protozoa - characteristics and classification - harmful and beneficial protozoans

1. by,
K.ThangaMallika
I M.Sc., Microbiology

2. PROTOZOA
 Protozoa are a diverse group of unicellular eukaryotic
organisms.
 The word “protozoa” by coined by GEORG AUGUST
GOLDFUSS in 1818.
 They are heterotrophic organisms and they donot
have chlorophyll.
eg: Amoeba, paramecium, euglena.

4. CHARACTERISTICS
 A protozoan body consists of only mass of
protoplasm, so they are called acellular or non-cellular
animals.
 HABITAT - mostly aquatic, either free living or
parasitic.
 SIZE - most protozoans are in the size of 1 to 10
micrometer long, but Balantidium coli may measure
150 micrometer.

5.  BODY- body of protozoa is either naked or covered by a
pellicle.
 LOCOMOTION- locomotary organ are pseudopodia or cilia
or absent.
 NUTRITION - nutrition are holophytic (like plant) or
holozoic (like animal) or saprophytic or parasitic.
 DIGESTION - digestion is intracellular, occurs in food
vacoules.

6.  RESPIRATION - respiration occurs through the body
surface.
 OSMOREGULATION – contractile vacoules helps in
osmoregulation.
 In most protozoa, the cytoplasm is differentiated into
ectoplasm (the outer, transparent layer) and endoplasm
(the inner layer containing organelles).
 The structure of cytoplasm is mostly seen in species with
projecting pseudopodia, such as amoebas.

7.  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.

8. CLASSIFICATION OF PROTOZOA

9. 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.

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

11. RHIZOPODA
 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. ZOOMASTIGOPHORA
 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.

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

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

15.  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.
 Scientific study - Many protozoa are used in biological and
medical researches.

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