How do animals breathe?

Animals breathe by taking in oxygen from the air or water and releasing carbon dioxide as a waste product. The specific mechanism of breathing varies among different types of animals, but the basic process involves inhaling air or water through specialized organs, such as lungs, gills, or tracheae, and exchanging oxygen and carbon dioxide with the circulatory system.

For example, mammals like humans breathe air into their lungs, where oxygen diffuses into the bloodstream through small air sacs called alveoli. The oxygen is then transported throughout the body by red blood cells, and carbon dioxide produced by cellular respiration is carried back to the lungs and exhaled.

Fish, on the other hand, use gills to extract oxygen from water. Water flows over the gill filaments, which are lined with tiny blood vessels, and oxygen diffuses from the water into the bloodstream while carbon dioxide diffuses out.

Insects and other arthropods have a network of small tubes called tracheae that deliver oxygen directly to cells throughout the body. The tracheae open to the outside through small holes in the body called spiracles.

Overall, the respiratory system of animals has evolved to meet the specific demands of their environment and lifestyle.