Species separated by inability of hybrid offspring to produce offspring of their own

because they are eaten by the frog and the frog getseaten by the snake and the snake by the eagle

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.