Patterns of ciliary currents in Atlantic reef corals and their functional significance

Abstract

Patterns of ciliary currents of 35 species of Atlantic reef corals are described and compared with currents of Pacific corals. Observations were made during the day and at night, during feeding and without food. There is a basic pattern of ciliary currents common to both Atlantic and Pacific species. In all but the family Agaricidae currents flow off the oral disk and up or out between the tentacles. In the centre of the disk region currents flow towards the mouth or the peristome. On the polyp stalk or column there was considerable variation between species in both Atlantic and Pacific forms. In some species currents flow downwards toward the coenosarc while in others, current pass up the stalk towards the tentacles.In the Atlantic Agaricidae there may be an inward flow towards the mouth, an outward flow or a unidirectional flow across the corallum. The patterns of flow depend upon the state of contraction of the polyps or the shape and proximity of adjacent polyps.No ciliary current reversal was observed in Atlantic species. Ciliary currents are functional as a cleansing mechanism and facilitated the ability of mucus nets and strands to gather particles.