Final answer:
All mammals have lungs as the main organs for breathing. Lung capacity varies among different animals based on their activities. Birds have additional air sacs that enable efficient and unidirectional airflow through the lungs.
Step-by-step explanation:
All mammals have lungs that are the main organs for breathing. Lung capacity has evolved to support different animals' activities. For example, cheetahs have evolved a higher lung capacity to provide oxygen to their muscles during fast running, while elephants have a high lung capacity due to their large body size. In birds, the presence of air sacs allows for efficient unidirectional airflow through the lungs, enabling them to obtain oxygen even at high altitudes.
Learn more about Lung capacity in different animals