PREDATION BY A PHOTOSYNTHETIC DINOFLAGELLATE GYRODINIUM INSTRIATUM ONLORICATED CILIATES

Feeding of a naked photosynthetic dinoflagellate, Gyrodinium instriatu m, on loricated ciliates was investigated. Gyrodinium instriatum preye d on Favella azorica and Eutintinnus tubulosus by engulfment through t he posterior end of the sulcus. In the case of E.tubulosus, G.instriat um preyed on this small ciliate keeping the original gymnodinioid cell shape. On the other hand, G.instriatum preyed on Favella taraikaensis by absorbing the cell contents of this large ciliate, which resulted in a balloon-like inflation of its body size. It seemed that G.instria tum can change its feeding style according to the size of prey. Thus, the present study shows, by using direct observations on the feeding o f G.instriatum on loricated ciliates, a reversal of energy flow proces ses in the food chain in which photosynthetic organisms eat primary co nsumers. The growth of G.instriatum after feeding on E.taraikaensis an d E.tubulosus is also described briefly.