Observations on the susceptibility of some protists and rotifers to predation by asplanchna girodi

Direct observations of behavioral interactions show that the predator A. girodi: 1) easily ingested Synchaeta pectinata, two forms of Keratella cochlearis cochlearis, and individuals of Conochilus unicornis and C. dossuarius enzymatically dissociated from their matrix; 2) rarely, if ever, captured Kellicottia bostoniensis and intact Conochilus; and 3) generally rejected the peritrich ciliate Rhabdostyla sp. and the dinoflagellate Peridinium sp. Coloniality and secretion of a gelatinous matrix in Conochilus can be viewed as adaptations to limit mortality from invertebrate predation. Intraspecific variability in the feeding responses of A. girodi is considered.