Two subspecies of mice live in a desert ecosystem. Subspecies 1 is large, dark tan, and has longer legs than Subspecies 2. Subspecies 2 is small, light tan, and has shorter legs than subspecies 1

they float because they are less dense than the water itself

something denser than water, like a rock, will sink to the bottom

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.