Abstract
Investigations of the factors that influence the cirral beating of barnacles are important because the survival and growth of barnacles after adhesion and metamorphosis depend on cirral beating. Only while beating their cirri are barnacles able to catch and ingest food, respire, and engage in reproduction and excretion. Although there have been some reports concerning barnacle cirral beating in the laboratory, there have been none with respect to this behavior in the field. The present research concerns the influences of water temperature, salinity, and diatom density on cirral beating in a species of sessile barnacle (Balanus amphitrite) in northern Osaka Bay, Japan. Cirral beating was observed throughout one year except when water temperature fell below 7°C, or salinity below 16.20‰. The frequency of cirral beating rose with rising water temperature but declined as the water cooled. Neither the highest water temperature (32.3°C) nor the highest salinity (32.16‰) observed during this study stopped cirral beating. Water temperature strongly affected the frequency of cirral beating in B. amphitrite, and to a lesser degree so did salinity, but diatom density did not.
