Vocal sac

The vocal sac is the flexible membrane of skin possessed by most male frogs and toads.

Muscles within the body wall force the air back and forth between the lungs and vocal sac.

The primary purpose of the vocal sac is to amplify the advertisement call of the male, and attract females from as large an area as possible.

Modern frog species (neobatrachians and some mesobatrachians) which lack vocal sacs tend to inhabit areas close to flowing water.

The males of the two species of this family scoop recently hatched tadpoles into their mouth, where they move into the vocal sac.