during the mating season. Usually lethargic and unremarkable, koalas are anything but during an attempt to attract a mate, producing a guttural, reverberating noise that is about 20 times deeper than it should be for a animal of its size.

Scientist have long wondered what gives koalas their extraordinary bass. But a team from University of Sussex has found out. Male koalas have a previously undiscovered organ at the back of their throats. Known as vocal folds, these organs lie just above the koala's larynx and help the males produce the deep mating noises needed to win the affections of the ladies.

"We have discovered that koalas possess an extra pair of vocal folds that are located outside the larynx, where the oral and nasal cavities connect," Benjamin Charlton of the University of Sussex said in a news release. "We also demonstrated that koalas use these additional vocal folds to produce their extremely low-pitched mating calls."

The bass of the koala's mating call is incredibly low-pitched, the researchers report, noting that such low reverberations are usually found in animals the size of an elephant.

The koala's mating song sounds like a creaky barn door on the inhale and a loud, unapologetic burp upon the exhale. Combined, as journalist Ed Young puts it, the noise resembles an angry Wookiee.

The koala's vocal folds are two long, fleshy lips in the animal's soft palette, connecting to the larynx at the junction between the oral and nasal cavities. In appearance, the organ is not easily distinguishable from the laryngeal vocal folds of other mammals, but their location is highly unusual, the researchers report.

"To our knowledge, the only other example of a specialized sound-producing organ in mammals that is independent of the larynx are the phonic lips that toothed whales use to generate echolocation clicks," Charlton said.

The research team is planning future investigation into whether these vocal adaptations are truly unique to koalas. The current study is published in the journal Current Biology.