PROVIDENCE, RI [Brown University] “Won’t bring much comfort to the unfortunate victims of a boa constrictor, but dinner puts the snake in a tough spot. The mechanic of squeezing a creature to death and then swallowing it whole creates pressure on the boa’s ribs and lungs, limiting its ability to fill its lungs with oxygenated air.
Still, the snakes have clearly overcome — some might even say mastered — the challenges of breathing while eating, and researchers have finally figured out how. A study published in the Journal of Experimental Biology explains how boa constrictors are able to adjust the region of the ribcage they use to inhale, depending on whether they are resting, contracting or digesting.
“By showing how snakes were able to circumvent the mechanical stresses of constriction and ingestion of large prey – the very things that set them apart from other limbless elongated animals – this study offers a new perspective on the evolution of snakes. “, said John Capano, lead author of the study. , who earned her doctorate. from Brown University in 2021 and is now a Postdoctoral Research Associate in the lab of Matt Fuxjager, Brown Associate Professor in the Department of Ecology, Evolution, and Organismal Biology.
Snakes don’t have a diaphragm, so they rely entirely on the movements of their ribs to breathe, Capano said. To quantify individual rib movements, Capano and Elizabeth Brainerd, professor of biology and medical sciences at Brown, used a 3D imaging technology developed at Brown University called X-ray reconstruction of morphology in motion (XROMM). , which can show the rapid skeletal movement of living creatures. XROMM combines 3D models of bone morphology with motion data from X-ray video to create highly accurate reanimations of bones moving through space (e.g. flying birds, jumping frogs and snakes who breathe).
In the experiments, Capano and Brainerd attached a blood pressure cuff around the boa constrictors’ ribs to restrict their movement. Capano attached tiny metal markers to two ribs of each reptile — one set of markers a third of the snake’s body and another halfway through — to visualize how the ribs moved using X-rays. Then he placed a blood pressure cuff on the ribs in both areas and gradually increased the pressure to keep the ribs from moving.
Some of the snakes reacted to the sensation of the cuff by hissing defensively, filling their lungs with air and expanding their ribs. “The hiss gave us the opportunity to measure some of the biggest breaths snakes take,” Capano said.