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Protozoan | ||||||||
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The word protozoa means "any of the singled-cell, usually microscopic organisms of the phylum or subkingdom Protozoa, which includes the most primitive forms of animal life." Protozoan comes from the New Latin word Protozoa which was formed by the word proto, which means first, and zoan which means animal. There are about 30,000 species of protozoans identified so far. They are mostly found in water. Some of the types of protozoans are sarcodines, ciliates, flagellates, and sporozoans. An example of a sarcodine is the amoeba. An example of a ciliate is paramecium. An example of a flagellate is trypanosome. An example of a sporozoan is plasmodium. The main structure of a sarcodine is that it uses pseudopods to move. The common sarcodine amoeba is a mass of cytoplasm surrounded by a cell membrane, and has no one shape because they change shape constantly. The structure of ciliates is that it has hundred of short hairs called cilia. The structure of the flagella is that it has long, whiplike structures. Some of the locomotive structures protozoans have are pseudopods, cilia, and flagella. Pseudopods are false feet; projections made of cytoplasm used for locomotion and getting food. Cilia are short, hairlike structures. Flagella are long, whiplike structures. Sporozoans cannot move by themselves, but need help from other things. Protozoans reproduce in many ways. Some reproduce by fission which means two daughter cells are formed from one protozoan. Another way is by sexual reproduction in which may involve fusion of identical or differing gametes. The protozoans attach to each other and exchange nuclei in a process called conjugation. Each nucleus blend together to form a zygote nucleus. Protozoans can be useful and not useful for man. Some cause disease, others do not harm man, and others feed on dead plants and other small protozoans, helping to continue the food chain. Protozoan © 1997 Jacob Eapen. |