Provide Foods

• There are several protozoa which directly or indirectly supply foods to man, fish, & other animals.
• The aquatic protozoans provide food to the larvae of aquatic insects.
• There are several protozoa, which are sinks to the bottom of the ocean after death, and forms food material for deep-sea fauna. Such an Example is, Pelagic protozoan like foraminifera and Radiolaria.

 Helpful in Sanitation

• There are several protozoa which live in polluted water and get organic matter as their food material and thus help to purify it.
• Many protozoa feed upon bacteria and play a vital part in the sanitary betterment and retaining water safe for drinking.

Symbiotic Protozoa

There are several symbiotic protozoa which lives within the gut of termite such as Trichonympha and Colonymphya etc. They digest the cellulose which is utilized by the host cell.

Control of insect

There are other protozoa which prevent harmful insects by persisting their bodies.

Commercial use/Industry

Skeleton of dead protozoa (Foraminifera and Radiolaria) immerse in sea & create oceanic ooze at the bottom part of ocean. These are solidified & covert into rock strata. Some of them are used as a filtering agent or used to make chalk and still, others are utilized for abrasives.

Building Material

The skeleton of protozoa which are getting deposits at the sea bottom they converted into the limestone rock over time. These limestones are used as Building Material. A common example of protozoa is Comerina which helps in the formation of limestone.

Oil Exploration

Skeletone of various protozoa often found in association with oil deposits. Such an example is the skeleton of Foraminifera and Radiolaria. Thus they help to find the exact location of oil.

Scientific Study

For the minute size and quick reproduction of protozoa, geneticists use them in laboratories to study the heredity and variations. Some of them also used in biological and medical researches. Such an example is; Tetrachymena geleii is used in nutritional research to check the effects of various foods and poison.

Harmful Protozoa

All the harmful or parasitic protozoa are found in plants, animals including man and responsible for various infectious diseases. These are harmful as well as useful species.

Pollution of Water

Some protozoa are important in water disinfection, while others are engaged in water contamination or pollution. The protozoa of fecal source refer to this category. Some free-living protozoa such as Uroglenopsis, also contaminate water by creating pungent and oily secretions with offensive odors, which provide unfit water for human consumption.

The free-living protozoa multiply in natural drinking water and make them unpalatable. An example of this type of protozoa is, Uroglenopsis which responsible for flashy odor like that of cod- liver oil. Peridinium release a smell which is resembling that of clam-shells.

Soil Protozoa

The soil contain different types of species of protozoa, which are feed upon the nitrifying bacteria. Thus they decrease their activity as well as decrease the concentration of nitrogen in soil which is given the nitrifying bacteria.

Destruction of Animals of Food Value

The excessive growth of dinoflagellates such as Noctiluca and Gonyaulax turns the ocean water red with their bodies. As a result, they perform a toxic reaction with the molluscs like clam oysters and mussels and make them unfit for eating by human beings.

Destruction of Wooden Articles

The termite’s gut contains some flagellates such as Trichonympha and Colonympha, which help them to digest the cellulose material. In absence of these flagellates termites will die or change their diet. Therefore, these indirectly influence the distraction of wooden articles and books.

Parasitic Protozoa

Parasitism is a relationship between two organisms where one organism lives at the expense of the other giving nothing in return. The first one termed as parasite and the other one known as host, on which the parasite lives.

There are present two types of parasites on the basis of their survival technique such as Facultative parasites, which can live for a long time without the host. The second one is obligatory parasites, these are cannot survive when separated from their host.

Pathogenic Protozoa

Those protozoa responsible for infectious disease are known as Pathogenic Protozoa. There are different class of pathogenic protozoa such as;

• Pathogenic Sarcodines: These are can be found in intestine of man and other animals and responsible for different diseases. There are two species of Entamoeba such as E. histolytica found in man and other mammals and the second one is E. invadens which is found in reptiles. These are cause serious infection. E. histolytica casue amoebic dysentery or amoeliasis in man.
• Pathogenic flagellates: Some examples of Pathogenic flagellates are genera Leishmania, Trypanosoma, Histomonas, Trichomonas, and Giardia. Leishmania is responsible for Kala-azar while L. braziliensis responsible for infection of nasopharynx and skin lesion. Trypanosoma also responsible for serious diseases in mammals  i.e. fatal African sleeping sickness. Trichomonas is responsible for vaginal trichomoniasis or vaginitis in human females. T. foetus causes trichomoniasis of cattle
• Pathogenic Sporozoans:  Some examples of pathogenic sporozoans are Plasmodium, Eimeria, Isopora, and Babesia. The four species of Plasmodium is responsible for malaria in man. Eimeria is the causative agent coccidiosis in chickens and rabbits. E. canis in dogs, E. felina in cats, E. bovis in cattle and E. intricate in sheep and goats. Isospora lives in intestine of man and other animals. The pathogenic species of Babesia responsible for lethal haemoglobinuric fever, redwater fever or Texas fever in cattle (Babesia bigemina). B. equi in horses, B. rodhani in rodents, B. felis in cats, B. motasi in goats, cause malignant jaundice, anemia, and fever in their specific hosts.
• Pathogenic Ciliates: An important example of Pathogenic Ciliates is Balantidium coli which can be found in the intestine of man and often in frogs.

Types of Parasite

Based on the type and level of intimacy and the location of the parasites on their host cell, they are classified into two groups such as;

1. Ectoparasites
2. Endoparasites

Ectoparasites

Ectoparasites are live on the surface of the host cell. There are different types of Ectoparasites such as;

• Hydramoeba hydroxena found on epidermis of Hydra.
• Costa necatrix found in the epidermal cells of fishes and Ichthyophthirius multi files.

Endoparasites

These types of parasites are live within the host body. There are present different types of Endoparasites which are classified based on their location;

• Coelozoic: These are in the lives alimentary canal or cavities of the host body.  Example: Entamoeba histolytica, Giardia lamblia, Balantidium coli, etc.
• Histozok: These are occupies space between the host cells. Example: Trypanosoma gambiens lives in the blood plasma of vertebrates.
• Cytozoic: Cytozoic lives within the host’s cell. Example: Plasmodium and Babesia live within the blood cells of hosts. Sarcocystis lives within the striped muscles of a host.

Parasitic Protozoa Mode of Infection

There are differetn way by which parasitic protozoa reach new hosts such as;