Protozoa

Protozoa are on-celled eukaryotic organsims that mostly feed on bacteria and small particulate nutrients. They are classified by their means of motility. Protozoa reproduce asexually by fission, budding, or schizogony. Schizogony involves the fission of the nucleus prior to cell division. Some protozoa produce gametes or gametocytes-haploid sex cells that fuse to form a zygote. Most protozoa are aerobic heterotrophs, but most intestinal protozoa are capable of anaerobic metabolism. A few, like Euglena, contain chlorophyll and are photoautotrophs. Some protozoa absorb food through the cell membrane, but many have a coating, the pellicle, that does not allow them to do so. Amoebas engulf food and phagocytize it. Digestion in all protozoa takes place in the vacuoles, and waste is eliminated through a pore. BD, Nikon, and Axygen supply products used in protozoa research.