MEAL SIZE AND SPECIFIC DYNAMIC ACTION IN THE RATTLESNAKE CROTALUS-DURISSUS (SERPENTES, VIPERIDAE)

We studied the effect of meal size on specific dynamic action (SDA) in the South American rattlesnake Crotalus durissus, by measuring oxygen consumption rates (VO2) prior to and after the ingestion of meals ran ging from 10-50% of snake's body mass. Regardless of meal size, variat ion in VO2 with time during digestion demonstrated the same general pa ttern. Oxygen consumption rates peaked between 15 and 33 h post-feedin g, at values 3.7-7.3 times those prior to feeding. Snakes, while diges ting meals of 30% and 50% of their body mass, experienced VO2 that exc eeded rates measured during forced activity. Following peaks in VO2, r ates returned to prefeeding values within 62-170 h post-feeding. Post- prandial peak in VO2 and the duration of the metabolic response to fee ding increased with meal size. Digestion is an energetically demanding activity for C. durissus, with an estimated cost equaling 12-18% of t he ingested assimilated energy.