PHYLUM: PROTOZOA General Characteristics and Classification By: AAKRITI
Introduction: . Anton Van Leeuwenhoek was the first to observe protozoa (Vorticella convellaria) under a microscope. He called them animalcules. Gold fuss coined the term Protozoa which in Greek means first animals (Proto- first; zoans-animals). . The body of protozoans is unicellular. They are generally referred to as acellular rather than unicellular as the so called single cell performs all the life activities. . Though it is structurally equivalent to a single cell of the metazoan body, it is functionally equivalent to the whole metazoan animals
General Characters of Phylum Protozoa 1.Protozoan animals exhibit protoplasmic grade of organization. There is division of labor among various organelles of the cell 2.These are solitary(Euglena), or colonial (Proteospongia) 3.They may be free living(Amoeba) or symbiotic (Parasitic, mutualistic or commensalistic) 4.Body symmetry is symmetrical (Actinopodeans) or radial (sessile forms) or bilateral (Giardia) or absent (Amoeba)
5.Locomotion is brought about by pseudopodia or flagella or cilia or myonemes 6.Nutrition is holozoic or holophytic or osmotrophic (Saprophytic or parasitic). Digestion is intracellular. Some forms like Euglena are mixotrophic(perform more than one type of nutrition) 7.Exchange of respiratory gases takes place by diffusion through the general body surface. Respiration is anaerobic in some parasitic forms. 8.Excretion occurs by diffusion across general body surface or by contractile vacuoles. Contractile vacuoles serve mainly for Osmoregulation and are common in freshwater forms.
9.Asexual reproduction takes place by binary fission or multiple fission or plasmotomy or budding. 10. Sexual reproduction takes place by syngamy or conjugation 11.Many forms undergo encystment to tide over unfavorable conditions 12.Somotoplasm and germplasm are not differentiated. Hence they are immortal (exempt from natural death).
Classification: . As per one of the classification given out by Hyman, Hickman and Storer, this phylum is divided into two subphyla on the basis of organs of locomotionn * These two subphyla are further divided into S classes Most accepted classification of protozoa is given by BM Honigberg and others based on the scheme given by the committee on Taxonomy and Taxonomioc problems of the society of Protozoologists divides this phyla into 4 subphyla
PHYLUM Protozoa SUBPHYLUM-Sarcomastigophora Sporozoa Cnidospora Ciliophora SUPER CLASS 1. Mastigophora CLASS Phytomastigophora Teleospora Myxosporidea Ciliatea Eg: Myxobolus Eg: Paramoecium Vorticella Balatidium Eg: Euglena, Ceratium, Eg: Monocyctis, Eimera, Noctiluca Plasmodium Zoomastigophora Toxoplasmea Eg: Toxoplasma Microsporidea Eg: Leishmania, Trichomonas, Eg: Nosema bombycis Trypanosoma, Trichonympha 2. Opalinata Haplosporea Eg: Haplosporidium Eg: Opalina, Zelleriella 3. Sarcodina Rhizopodea Eg: Amoebo, Entamoeba, Elphidium Piroplasmea Eg: Babesia Actinopodea Eg: Actinophrys, Collozoum
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