Sensory Potential and Feeding in Rotifers: Structural and Behavioral Aspects of Diet Selection in Ciliated Zooplankton

Rotifers exhibit a wide range of feeding behaviors which differ in response to changes in nutritional environment or availability of prey. In particular, many suspension-feeding taxa modify food collection when they encounter sestonic particles of differing size, chemical signature, or available density These observations point to a substantial array of mechano- and chemosensory modalities, most of which are based on ciliary structures of the corona and buccal tube. The various cilia, ciliary bundles and cirri are coordinated through a series of nerves and muscles which permit remarkably complicated behaviors when the animals contact individual food cells. Rotifers appear more likely to utilize combined sensory and behavioral functions to accomplish food selectivity than other freshwater zooplankton. However, food cell electivities of the species Brachionus calyciflorus are modified by overall suspended cell density, emphasizing the caution needed when interpreting results of diet selection experiments.