Predation by a photosynthetic dinoflagellate Gyrodinium instriatum on loricated ciliates

Abstract

Feeding of a naked photosynthetic dinoflagellate, Gyrodinium instriatum, on loricated ciliates was investigated. Gyrodinium instriatum preyed on Favella azorica and Eutintinnus tubulosus by engulfment through the posterior end of the sulcus. In the case of E. tubulosus, G. instriatum 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 balloonlike inflation of its body size. It seemed that G. instriatum can change its feeding style according to the size of prey. Thus, the present study shows, by using direct observations. On the feeding of G. instriatum on loricated ciliates, a reversal of energy flow processes in the food chain in which photosynthetic organisms eat primary consumers. The growth of G. instriatum after feeding on F. taraikaensis and E. tubulosus is also described briefly.