Yes, lizards do have lungs. As reptiles, these organs are central to their respiratory system, allowing them to obtain oxygen from the air, efficiently exchange gases and support their metabolic needs in terrestrial environments.
The Presence of Lungs in Lizards
Lungs are a defining feature of terrestrial vertebrates, enabling lizards to extract oxygen from the atmosphere. Unlike aquatic animals with gills or amphibians that absorb oxygen through their skin, lizards depend solely on their lungs. Their tough keratin scales prevent cutaneous oxygen absorption. Reptilian lungs also feature a greater surface area for gas exchange compared to amphibian lungs, making them more efficient for terrestrial life.
The Mechanics of Lizard Respiration
Lizards breathe using their chest wall muscles to inflate and deflate their lungs. During inhalation, rib muscles contract, pulling ribs forward and outward to expand the chest cavity and draw air in. As the ribs move outward, they also slightly pull the vertebrae in the spine backward, further increasing the body cavity’s volume. This method is called costal ventilation.
Lizards lack a diaphragm, the muscular sheet mammals use for breathing. Instead, their respiration relies on intercostal muscle contraction and relaxation, altering body cavity volume to move air. For exhalation, rib muscles relax, allowing ribs to move inward, reducing chest cavity volume and expelling air.
Diverse Respiratory Adaptations Among Lizards
Lizard lung structures vary across species, from simpler single-chambered (unicameral) lungs to more complex multi-chambered (multicameral) lungs. Unicameral lungs are typically sac-like with internal folds called faveoli for gas exchange, while multicameral lungs have multiple interconnected chambers. For example, monitor lizards, known for their active behavior, possess complex multicameral lungs with many chambers, sometimes as many as 12 per lung. These chambers likely function as bellows to facilitate air movement.
Some lizards, such as monitor lizards and bearded dragons, supplement lung ventilation with “gular pumping.” This involves rhythmic contractions and expansions of the throat muscles to force air into the lungs, providing an accessory breathing mechanism. Gular pumping assists lung ventilation, especially during locomotion when movement muscles might constrain breathing. Certain semi-aquatic lizards, like some anoles, exhibit a unique adaptation: they can rebreathe a bubble of air trapped on their snouts while submerged, extending their dive times. This rebreathing mechanism allows them to stay underwater for extended periods, sometimes up to 18 minutes, by utilizing the oxygen within the bubble and potentially releasing carbon dioxide into the surrounding water.