Digestion vs Movement in Burmese Pythons

Boas and pythons can survive long periods without food. Literature reports pythons fasting for as long as 36 months. Work done by Stephen Secor and colleagues have demonstrated that python stomachs that have not been used for awhile  produce enough hydrochloric acid to change the pH from 7 to 1.5 in 48 hours, and the snakes maintain that pH for as long as six days while the meal is digesting. The pancreas is able to double its mass so that it can increase its enzyme production 6-20 times. The small intestine also doubles its mass, increases its enzyme production, and its ability to absorb nutrients.  that have eaten a large meal up-regulate the performance of their digestive systems. Now Secor and White have examined the blood flow of snakes after they have eaten a large meal and investigated what the snake does when it has to move while it is digesting food. They asked the question does the moving snake, carrying a gut full of food, alter its blood flow?  They used perivascular blood flow probes to measure blood flow in the several major arteries and veins. Snakes that were fasting and crawling increased their heart rate 2.7 times, and their cardiac output 3.3 times. A snake digesting a rodent that was about 25% of the snake's body weight increased its heart rate 3.3 times and its cardiac output 4.4 times. A crawling snake reduced its blood flow to to the digestive systems by 81%. Thus, Burmese pythons prioritize their blood flow, sending more blood to their muscles and less blood to the digestive system when they have to digest food and move at the same time. This has obvious survival value for the snake.

S. M. Secor and S. E. White. 2010.Prioritizing blood flow: cardiovascular performance in response to the competing demands of locomotion and digestion for the Burmese python, Python molurus. Journal of Experimental Biology 213: 78-88.