Physiology

Pump First, Pay Later

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Science  05 Jan 2001:
Vol. 291, Issue 5501, pp. 15
DOI: 10.1126/science.291.5501.15b

Pythons feed irregularly, with lengthy periods of fasting punctuated by meals that may constitute an appreciable fraction of the animal's own body mass. It has been suggested that the epithelial cells of the small intestine are primed for the extensive digestive process by an initial investment from energy reserves that supports the conversion of a dormant organ into one capable of nutrient absorption and peristalsis.

Starck and Beese have performed histological and sonographic imaging measurements on Burmese pythons fed at intervals over several years. They found that the mucosal lining of the intestine increased three-fold in thickness within 3 days after meals and that this increase was due to fluid-driven expansion of cells and not to cell proliferation. After digestion, new cells were produced, and these apparently shrank (with much shorter microvilli and numerous infoldings of the plasma membrane) to await the next intake of food. The authors suggest that building and investing in a fully functional intestine whilst energy levels are high enables even a starving python to mobilize its digestive system rapidly whenever the next meal appears. — GJC

J. Exp. Biol.204, 325 (2001).

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