The trophic role of ciliated protozoans in the functioning of freshwater ecosystems is little known despite the abundance and high reproductive rates of ciliates relative to most aquatic metazoa. By the use of direct and indirect methods, we examined the ability of 9 species of metazoa to prey on Halteria grandinella, a common and abundant planktonic ciliate. Five metazoan species proved capable of capturing the ciliate, despite its 'jumping'escape behaviour. In general, metazoan species described in the literature as 'predaceous' or as filter-feeders on planktonic particles consumed H. grandinella; those described otherwise did not.

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