Notes on Protozoa!
Study of Protozoa or Protozoology has a direct bearing on other branches of Zoology. Protozoa occur as single cell and provide excellent materials for the study of the nature and mechanism of cellular activity at unit level. Information accrued from such studies gives a thorough comprehension of biology and Biological principles.
Geneticists have focused their attention on protozoa because the group “presents all problems of heredity and variation in miniature”. The advantage of using protozoa as a genetic material is that it reproduces at a quicker rate and may offer a generation in a day for the study of variation and heredity.
Study of conjugation in Paramoecium has revealed many interesting information about protozoa genetics and the interrelationship between nucleus and cytoplasm in attributing hereditary factors.
Many protozoa live as endoparasites in man and domestic animals and cause diseases. Studies of protozoan parasites thus become an imperative necessity for medical practitioners and veterinarians.
Study of a particular group of protozoa and their hosts helps in realising the geographical condition of the planet earth which existed in remote past. The genus Zelleriella is a parasitic protozoa in the colon of frog. Zelleriella studied from frogs of South America and Australia have been found to be identical.
It is more logical to think that there existed a land connection between Patagonia and Australia through which migration of frogs containing Zelleriella occurred than to think that both the host and parasite have undergone parallel evolution in these two continents.
Parasitic protozoan remains confined to one or more specific hosts. A thorough study of the parasitic forms belonging to one and the same genus helps in establishing or verifying the phylogenetic relationship between the hosts. From the study of the termite protozoa it has been shown that Blattidae and Isoptera are closely related.
For a success in fish culture study of protozoa is essential. Small aquatic organisms as Crustaceans, Annelids and larvae of insects constitute the main bulk of food for the fishes and the organisms on the other hand thrive on protozoa.
Thus the fishes are indirectly dependent upon protozoa and are related to it in the food chain. Myxosporidians are parasites on fishes and are responsible for large-scale fish death. Study of protozoa is thus a must in fishery
Application of protozoa in the bio-control of certain harmful insects is a recent development. Microsporidians infect insect pests such as mosquito and Lepidoptera and heavy infection causes death. Destruction of these insects by pesticides sometimes fails as the insects develop an immunity to the pesticides. For the bio-control of pests attention has now been drawn on protozoa.
Fossil forms of shelled protozoa like Foraminifera and Radiolaria are used in the study of Geology and Palaeontology. Skeletons of Foraminifera occur in many rock strata and the foraminiferous rocks are useful in checking the logs during well-drilling.
Skeletons of Radiolaria have formed many oozes of littoral and deepsea regions and they are also found in silicious rocks. Study of the shells embedded in the rock strata helps in finding out the geological time scale and in petroleum prospecting.