Reptile is divided into 4 major types including Chelonia, Rhynchocephalia, Crocodilia, and Squamata; almost all reptiles that exist in this world are tetrapod vertebrates, event ought sometimes they spend most of their time in the water. If a reptile is spending their time in both dry place and water, so how do reptiles breathe? Do they have two respiratory organs to support their activities? Actually, a reptile is breathing through its lung, only small of them that use the skin to breathe such as sea snake.
How is the structure of Reptile's lung?
The structure of reptile's lung is quite complicated compare to us, the human. Each type of reptile has the different type of lungs. The Squamata types have a lung with axial musculature which is used during the locomotion, Lizard types have Buccal bumping that helps them to breathe; while Crocodilian is breathing with a muscular diaphragm. To breath with their lung, the reptiles collect the oxygen through their nose and send it to the lung. The system is quite similar with Mammalia; breathing is possible by increasing the volume of the body cavity which is caused by the contraction of the muscle. The negative pressure on the lung will make the oxygen possible to enter the lung. The air within the lung will be forced out when the volume of the body cavity is reduced. The reptile's lung is equipped with small pockets which are called as alveoli, but the breathing capacity of each type of reptiles has different amount event tough they all have alveoli on the wall of their lung. Alveoli system on crocodile is more effective compared to the snake because crocodile spends most of their time in water; while the snake is commonly found in dry place. But, a turtle has the different respiratory system, the inspiration in turtle occur when the contraction of two flank muscle occur; while the exhalation happens during the contraction of two muscle.
How do reptiles breathe when they are under the water?
Actually, a reptile is not breathing while they are under the water because their respiratory system is supported with lung which is only suitable when they are breathing on dry land or on the water surface. They can manage to stay longer under the water since they have the ability to hold their breath; it is possible because their metabolism system is only one-fifth and even one-tenth from Mammalia. Reptile breathing system is quite similar to Mammalia or human, they consist of inspirations and expiration; the different is only on their pause system. Some reptile has the ability to pause the breath longer than one hour especially the turtle and the sea snake, each type of reptile has the different rate of respiration depend on temperature and environment. Reptile usually dived under the water when they have the breathing pause; they will search for the surface when they need to breathe again. Even though their respiratory system is helped with permeable skin and modified cloaca, but they still need to collect the oxygen through their lung; it is the reason why we see the turtle swim on the surface of the water to collect oxygen.
