Protozoa are unicellular eukaryotic microorganisms, predominantly free-living and found in water and soil, with a significant diversity of around 65,000 species. They can be classified into four main types based on motility: flagellates, ciliates, sarcodina, and sporozoa, and they reproduce both sexually and asexually. While some protozoa are beneficial for food chains, sanitation, and scientific research, others can be harmful by contaminating water and reducing soil fertility.

1. General Characteristics of
Protozoa
Dr. Rachana Choudhary
Asst. Prof. Department of Microbiology
Shri Shankaracharya Mahavidyalaya Junwani, Bhilai

2. INTRODUCTION
The word protozoa is come from Greek
protozoon word meaning “FirstAnimal”.
The word “protozoa” first coined by GEORG
AUGUST GOLDFUSS in 1818.
Protozoa are unicellular (may be Multicellular)
Eukaryotic microorganism.
It constitute a large group of about 65,000 species.
Most of which are harmless free living and
inhabits water and soil.

3. CHARACTERISTICS
Mostly Unicellular organism with fully functional
cell
Aquatic , free -living, may be parasitic or symbiotic.
They are heterotrophic organisms and they do not
have chlorophyll.
They are motile have locomotive organelles.E.g.
Flagella and Cilia for movement
eg: Amoeba, Paramecium, Euglena.

4. MORPHOLOGY (SIZE)
The size of Protozoa is range between 3 to 300
micrometer.
Few ciliate and Amoeba are larger enough to be seen
with naked eyes (they are about 4 to 5mm).
Except Sporozoates, all types of protozoa are motile
either through Flagella, cilia orPseudopodia
Have Eyespot that can detect change inlight.
Respond to light & learn by trial & error

5. MORPHOLOGY
Protozoa are Eukaryotic resemble to animal cell,
contain major cell organelles (including Nucleus,
Mitochondria)
Their organelles are highly specialized for feeding,
reproduction and movement
The cytoplasm of protozoa are divided into an outer
layer called Ectoplasm and an inner layer called
Endoplasm

6. Morphology
Ectoplasm helps in movement, feeding and Protection
Endoplasm houses Nucleus, mitochondria and food
Some protozoa have special appendages Flagella and
cilia that helps in theirmovements
Freshwater protozoa have contractile vacuolesto
pump out excesswater
Their shape may remain constant (specially in Ciliates)
or change constantly (as seen inAmoeba)

7. NUTRITION
Mostly protozoa feed on dead plants and animal debris
while some (trophozoites) feed on bacteria andAlgae.
Parasitic Protozoa feeds on the fluids and tissues of
their host(e.g. Plasma and blood cells)
Some Protozoa live in symbiotic relationship with
other plants andanimals

8. Classification of Protozoa
Protozoa are classified on the basis of their motility
and method of reproduction
They are classified into Four maintypes
Flagellates
Ciliates
Sarcodina
Sporozoa

9. Flagellates
• It is characterised by one
or more flagella
Free living or parasite.
Body covered with
cellulose, chitin or silica.
Sexual reproduction
occurs by longitudinal
fission.
Examples: Trypnosoma.

10. Ciliates
Complex freshwater
or saltwater
protozoan.
It swims by the coordinated
beating of their cilia.
Nuclei is of two
types: micronucleus
& macronucleus.
Body is covered by pellicle.
Examples:
Paramecium, Voricella.

11. Sarcodina
These are amoeboid
organisms that produce false
pseudopodia.
It preys on fungi , other
protists and small
invertebrates.
Reporduction by means of
sexual and asexual.
Mostly free living, some are
parasitic.
Examples:Amoeba
, Entamoeba.

12. Sporozoa
Commonly parasitic on
vertebrate animals.
Locomotory organ and
contractile vacuoles are
absent.
Body covered with pellicle.
Exclusively endoparasites.
Reproduction by means of
asexual and sexual.
Examples: Plasmodium,
Monocystis.

13. REPRODUCTION
Reproduction occurs by both sexual and asexual
reproduction.
Asexual - usually by binary fission.
Sexual - happens by Conjugation .
NUCLEUS - Nucleus may be compact with diffuse
chromatin or vesicular with central or eccentric
karyosome (DNA) and peripheral chromatin (RNA).
RESPIRATION–respiration is mostly anaerobic.

14. ECONOMIC IMPORTANCE OF
PROTOZOA
Protozoans are classified into two types based
on their activities.
 Harmful protozoa
 Beneficial protozoa

15. BENEFICIAL PROTOZOA
1. Food - Protozoa provide food for insect larvae and
worms, which are taken by fishes and crabs and which
are eated by man.
2. Insect control - Several protozoa control harmful
insects by persisting their bodies.
3. Helpful in Sanitation - A large number of protozoa living
in polluted water feed upon organic matters and thus
purify it.

16. 4.Oil exploration - Petroleum is organic origin.The
skeletal deposit of Forminifera and Radiolaria are
often found in association with oil deposits.In this
means, they help in the exact location of oil.
5. Scientific study - Many protozoa are used in
biological and medical researches.

17. HARMFUL PROTOZOA
1. Pollution of water - Drinking water in natural
condition is made unpalatable by the reproduction of
some free living protozoa in it.
2. Destruction of wooden articles - Some flagellater like
Trichonympha & Colonympha live in the gut of
termites and help in cellular digestion.
3. Reduction in Fertility of soil - Protozoans feed on
nitrogen fixing bacteria thus reduce the fertility ofsoil.

18. Conclusion
Protozoa are single-celled eukaryotes (organisms whose
cells have nuclei) that commonly show characteristics
usually associated with animals, most notably mobility
and heterotrophy.

19. References
• General Microbiology by R.P. Singh
• Microbiology by Dubey & Maheshwari
• Google search
• SlideShare

20. Thank you