According to recent studies by field, the total npp from aquatic ecosystems is approximately the total npp from terrestrial ecosystems.

the answer is :

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.