The use of soil biofilms for observing protozoan movement and feeding

Protozoan movement and feeding regimes in soil biofilms were observed with inverted microscopes and Utermöhl plankton counting chambers (4 mm deep). In a new use for these counting chambers, the three-dimensional appearance of a soil pore network can be simulated using long working distance objectives (40×). Protozoa were often associated with soil surfaces and penetrated soil crevices of less than 3 μm in diameter by either distorting their body outlines or with slender pseudopodia of less than 2 μm at the tips. Many ciliates repeatedly collided with soil particles and released attached bacteria into the soil solution for subsequent predation.