Animals That Use Lungs for Breathing

Terrestrial animals such as mammals, birds, amphibians and reptiles breathe with lungs. All organisms require energy for any work that they do, and this energy is generated by respiration, which requires oxygen. Organisms take in oxygen as they inhale, then the air reaches lungs, where oxygen is absorbed and carbon dioxide is released as animals exhale.

  1. Mammals

    • Mammalian lungs are made of a large number of small sac-like structures known as alveoli. Each alveolus is surrounded by blood vessels, and it is in these structures that the gaseous exchange takes place. Air enters a mammal's body through its nostrils or mouth, from where it travels through the windpipe to reach the trachea. The trachea branches into two bronchi, one reaching each lung. The bronchi divide into smaller branches known as bronchioles. Each bronchiole carries air to one alveolus. Air is driven in and out of the lungs by the movement of the muscular diaphragm and in part by the relaxation and contraction of the rib cage. Inhaled air and exhaled air move through the same path in and out the lungs in mammals such as humans, dogs and cats.

    Birds

    • Birds require a large amount of energy for flying. Birds breathe through lungs, but the air in their lungs flows in one direction, providing a constant a supply of oxygen. Birds have additional sacs spreading out the lungs into their body, and but they do not have a diaphragm that drives air in and out their lungs as in humans. Instead, this function is carried out by their body's muscles.

    Amphibians

    • Amphibians can live on land or in water. Although they do most of their breathing with their skin, they have lungs --- and, when some species are young, they use gills to breathe. Amphibian lungs are very simple, so much of their breathing is through their skin, where oxygen passes through it into blood vessels just below the skin. This type of breathing is called cutaneous respiration.

    Reptiles

    • Unlike amphibians, reptiles do not have gills during any stage of their lifespan. Also, their dry and scaly skin prevents them from breathing through their it. Hence, these animals rely entirely on their lungs for respiration. Reptiles lack the diaphragms that mammals have. Instead, their lungs inflate and deflate by the expansion and contraction of their ribcage. Also, similar to mammals, air flows in and flows out of reptilian lungs through the same path.