(full paper is archived in the Miller Library)
Title: Defecation of the barnacle Balnus glandula in relation to the tidal cycle
Student Author(s): Wood, Stephen G.
Faculty Advisor(s): Abbott, Donald P.
Location: Final Papers Biology 175H
Date: June 1967
Abstract: 1) Balanus glandula produces some feces throughout the tidal cycle except for an eight hour period following termination of feeding at high tide. 2) Submersion increases defecation, and complete emptying of the gut occurs only when animals are at least awash. 3) When kept dry, B. glandula will exhibit almost complete emptying of the gut within 24 hours after the end of the last feeding. 4) The beginning of defecatory activity, approximately eight hours after the end of last feeding, coincides with the onset of lower high water. On some days the barnacles do become awash at lower high water, and experimental submersion of B. glandula at this time can stimulate defecation. This suggests that at least a portion of digestion has been completed by this time, and therefore the filling and emptying of the gut may occur on either a 24 hour or a 12 hour cycle with reasonable efficiency.