Ref ID : 2941
John J. Gilbert and Peter L. Starkweather; Feeding in the rotifer Brachionus calyciflorus III. Direct observations on the effects of food type, food density, change in food type, and starvation on the incidence of pseudotrochal screening. Verh.int.Ver.Limnol. 20:2382-2388, 1978
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B. calyciflorus can prevent particles from entering the buccal field by forming a screen with its pseudotrochal cirri. Pseudotrochal screening rarely occurs under starvation conditions and, except for Euglena, when the concentration of suspended particles is 1 µg ml-1. At particle densities of 100 µg ml-1, the incidence of pseudotrochal screening is a direct function of particle size. For example, screening was observed in 0.07, 0.14, 0.34, 0.45, and 0.55 of the animals in 100 µg ml-1 suspension of Rhodotorula glutinis, Chlamydomonas reinhardti, Ankistrodesmus falcatus, Scenedesmus acuminatus, and Euglena gracilis respectively. The responses of the pseudotrochal cirri to Rhodotorula and Euglena are not simple reflexes and are significantly influenced by previous feeding history, such as whether or not they have been starved or acclimated to the other particle type. These results show the Brachionus, and probably other rotifers as well, do not necessarily ingest food items in proportion to their abundance and can control the admission of particles into their buccal field. This control is a function of particle type and density and can be modified by previous feeding history.