Filtration of Phytoplankton by the Octocoral Alcyonium digitatum L.

Abstract

MOST of the work carried out on the food and feeding of cœlenterates deals with the true reef-building corals, Actiniae and Scyphomedusae, which harbour zooxanthellae in their tissues. The group Alcyonaria, however, has received less attention. There seems to be considerable controversy as concerns the significance of these symbiotic algae for their host-cœlenterates. Some authors report that the cœlenterates derive no benefit from their zooxanthellae^1,2, while others believe that zooxanthellae form a considerable part of their food, the other part being of animal origin^3–5. Still others maintain that some cœlenterates, namely the xeniid octocorals, may in some way or other rely on their algae as their only source of food^6,7.