Predatory behavior of Cupelopagis vorax (Rotifera; Collothecacea; Atrochidae) on protozoan prey

Abstract

By rotating on a short, flexible, pedal stalk, Cupelopagis vorax captures prey that traverse the substratum to which this sessile rotifer attaches . Microvideographic analysis (including slow motion and freeze-frame) permitted us to examine some of the details of Cupelopagis foraging behavior. When undisturbed, Cupelopagis usually faces forward in a resting or neutral position (NP) with its unciliated infundibulum (corona) directed parallel to the surface of the substratum. However, vibrations produced by artificial means (fine pins) or small prey (protists) evoke unique behaviors in Cupelopagis . Our analysis of Cupelopagis foraging on two protozoan prey (Paramecium bursaria and a small, unidentified flagellate, SUF) indicates that this predator possesses a 360 ° encounter field (EF) biased towards the NP Size of the EF appears to be a function of both predator and prey size, but it extends at least 650 µm, as measured from the point of attachment of the predator's pedal stalk to the substratum . When a prey comes close to Cupelopagis, this predator can lean toward the organism, stretching forward on its pedal stalk and extending its corona over the prey in a swift motion (< 0 .5 s) . Probability of capture after attack was a function of prey type (61 .6% for P. bursaria and 41 .5% for the SUF) . Analysis of prey capture by Cupelopagis indicates that this predator has a handling time ranging from a few seconds to several minutes : 24.6 ± 16 .8 s for P. bursaria (n = 274) and 34 .6 ± 25 .4 s for the SUF (n =111) . Occasionally Cupelopagis sweeps part of the EF by retracting its corona, turning to the right or left (mean angle subtended Pz~63 ° ± 42 °), unfolding the corona, and slowly returning to the original resting position . This behavior, termed surveillance, occurs in the presence or absence of prey . While not unique in its ability to detect water movements, Cupelopagis is the only rotifer known to exhibit specific behaviors to vibrations produced by potential prey.

Size-dependent Catalysis of Chlorovirus Population Growth by A Messy Feeding Predator

“…P. bursaria is a widespread protist that may be consumed by several types of aquatic predators, including protists, copepods, nematodes, and planarians [10,14,15,28,29]. We previously showed that interactions between copepods (Eucyclops gracilis) and P. bursaria can generate Chlorovirus blooms though the passage of fecal pellets containing viable zoochlorellae [10].…”

Nestedness in sessile and periphytic rotifer communities: A meta‐analysis

“…In the freshwater littoral, degree of isolation is probably inconsequential at two levels: swamping effects from hatching diapausing embryos and proximity of other plants. However, plant surface (including spatial architecture) is known to be important for both sessile and periphytic rotifers: flat surfaces in Cupelopagis vorax and plant structural complexity in Euchlanis dilatata . Structural complexity also is important for littoral microcrustaceans: (e.g., ).…”

The Collothecidae (Rotifera, Collothecacea) of Thailand, with the description of a new species and an illustrated key to the Southeast Asian fauna

“…We hypothesize that the two groups may have different diets. The latter group probably feeds on free-swimming, planktonic/periphytic organisms, while species of the former group may target browsing animals, in a way that is strikingly similar to Cupelopagis vorax (Leidy, 1857) (Bevington et al 1995). …”