The feeding and diet of Sagitta tenuis (Chaetognatha) in the Lower Chesapeake Bay

The diet and feeding rates of the chaetognath, Sagitta tenuis, were estimated from laboratory measurements of digestion time and gut content analyses of preserved specimens. Gut clearing times averaged 1.06 h for one prey item and increased with increased number of food items. Copepods were the numerically dominant prey group (92% of diet) and usually occurred as a single item in the gut. During the daytime, 16.3% of the population contained food while at night the proportion increased to 25.3%. Estimated food rations for six size classes of S. tenuis ranged from 3.12 prey chaetognath−1d−1 for4.0–4.9 mm chaetognaths and increase with chaetognath size to 8.7 prey chaetognath−1d−1 for 9.0–9.5 mm chaetognaths. Weight specific rations of dry weight and carbon averaged 0.24 and 0.27, respectively, for the same size groups and decreased with increasing chaetognath size.