SUMMARY.Campanulate females ofA. sieboldi(clone 12C1) attackAsplanchna brightwelliandA. girodimuch more readily than either the algaVolvox aureusor the rotiferBrachionus calyciflorus. Pre‐feeding campanulates onB. calyciflorusprior to testing does not appreciably affect their response to this prey. Discrimination during feeding occurs immediately after the campanulate's corona contacts a potential food organism and is probably mediated by chemoreceptors. Once a food organism is attacked, the probabilities of it being captured and subsequently swallowed are high and similar for each of the four organisms tested.Since food organisms other thanAsplanchna. such asV. aureusandB. calyciflorus, induce campanulates in this clone to produce cruciform, and thus frequently sexual, females in succeeding generations, a tendency of these campanulates to select congeneric prey would favour the maintenance of the campanulate morphotype and thus the continuation of parthenogenetic reproduction in the ensuing populatio