Reptiles That Breathe With Lungs

The animal kingdom is subdivided into six categories: birds, fish, amphibians, insects, mammals and reptiles. Most people are familiar with reptiles such as crocodiles, glamorized as wild outback beast by popular television series such as "Crocodile Dundee" and "The Crocodile Hunter." However, the reptile family consists of a much wider array of creatures than just crocodiles and alligators. With the exception of a few rare species, all reptiles breathe air, lay eggs and have scale-covered skin. While some species of reptiles have evolved to use other methods to aid in breathing, all reptiles have lungs, which are their primary source of respiration.

  1. Characteristics of Reptiles

    • Reptiles are divided into four orders: Crocodilia, Spenodontia, Squamata, and Testudines. Crocodilia, as the name suggests consist of over 23 species of crocodiles, gavials, alligators and caimans. Squamata are a large group of reptilian animals consisting of lizards and snakes. Spenodontia are a smaller group of reptiles consisting of two species, including a lizard-like reptile from New Zealand, called the tuatara. Testudines classify turtles and tortoises. All reptiles breathe using lungs, however most vary in their methods respiration and secondary methods of gas exchange.

      All reptiles use lungs in order to breathe, but certain types have evolved to develop secondary methods in respiratory assistance.

    Breathing in Turtles

    • Breathing in turtles is systematically quite complex. A turtle's lungs are attached to the top of the rigid shell, which does not allow for much room for expansion upon inhalation. While the turtle's primary source of respiration comes from the lungs, they have adapted methods to work around their own limitations. Some turtles have a layer of muscle that wraps around the lungs. This muscle contracts, allowing turtles to breathe while resting. Some turtles draw their limbs inside their shells in order to push out the air from their lungs and inhale once they protract their limbs. Turtles take in large amounts of air and store air in their lungs, rather than taking short breaths as humans do. For this reason, they are able to go for long periods of time between breaths. Aquatic turtles have evolved to modify their respiratory system over time. They have more permeable skin than most other scaly reptiles, allowing for some gas exchange. They store oxygen in the cloaca, which is an organ found in all birds, reptiles and amphibians.

    Breathing in Squamates

    • Squamates use muscles that lie along the vertebrae to ventilate the lungs. This is the same muscle that allows squamates to move. For this reason, squamates must hold their breath when moving, however, some species use muscles on the floor of the mouth to breathe while in motion.

    Breathing in Crocodilians

    • Crocodiles may be more similar to humans than one would think. They have a diaphragm, very similar to that of a mammal. However, the stature of crocodilians cause more difficulties in breathing, as there is less room for lung expansion. Crocodilians breathe by pulling the pubis muscle back and bringing the liver down to make room for the lungs to expand.

    Secondary Palates

    • Most reptiles have a secondary palate, which allows for breathing while swallowing food. Crocodillia also have a secondary palate, which allows them to continue breathing for long periods of time, while under water.