An analysis of the feeding behavior of Daphnia pulex 1

The feeding abilities of Daphnia pulex were investigated by offering it suspensions of the small alga Chlamydomonas minutissima and its larger congener Chlamydomonas capensis. The suspensions differed in the relative abundance of the two algae and in th e presence or absence of intermediately sized latex spheres. The experiments were designed to distinguish between mechanistic and behavioral modes of feeding. Daphnia showed marked flexibility in its feeding patterns, consistent with the behavioral hypothesis. It preferred to feed on C. minutissima. Significant feeding on C. capensis occurred only when C. capensis ‐conditioned animals were presented suspensions relatively low in C. minutissima or in the presence of latex spheres. Analysis of gut contents revealed a reduction in the ingestion of latex spheres over time. Total carbon and life history analyses suggest that the preferred food, C. minutissima, is the superior food as well.