Ingestion of the large pelagic ciliates Stentor araucanus and S. amethystinus by the cyclopoid copepod Mesocyclops araucanus was independent of light conditions and copepod sex, but rates were twice as high on S. araucanus as on S. amethystinus. Copepods consumed 44–183% of their biomass daily. Absorption efficiency was 5–40%, while 20–30% of the ingested food was found in the faeces. In field samples, 32–93% of Mesocyclops had ingested Stentor, indicating the importance of this food source.