The defensive function of trichocysts in Paramecium tetraurelia against metazoan predators compared with the chemical defense of two species of toxin containing ciliates

The time-honored assumption about defensive function of trichocysts in Paramecium against predators was recently verified experimentally against different species of unicellular predators. In this work we examined the defensive function of trichocyst for three metazoan predators, Cephalodella sp. (Rotifera), Eucypris sp. (Arthropoda) and Stenostomum sphagnetorum (Platyhelminthes). The results showed the defensive function of trichocysts against two of these metazoan predators (Cephalodella sp. and Eucypris sp.) while they seem ineffective against S. sphagnetorum. We also compared the defensive efficiency of the trichocysts of P. tetraurelia with that of toxin-containing extrusomes of two ciliates.