The influence of prey behaviour on prey selection of the carnivorous plantUtricularia vulgaris

The mechanisms underlying differential prey selection of two microcrustacea ns by the common bladderwort (Utricularia: vulgaris) were studied in the la boratory. Functional response experiments with single prey showed that Utri cularia had a higher attack rate coefficient and a longer handling time coe fficient with the cladoceran Polyphemus pediculus than with the cyclopoid c opepod Eucyclops serrulatus. Observation of predation rate, defined as numb er of prey eaten per unit time, from direct behavioural observation on sing le prey species, showed a higher predation rate with Polyphemus than on Euc yclops, at low prey densities. The opposite pattern was found at high prey density. When the two prey were presented simultaneously to the predator, E ucyclops was preferred over Polyphemus. Results from the situation with two prey and some of the results from the direct behavioural observations supp ort field data on the diet of Utricularia, which shows that cyclopoid copep ods are selected more frequently than Polyphemus.