Scientists and snake fans have long wondered how exactly boas and other constrictors can ingest massive prey without suffocating. Biomechanics researcher John Capano of Brown University found the answer somewhere in the 200-plus pairs of ribs that run the length of a boa’s body, reports NPR News. In new research published by the Journal of Experimental Biology, Capano and team explain that the snakes can shift their breathing to different areas of the body when the usual areas are otherwise engaged, per Science.org. The discovery came after researchers applied blood pressure cuffs to restrict rib movement in different areas. They then put a high-tech “little tiny helmet on the snake” to measure airflow, and analyzed rib and muscle movements using X-ray and nerve signals.
Like its spine and muscles, a snake’s lungs extend through much of the body. Per NPR, “the part of the lungs closest to the head is where gas exchange seems to take place … while the part of the lungs closer to the snake’s tail is more like an empty bag.” When the front ribs are restricted, the back ribs kick in to stimulate the baglike structure, which “operates like a bellows to draw air” into the front section of the lung. The research shows that snakes have exceptional control over where ventilation occurs in their bodies. It also explains a key to their evolutionary success: constrictors have more food options because they can hunt larger animals.
Fellow Brown researcher Elizabeth Brainerd explains: “As constriction was evolving, it was certainly impeding the ability of those animals to use the ribs in that area for breathing. And so there would have been pressure to evolve this modular breathing, to move breathing to a different part of the ribcage.” You can view an X-ray video clip on Science.org, and LiveScience offers a solid summary with additional visual aids to explain the process, perfect for sharing with any aspiring young herpetologist. (Read more biomechanics stories.)