Anurans (frogs and toads) communicate largely through sound. Every species has a unique vocalization or “call.” The sound is made by passing air through a part of the throat called the larynx, similar to how we make sound. Most frogs also have a pouch under their throats (vocal sacs) that stretch during calling to amplify the sound. Calling is used by males to attract females for mating. While males may call individually, in many species they gather in groups, resulting in a chorus of calls. Aggregating may give males the advantage of attracting more females, although then they must compete for them. There is evidence that females select males based on how loud and/or low they call, causing natural selection for powerful calls (sexual selection). Frogs also use sound to communicate distress (if grabbed by a predator), defend territories, or other events.