Definition: Microscopic, eukaryotic unicellular organism commonly motile heterotrophic having one or more nuclei called protozoa.
General Characteristics:
1)Habitat: Protozoans exhibit mainly two forms of life: Free living (aquatic) and parasitic (ecto-endo parasite).
2) Cell size: The body is microscopic and unicellular.
3) Type: They are the simplest and most primitive of all animals.
4) Organisation: They have protoplasmic grade of organisation
5) Body form: Either solitary or colonial.
6) Symmetry: Body symmetry is either none or bilateral or radial or spherical.
7) Protoplasm: Body protoplasm is differentiated into an outer ectoplasm and inner endoplasm.
8) Locomotory Organ. They have fingers like prejection pseudopodia; whiplike flagella; or hair like cilia or none.
9) Nutrition: Nutrition may be holozoic (animal like), holotype (plant like), saprozoic or parasitic.
10) Respiration: They respirate through the body surface by diffusion.
11) Reproduction: Asexual Reproduction (binary/multiple fission; budding, Sporulation) and Sexual Reproduction (Conjugation, Syngany).
Example: Amoeba, Euglena, Opalina, Labyrinthula, Plasmodium, Monocystis, Nosema, Telomyna, Paramyxa, Haplosporidium, Myxobolus, Myxodium, Paramoecium.
Sub Kingdom-Protozoa (Levine et al 1981)
- (i) Sarcomastigophora
- (ii) Labyrinthomorpha
- (iii) Apicomplexa
- (iv) Microspora
- (v) Ascetospora
- (vi) Myxozoa
- (vii) Ciliophora
(i) Sarcomastigophora:)
Characteristics:
1)Body: Organisms of this phylum are unicellular on colonial.
2) Locomotory Organ: Locomotion done by pseudopodia flagella or both.
3) Nucleus: Nucleus is of one type, except in heterokaryotic Foraminifera.
4) Reproduction: They reproduce by both asenual and sexual method.
5) Nutrition: They are autotrophic, saprozoic or heterotrophic.
Example: Amoeba sp., Euglena sp., Opalina sp. etc.
(ii) Labyrinthomorpha 🙂
Characteristics:
1) Body Shape: They are spindle shaped, non-amoeboid cells.
2) Locomotion: They locomote from one place to another by gliding movement on the mucous tract.
3) Nutrition: They are saprozoic or parasitic on algae & seagrass.
4) Spores: Zoospores are produced by most species.
Example: Labyrinthula sp.; Labyrinthomorpha sp. etc.
(iii)Apicomplexa 🙂
General Characteristics
1)Habitat: All species are parasitic in nature.
2) Apical Complex: Anterior part of the body forms apical complex to penetrate/hold the host cells.
3) Polar rings: Apical complexes are made up of polar rings.
4) Locomotion: Locomotory organelles are absent.
5) Reproduction: They have both Asexual phase [Schizogony, Sporogony] and Sexual phase [Gametogony] for reproduction.
6) Spores: They produce spores called microspores at some stage, so they are also called sporozoa.
Example: Plasmodium sp., Monocystis sp. etc.
(iv) Microspora🙂
General Characteristics:
1)Body: Spores are unicellular, obligate intracellular parasites.
2) Spore: Spores are the only stage of the life cycle capable of existing outside the host and in infective stage.
3) Reproduction: They reproduce in the host by producing spores (sporogony).
4) Layer of Spores: Spores surrounded by thick double layers called cyst wall. Outer layer: Exospore (proteinaccons) and inner layer: Endospore (Chitinous)
5) Polar tube: They have polar tubes and polar caps in spores.
6) Mitochondria: Mitochondria absent. They have mitosomes.
Sporoplasm,
7) Sporoplasm: They are uninucleate or binucleate.
Example: Nasema sp., Telomyxa sp. etc
(v) Ascetospora🙂
General Characteristics:
1)Spores: Most of cases spores are multicellular.
2) Sporoplasm: Spares with one or more sporoplasm.
3) Habitat: They are intracellular parasites.
4) Polar capsules: Spores without polar capsules or polar filament
Example: Paramyxa sp.; Haplosporidium sp. etc.
(vi) Myxozoa🙂
General Characteristics:
1)Habitat: They are endoparasites.
2) Spores: They reproduce by multicellular spores.
3) Sporoplasm: They have one sporoplasm.
4) Polar capsules: They have one or more polar capsules.
5) Valves: Each spore with 1,2 or 3 (rarly more) valves.
Example: Myxobolus sp., Myxidium sp.
(vii) Ciliophora:)
General Characteristics:
1)Habitat: They are found in freshwater- ponds, rivers, and damp soil.
2) Locomotion: Locomotory organ of this phylum is cilia (hair-like).
3) Nucleus: Nucleus are of two types – Macro & micro nucleus.
4) Reproduction: Reproduction done by Asexual (Transverse fission) or Sexual (Conjugation) method.
5) Nutrition: They are heterotrophic [free living / Parasite]
6) Vacuole: Presence of Contractile vacuole.
Example: Paramoecium sp., Tetrahymena sp.; Balantidium sp. etc.