Super Faster

A spherical bone particle is lodged in the pit cell. The long microvilli fold over the chamber for degradation. Magnification is 21,230X in this pseudocolored electron micrograph. Credit: Robert Pope.

Monday, April 16th, 2007--

The Burmese python can survive on just a few meals a year, according to Robert Pope, a researcher at Indiana University South Bend. Pope and his colleague Jean-Hervé Lignot, from Louis Pasteur University in France, have discovered a new type of cell in the snake’s digestive system that may help it live on so little. They presented the research at the Society for Experimental Biology’s Annual Meeting in Glasgow in the United Kingdom.

Pythons, which can grow to be more than twenty feet long, are “sit-and-wait feeders,” Pope says. They wait for food, like a cow for example, to walk by and then they strike, strangling the prey and unhinging their jaws to gulp it down. Pythons can eat twice their body weight at once; for comparison, humans “normally eat five percent of our own body weight or less per day,” Pope says. But despite infrequent dining and such big meals, Burmese pythons do not slowly savor dinner. When a python has a cow in its mouth, it is at risk for predation itself. Pope says that is why pythons have developed special adaptations for fast food intake.

As soon as the prey hits the python’s stomach, located anywhere from a few inches to a few feet past the mouth depending on the size of the snake, the python's organs enlarge. The stomach stretches; the intestine grows longer, making more space for digestion; and the heart gets bigger to pump more blood for quicker nutrient absorbtion. Even microvilli, tentacles attached to some stomach cells, stretch out during digestion, shrinking down to size after the snake is finished feeding.

Pope says: “The only thing they don’t digest is hair and feathers. Everything else gets completely digested.” They even fully digest bones, thanks to the highly specialized cell that Pope and Lignot recently discovered.

The pit cell, as the researchers dubbed it, is unlike any cell found in any other organism, says Pope. Long and bendy, the pit cell winds to the intestine’s surface, at which point it forms a pit. Inside the pit, tiny spherical bone particles accumulate. The neighboring cells fold their microvilli over the pit, trapping the bone particles for digestion. The purpose of these pit cells, Pope says, is to allow pythons to “digest as much calcium as they can while they are digesting prey.”

New cells are rarely found, according to Pope. Most animals share the same cell types: liver cells, for example aren't much different in a dog versus a human. The pit cell, however, is highly specialized for the python’s unusual eating habits—and with its skinny, winding body, it looks quite unusual. Pope says: “No one has ever seen anything like this before.”

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--Flora Lichtman