Recognition of Prey by Suctoria: The Role of Cilia

ABSTRACT. The interaction between the predator, Discophrya collini , and the prey, Tetrahymena pyriformis , was investigated in order to determine what prey factors(s) may be recognized, facilitating the feeding response of the suctorian predator. When viable, deciliated T. pyriformis were offered to starved D. collini , only 12% of the suctoria captured a ciliate compared to 98% when presented with ciliated T. pyriformis . Starved suctoria were also offered three types of tanned sheep erythrocytes used as artificial prey. After exposure to erythrocytes coated with sonicates of T. pyriformis , 16% of the D. collini displayed one or more attached erythrocytes but after incubation with erythrocytes coated with T. pyriformis cilia, 72% of the suctoria had tentacles with attached cells. No untreated, tanned erythrocytes were captured. When T. pyriformis were treated with ciliary antiserum and then offered to starved D. collini , the resulting capture rate was low (13%), but T. pyriformis treated with normal rabbit serum were captured at a rate comparable to controls (92%). These results suggest that the prey's cilia and/or their surface macromolecules may facilitate prey capture.