THE DIGESTIVE STRATEGY OF THE COMMON MARMOSET, CALLITHRIX-JACCHUS

Digestive tract morphology and function were studied in the common mar moset (Callithrix jacchus), a small (350 g) exudivore with a well deve loped caecum. Transit times (times of first appearance of the markers in the faeces following a pulse dose in the food) were similar for Co- EDTA, which marks the fluid phase of the digesta, and Cr-mordanted cel l walls, which marked the large (600-1200 mu m) particulate phase of t he digesta. However, mean retention time (the average time taken for t he markers to transverse the whole digestive tract) for Co-EDTA was si gnificantly longer than for Cr-cell walls, indicating selective retent ion of fluid digesta relative to large particles, probably in the caec um. These data are consistent with a digestive strategy of the common marmoset that appears to be based on rapid digestion of higher quality foods (animal prey, fruits) in the small intestine, followed by micro bial fermentation of the complex polysaccharides of plant exudates in the caecum, which would allow for considerable dietary flexibility in its natural habitat of scrub forests.