A protozoan (In Greek, ‘protos’ means first and ‘zoan’ means animal) is a single-celled eukaryote. They are included under the kingdom Protista. The study of protozoa is called Protozoology. They are found in ponds, ocean, in moist soil, and in the cells and tissues of plants and animals causing diseases. They range from 2 to 200 microns. Protozoans have specialized organelles. These organelles are used for movement, feeding, and other functions. The types of protozoans are as follows:
Ciliates: Presence of cilia for locomotion.
Flagellates: Presence of flagella for locomotion.
Pseudopods: Presence of pseudopodia for locomotion.
Take one or two drops of hay (In tamil, vaikol) decoction on a slide and observe it under the microscope.
Cell structure of Protozoa
Amoeba is a unicellular microscopic organism. It is found in ponds. Amoeba is irregular in shape. It has cell membrane, cytoplasm and nucleus. It is a protozoan that moves by means of pseudopodia (In Latin, ‘false feet’). Pseudopodia are the extended part of cell membrane. It helps to catch its prey (Algae) . The body flows around the food particle and engulfs it forming food vacuoles. Contractile vacuoles are seen in the cytoplasm that help in excretion. Amoeba reproduces by means of fission and sporulation.