The potential of copepods as predators of free-living nematodes was tested by presenting Diacyclops bicuspidatus
, a common Holarctic cyclopoid copepod, with Panagrolaimus sp.
as prey in the laboratory. D. bicuspidatus
readily fed on nematodes of all size classes, including prey longer than itself. No size preference was observed. Handling times varied between a few seconds and several minutes, depending on the size of the prey. At different prey densities, the feeding rates of D. bicuspidatus
followed a type II functional response. Starved D. bicuspidatus
consumed up to 45.1 nematodes in 2 h, that is, 43.5% of the copepod’s body mass. Indications that nematophagous nutrition is common among freshwater copepods are discussed.