Observations on the Behavior and Feeding Mechanisms of the Suctorian Heliophrya erhardi (Rieder) Matthes Preying on Paramecium

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Abstract
The predaceous behavior of Heliophrya and the defensive behavior of various species and strains of Paramecium [P. multimicronucleatum, P. caudatum, P. aurelia] were investigated, using thin plastic film coverslip preparations. Many paramecia contacting the tentacle knob escape, discharging trichocysts at the point of contact. This discharge uproots the cilia attached to the knob. Firmly attached paramecia can escape by rapid turning which twists off the tentacle or a portion of their own solated cytoplasm. Food vacuolar contents of prey were not ingested. EM revealed > 60 slender haptocysts in each tentacular knob which was covered by only the plasma membrane. Dense bodies, some biconcave, were seen inside the nonfeeding knob and tentacular inner tube. Knobs attached to paramecia showed proximally located haptocysts, distally located osmiophilic capped vesicles and dense bodies, and a central core of prey cytoplasm. Contracted tentacles possessed numerous pellicular pores. The inner tube of each tentacle consisted of an outer cylinder of 59 microtubules and an inner cylinder of 22 microtubular groups, each group having 6-9 microtubules in an incurving row. Suctorian food vacuoles varied from large ones containing intact prey organelles, to smaller, denser ones in locations throughout the pellicular layers suggesting egestion.