How does protozoa feed

Ciliates use the fine cilia along their bodies like oars to move rapidly through soil. Protozoa play an important role in mineralizing nutrients, making them available for use by plants and other soil organisms. Protozoa and nematodes have a lower concentration of nitrogen in their cells than the bacteria they eat. The ratio of carbon to nitrogen for protozoa is or much more and to for bacteria. Bacteria eaten by protozoa contain too much nitrogen for the amount of carbon protozoa need.

This usually occurs near the root system of a plant. Bacteria and other organisms rapidly take up most of the ammonium, but some is used by the plant. See figure for explanation of mineralization and immobilzation. Another role that protozoa play is in regulating bacteria populations. When they graze on bacteria, protozoa stimulate growth of the bacterial population and, in turn, decomposition rates and soil aggregation. Infection of Acanthamoeba castellanii by Chlamydia pneumoniae.

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When individuals of opposite mating types meet, the adhere to each other at the oral groove. The micronuclei then divide meiotically, producing four haploid nuclei each. All but one nucleus from each paramecium disintegrate.

The macronucleus also disintegrates, leaving each cell with one haploid micronucleus. These remaining nuclei then divide mitotically and the two cells swap copies of their nuclei. The cells separate and the haploid nuclei fuse, leaving each cell with a new diploid micronucleus. To form a new macronucleus, the micronucleus divides several times and the resulting nuclei develop into a macronucleus. Sarcodina have no flagella or cilia. They move by means of ameboid motion. Helped by filaments of a structural protein called actin, the cytoplasm of these protozoa can flow beneath the cell membrane into new branches called pseudopods, causing the cell to move in a given direction.

Many sarcodina are parasites of the intestinal track and oral cavity of humans and other vertebrates. We are most familiar with the formless genus Ameba seen in , but many sarcodina secrete hard silica- or calcium carbonate-based shells, sometimes in elaborate, species-specific shapes. The way by which protozoa move is so characteristic that it is used to classify them into groups.

Protozoa are a large group of organisms. Their main characteristics are: they are single celled their cells have membrane-bound nuclei we call them eukaryotic they lack a rigid cell wall they usually lack chloroplasts.

Most protozoa are motile.