Protozoa are single-celled microscopic organism. Protozoa are heterotrophs i.e they don’t produce their own food. They generally feed on organic matter such as other microorganisms or organic tissues and debris. Protozoa are heterotrophic microorganisms which do not fully plant or animals.
Why protozoa were considered animals?
Protozoa are unicellular microorganisms which do not fully dissemble plant or animals. The word Protozoa means “early animals” . Earlier Protozoa were consider as animals as they do not have cell wall and they can move. Apart from few examples of protozoa which contains chlorophyll are either saprophytic and parasitic. the protozoa which contains chlorophyll lack other plant characters.
Habitat of protozoa
protozoa freshwater, saline water, ponds , lakes, dirty water drains, rivers, sea water and also in damp soil. Some parasitic protozoa so live in the bodies of other organisms including human beings. Examples of protozoa Giardia, Amoeba, Paramecium, euglena etc.
The most important characteristic of protozoa is that they can move from one place to another.
Examples
Amoeba:- Amoeba is a single cell organism looks like mass of Protoplasm with no fixed shape. It can move in any direction by extending pseudopodia. Pseudopodia is also called as false feet. A pseudo podium is formed by the flow of Protoplasm in the direction of movement. Pseudopodia helps Amoeba in feeding. It extends to encircle the food particle which is then taken in by the cell and digested. Amoeba feeds tiny algae and bacteria.
Paramoecium
This slipper shaped protozoan which lives in ponds and ditches swims by beating it’s Cilia against water. Movement of Cilia helps to direct food and water into an oral groove in paramoecium. Paramecium feeds on small algae and bacteria. Waste matter of paramoecium is thrown out through an anal pore.
Euglena is found in ponds, ditches and other stagnant water bodies.
The body of euglena is spindle shaped slightly elongated and tapers at the top.One end of euglena has flagellum which they use to move from one place to another. Some euglena has two flagella. Euglena with chlorophyll normally obtain their food through photosynthesis. Euglena which lives in dark condition ingest food particles through a mouth like opening leading to a gullet. This organism has characteristics of both plants and animals. Euglena contains chlorophyll and that’s why most of them autotrophs. Even euglena has chlorophyll and live as autotroph it doesn’t come under plant Kingdom because they don’t have cell wall. Some euglena don’t have chlorophyll and live as saprophytes or parasites.
Advantages of protozoa
Saprophytic protozoans benefit the environment by decomposing organic matter in the soil. Parasitic protozoans prey on bacteria and algae helps to regulate the population of bacteria and algae.
Many protozoa are parasites and causes many diseases.
Diseases like dysentery and malaria are caused by protozoa. For example entamoeba causes amoebic dysentery.
Protozoan name plasmodium causes disease malaria inhumans. Plasmodium is commonly known as malarial parasite.
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