General Characters of Protozoa

Leuwenhoek first described the protozoan animals under a microscope, he called them animalcules. In 1871 Gold fuss gave the name PROTOZOA.

The term protozoa means primitive animals. Protozoans are present from the Precambrian period to recent times 50000 species are included in this Phylum.

General Characters:

1. Protozoa Body: all protozoans are unicellular Hyman called them acellular.
2. Protozoa Symmetry: will show radial symmetry in some organisms, bilateral symmetry in some organisms, and some organisms are asymmetrical.
3. Protozoa may live singly or some are colonial.
4. Protozoa body wall: these animals' body covered by a cell membrane that contains proteins and lipids.
5. Some animals may be covered by Pellicle. Some animals are covered by shells E.g: Elphidium.
6. Protozoa Osomo Regulation: In freshwater animals contractile vacuole is present. It is useful for osmoregulation. in marine and parasitic protozoans, the contractile vacuole is absent.
7. The food vacuole will work as a temporary stomach.
8. Locomotion Protozoa: protozoa animals will show locomotory organelles like flagella. pseudopodia.cilia etc.
9. Nutrition in protozoans is by holozoic, holophytic. saprophytic, coprozoic, etc. Some protozoans are parasites.
10. Respiration is by diffusion
11. Excretion is by diffusion
12. In Protozoa, Asexual Reproduction is by binary fission, multiple fission, budding, etc.
13. In Protozoa, Sexual Reproduction is by syngamy. Conjugation etc.
14. During unfavorable conditions - the protozoa will develop cysts around themselves.
15. In some, the life cycle is complicated with asexual and sexual phases