Pythons Grow Bigger Hearts at Mealtimes

March 2, 2005

Burmese pythons like a meal they can really get their fangs around, especially since the snakes are known to go half a year or more between meals. That gustatory pause is merely one of pythons' more remarkable adaptations.

New research shows that when the reptiles swallow whole rats, birds, and other prey, the pythons' hearts temporarily grow bigger.

Scientists in California say the snakes experience a 40 percent increase in heart muscle mass within 48 hours of feeding. The change enables the pythons to meet the metabolic demands of digesting a meal.

What's more, the process is fully reversible, with the snakes' hearts shrinking back to their original size once feeding ends.

Pythons can offer new insights to understanding heart growth in other species, including humans, according to researchers behind the discovery, which is reported in the current issue of the science journal Nature.

One of the world's largest snakes, the Burmese python can grow as long as 25 feet (7.6 meters) and weigh as much as 200 pounds (90 kilograms). Native to Southeast Asia, it preys on mammals, birds, and other animals, which the reptile swallows whole. But python meals are few and far between.

"These animals have a remarkable ability to shut down their metabolism between meals," said James Hicks, a professor of ecology and evolutionary biology at the University of California, Irvine.

"We currently have 1.5-kilogram [3.3-pound] pythons in the lab that have not eaten for three months and have only lost one to ten grams [four to thirty-five hundredths of an ounce] of weight," noted Hicks, who is also the study's lead author.

But when these reptiles do feed, Hicks added, they often tackle prey that is 50 to 100 percent the size of their own body mass. Such meals require a considerable digestive effort.

"Some investigators have reported as much as a 44-fold increase in metabolism during digestion," Hicks said.

Metabolic Demands

Hicks and his colleagues investigated how Burmese pythons meet the metabolic demands of digestion.

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