The Passage Time of Prey Through the Digestive Tract of Indo-Pacific Bottlenose Dolphin (Tursiops aduncus)

Abstract

We calculated the passage time of prey with red dye through the digestive tract on captive Tursiops aduncus to accumulate biological knowledge of this species. This study was performed on one captive male dolphin once a day for three consecutive days. The red dye was packed into a capsule made by gelatin. The capsule was then inserted into the prey and fed to the dolphin. Subsequently, the defecation time and color of feces were recorded. We defined initial passage time (IPT) as the period between the time of feeding the dolphin with the red dye-containing prey and the time the red dye was first seen in the feces. Colored feces were observed on all three days of the experiment. The IPT was 254.0 ± 20.4 min (n = 3, Mean ± SD). The average IPT was nearly the same as that of T. truncatus, which belongs to the same genus as that of T. aduncus. In conclusion, it is suggested that T. aduncus defecates a minimum of 4 to 6 hr after feeding. Also, the observation of the normal colored feces suggests that some digesta remains in the digestive tract for 18 to 22 hr.