Snakes require oxygen and breathe. Their respiratory system, while performing the same fundamental function as mammals, features distinct adaptations that allow them to thrive in various environments and lifestyles.
The Basics of Snake Respiration
Snakes primarily breathe using a single functional lung, typically the right lung, elongated to fit their slender body. Some species, like boas and pythons, may have a smaller, vestigial left lung, but it contributes minimally to gas exchange or is often absent. The functional lung has a respiratory portion near the head for gas exchange, and a posterior, thin-walled air sac that acts as a reservoir but does not participate in gas exchange.
Air enters through nostrils, leading to the glottis. The glottis, a small, vertical slit behind the tongue, opens into the trachea (windpipe) when the snake breathes. Unlike mammals, snakes lack a diaphragm. Instead, they rely on muscles between their ribs to expand and contract their body cavity, creating pressure changes to draw air in and expel it. Inspiration is an active process involving muscle contraction, while expiration occurs as these muscles relax.
Unique Adaptations for Breathing
Snakes exhibit specialized adaptations to breathe effectively, particularly when swallowing large prey. The glottis is highly mobile. When a snake consumes a large meal, which can be wider than its body and take time to swallow, it can extend its glottis out of the side of its mouth. This allows the snake to continue breathing, acting like a snorkel.
For constricting snakes, breathing presents another challenge. These snakes can selectively use different sections of their rib cage to breathe. If one part of their body is constricting, other sections of their ribs can still expand and contract to ventilate the lungs. This modular lung ventilation ensures oxygen intake even during intense physical exertion. Additionally, some aquatic snake species have adaptations for underwater respiration, such as absorbing oxygen through their skin, known as cutaneous respiration. This allows them to remain submerged for extended periods, though they must still periodically surface for air.
Common Misconceptions About Snake Breathing
Common misconceptions exist regarding snake respiration. One misconception is that snakes can hold their breath for extremely long periods, similar to aquatic mammals. While many snakes can hold their breath for 15 to 25 minutes, and some aquatic species longer, they are air-breathing animals that must eventually surface. Sea snakes, despite their aquatic lifestyle, rely on lungs and cannot breathe water like fish.
Another false belief is that snakes primarily breathe through their skin or lack lungs. Terrestrial snakes rely on lungs for respiration. While some aquatic species can absorb oxygen through their skin, this is a supplementary mechanism, not their primary breathing method. The idea that snake breathing is “primitive” or that they lack lungs is incorrect. Their respiratory system is highly adapted to their unique anatomy and behaviors, allowing efficient gas exchange and survival across diverse habitats.