Abstract
The feeding of Sagitta nagae, the most predominant chaetognath species in Suruga Bay, was studied. Specimens were collected with ORI-100 net (1.0mm in mesh aperture) and MTD net (0.35mm in mesh aperture) and were fixed with neutralized formalin. The main food organisms ofSagitta nagaewere the copepods, Candacia bipinnata, Calanus pacificus and Pareuchaeta russelli. The food-containing ratio (PIT, %) was higher at night and lower in the daytime. Here, P is the number of Sagitta containing food organisms in the gut and T is the total number of Sagitta examined. P/T was almost constant vertically in the upper 100m layer. P/T was generally influenced neither by food density nor by the copepod numbers per Sagitta in this study. Sagitta nagae took food throughout life. Food ingested by Sagitta per day was calculated as 37.6% of Sagitta in dry weight.
