Thus, the frog breathes.
Amphibians do not use intercostal muscles for breathing, and frogs (like other tailless amphibians) do not have ribs at all. To draw air into their lungs, they use a specialized sublingual apparatus that moves the lower wall of the pharyngeal cavity.
When this wall lowers, the pharyngeal cavity expands — and air enters it through the nostrils; then the nostrils close with valves, the wall rises — and air is pushed into the lungs. It is these movements of the lower wall that we observe.
