Predator-induced morphological changes in the ciliate Colpidium (Protozoa, Ciliophora)

Of three tested species of common and well known ciliates, Colpidium kleini and C. colpoda underwent morphological transformation and significantly changed their morphology in the presence of the us ciliate Lembadion bullinum. C. campylum, the smallest tested prey species, did not change. The predator-induced phenotype was significantly broader than the normal one and had an almost spherical shape, as illustrated by the cell width/length ratio, ranging from 0.34 to 0.39 for typical C. kleini and 0.84 to 0.89 for the induced phenotype, depending on the clone. For the two tested clones of C. colpoda the values were 0.48 and 0.52 for the typical form and 0.77 for both transformed phenotypes. Because the total number of somatic kineties in transformed cells did not change, the distance between them almost doubled. Unlike the typical phenotype, kinetosomes in kineties of the induced phenotype were situated very near one another and their total number was significantly higher.