Feeding behavior of shallow-water barnacles from the Mediterranean and red seas

Feeding behavior of barnacles may be determined by various factors such as water flow direction, flow velocity, type and location of substratum, predators, systematics, and more. In this study, two shallow-water barnacles from the Red Sea, Amphibalanus (= Balanus) amphitrite and Tetraclita rufotincta, and one from the Mediterranean, Petforatus (= Balanus) perforatus, were examined. Four feeding behavioral parameters were tested under changing conditions of flow direction: cirral fan turning angle, beat duration, beat rate, and percentage of time spent collecting food. When exposed to water, Tetraclita and Amphibalanus collected food vigorously and continuously, regardless of flow direction, while Perforatus perforatus spent far less time and effort collecting food. The differences in feeding behavior may indicate that food is more abundant for the Mediterranean barnacle than it is for the two Red Sea species. The nocturnal behavior of Tetraclita can be attributed to the higher abundance of food particles at night, and/or a diminished risk of predation at night.