Predation by a photosynthetic dinoflagellate Gyrodinium instriatum on loricated ciliates

Feeding of a naked photosynthetic dinoflagellate, Gyrodiniuminstriatum, on loricated ciliates was investigated. Gyrodiniuminstriatum preyed on Favella azorica and Eutintinnus tubulosusby engulfment through the posterior end of the sulcus. In thecase of E.tubulosus, G.instriatum preyed on this small ciliatekeeping the original gymnodinioid cell shape. On the other hand,G.instriatum preyed on Favella taraikaensis by absorbing thecell contents of this large ciliate, which resulted in a balloonlike inflation of its body size. It seemed that G.instriatumcan change its feeding style according to the size of prey.Thus, the present study shows, by using direct observationson the feeding of G.instriatum on loricated ciliates, a reversalof energy flow processes in the food chain in which photosyntheticorganisms eat primary consumers. The growth of G.instriatumafter feeding on F.taraikaensis and E.tubulosus is also describedbriefly.