1. Protozoa is a diverse group of unicellular eukaryotic organisms that includes free-living, parasitic and mutualistic forms. They exhibit different modes of nutrition and locomotion. 2. Historically, protozoa included many disparate groups but is now defined as unicellular organisms with sometimes colonial or multicellular stages. They lack specialized tissues and organs. 3. Major protozoan groups include the SAR supergroup containing amoebas, flagellates and foraminifera, as well as ciliates, apicomplexans, microsporidians and others. Many are important as parasites, in nutrient cycling or in forming structures like coral reefs

1. 1
The Protozoans

2. Historical Background
2
Historically Protozoa
included nearly
every group known
as ‘Protista”- fungus
like, animal-like,
plantlike, and other
unicellular group.
Protozoa means ‘first
animals’, coined by
Goldfuss (1820)

3. Historical Background
3
Early biologists considered this group as the ancestors of metazoans
among the free-living protists
Specialized in sub
cellular/biochemical level
Specialized in cellular level
Specialized in tissue level

4. Kingdom Protozoa
4

5. Kingdom Protozoa
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6. 6
Dicyemida
(Rhombozoa)
Orthonectida

7. 7

8. It is now an established taxon
including….
8
Collared flagellates
(Choanoflagellates),
the sister taxon of
metazoa and truly
qualifies the ‘first
animals’.

9. Taxonomic relationship
9
Remarkably Myxozoans
exhibit similarities with
cnidarians (anemones &
jellyfish)
Thus, protozoa is the
name for grade within a
scheme of organization, a
loose confederation of
eukaryotic taxa, rather
than a monophylatic
taxon

10. A descriptive account
 Nearly 215,000 species equal
in no the vascular plants and
10 times more plentiful than
bacterial & viral species
combined.
 Protozoan parasites have
enormous impact on
humans, poultry, fish, wild
animals.
 Mutualism: photosynthetic
protozoa & corals – forming
coral reef.
 Myriads- in soil & water –
essential role in food chain.
10

11. Soil Protozoa
Kingdom Protozoa
11

12. Volvox : a very good missing link
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13. Many are colonial….
13
Body: A single cell
Cell size: ranges form
10 μm, as in
choanoflagellates, to
several cm in some
dinoflagellates, forams
& amoeabe
Vorticella colony

14. Structural Organization
14

15. Structural Organization
15

16. Therefore….
 They are unicellular with some colonial and
multicellular stages.
 Most are microscopic.
 All symmetries are present within members
of the group.
 No germ layers
 No organs or tissues are formed, but
specialized organelles serve many of these
functions
16

17. Exo or endoskeleton
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Protozoan skeleton,
like metazoans, can
be both endo & exo
skeletons.
It forms a complete
covering, called as a
test
(or lorica/theca/shell)
Star sands:
Foraminiferans

18. 18

19. Kingdom Protozoa
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20. 20

21. 21
This is how it moves

22. Thus…..
 They include free-living, mutualistic, commensal and
parasitic forms… may be aquatic or terrestrial
 They move by pseudopodia, flagella, cilia and they
can direct cell movements.
 Most are naked, but some have a simple
endoskeleton or exoskeleton.
 All types of nutrition are present: autotrophic,
heterotrophic and saprozoic.
22

23. 23

24. 24
Adaptability
 Protozoans are ecologically important primary
producers, consumers and as vital links in the
food chain
 Humans are greatly effected by parasitic
protozoans either directly or indirectly
– Effects range from irritating - fatal
 Malaria (Plasmodium spp.) worldwide epidemic

25. 25
Reproduction
 Asexual reproduction
– Replication of chromosomes and the splitting of the
parent into two or more parts
– Binary fission
– Multiple fission
– Budding
 Protozoans are problematic in their
associations as colonial forms

26. Binary Fission: Amoeba
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27. Multiple Fission in Amoeba
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28. Kingdom Protozoa
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29. 29

30. Biological Contributions in
 Protozoa have intracellular specialization or
organization of organelles in cells.
 Cells may have distinct functions; some colonial
protozoa have separate somatic and reproductive
zooids.
 Asexual reproduction occurs by mitotic division.
 Some have true sexual reproduction with zygote
formation.
30

31. Biological Contributions in
 Responses to stimuli represent the simplest
reflexes and inborn behaviors known.
 Shelled protozoa have the simplest
exoskeletons
 Basic enzymes systems support all types of
nutrition: autotrophic, saprozoic and holozoic.
 Many have developed means of locomotion
31

32. 32
Classification (Levine et al., 1980)
Subkingdom Protozoa
1. Phylum Ciliophora (Ciliates)
2. Phylum Sarcomastigophora
3. Phylum Apicomplexa
4. Phylum Microspora
5. Phylum Labyrinthomorpha
6. Phylum Asecterospora
7. Phylum Myxozoa

33. 33
Phylum Ciliophora
 Defining characteristics
– Body externally ciliated in at
least some lifecycle stages
 Have the highest degree of
subcellular specialization
and are considered
advanced protozoans
Paramecium feces

34. Phylum Ciliophora
 Most of the species are free living; quite a number are
commensal, some shortly parasitic and a large number
symphorionts on variety of hosts
 Simple cilia or compound ciliary organelles are present
at least one stage in life cycle
34

35. Phylum Ciliophora
35
Paramoecium

36. Phylum Ciliophora
 Nuclei are of two types
 Presence of contrctile vacuole(s)
Kingdom Protozoa
36

37. Phylum Ciliophora
 Asexual reproduction by binary transverse fission, basically
homothetogenic (Miotic fission across the rows of cilia of a
protozoan) and generally parakinetal, but budding & multiple
fission also occur
37

38. Phylum Ciliophora
38

39. 39
Cilia
 Cilia
– Hair-like structures by
which the organism
moves, collects food
and senses their
surroundings
 Fastest of all the
protozoans
Cilia structure

40. Ciliate Biology
 Oral groove
 Cytostome
 Cytoproct
 Contractile vacuole
 Parakinetal: anlage for the
opisthe oral apparatus is
derived directly from the
first ordinary somatic ciliary
row right of the glabrous
stripe and has no
connection with parental
mouth structures.
Paramecium

41. 41
Ciliate Lifestyles
 65% of all ciliate
species are free-living
and mobile
 Some ciliates form
colonial aggregations
and have sessile
habits
 Other ciliates have
symbiotic relationships
in invertebrates and
vertebrates
Vorticella

42. Some more ciliates
42
Vorticella
Nassula

43. Some more ciliates
43
Podophrya Prorodon

44. Phylum Sarcomastigophora/
Zoomastigophora
 Nucleus is one type, except hereokaryotic
Foraminiferans
 Locomotion by either pseudopodia or flagella
or both
 Asexual reproduction, essentially syngamy
when sexual
 Three Sub-phyla: Mastigophora, Opalinata &
Sarcodina
Kingdom Protozoa
44

45. Mastigophora (examples)
 Trypanosoma
 Euglena
 Noctiluca
 Giardia
 Leishmania
45

46. Opalinata (examples)
 Opalina
 Protoopalina
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47. Sarcodina (examples)
 Amoeba
 Entamoeba
 Elphidium
47

48. 48
Phagocytosis

49. 49
Amoebas and Humans

50. 50
Foraminiferans (Amoeboid Protists)
Individuals secrete multi-
chambered tests, generally
made of calcium carbonate
(CaCo3)or agglutinated sediment
particles.
Over 50,000 species are
recognized, both living
(10,000) and fossil (40,000).
They are usually less than 1 mm
in size, but some are much
larger, the largest species
reaching up to 20 cm
Foram. tests

51. 51

52. 52
They are
of many
varieties…
indeed

53. 53
Foraminiferans
 Feed on diatoms
and algae, very slow
movers
 Organisms are
extremely common
and form ooze
– White cliffs of
Dover are
foraminiferan
tests

54. 54
Phylum Radiozoa/Radiolaria
 Defining characteristics
– Body is divided into distinct
zones separated by a
perforated membrane or
capsule
 Have pseudopodia
supported with thin
microtubules that give a
spiny rayed appearance

55. 55
Fascinating
Radiolarians
Anthocyrtium hispidum

56. 56
Radiolarians
 Have shells made of silicon dioxide that
can be very intricate
 Feed on diatoms and other phytoplankton
 Benthic individuals move by use of
pseudopodia
– Can occur in large concentrations that form
ooze as well

57. 57
The Flagellated Protozoans
 Characterized by the
possession of a
definite body shape
and the possession of
one or more flagella
 Most species are
free-living and mobile
Noctiluca

58. 58
Phytoflagellated Protozoans
 Have chlorophyll and obtain energy directly
from the sunlight
 Some are strictly autotrophic or heterotrophic
– Some are a combination of both
 Both the Euglena and the dinoflagellates are
examples of phytoflagellated protozoans

59. 59
Phytoflagellated Protozoans
Noctiluca
Euglena
Ceratium
Chlamydomonas

60. 60
Dinoflagellates
 Know for bioluminescence and highly toxic red
tides
– Dense aggregations produce saxitoxin killing fish and
crustaceans
 Also contaminates shellfish causing diarrheic
shellfish poisoning
 Some benthic dinoflagellates produce a
neurotoxin that accumulates in tropical fish called
Ciguatera

61. 61

62. 62

63. 63

64. 64
Morphology

65. 65

66. 66

67. 67
Zooflagellated Protozoans
 Free-living forms
– Most individuals are sessile and have a single
flagellum that beats to obtain food and nutrients
 Parasitic forms
– 25% of zooflagellate spp. are parasitic in humans,
invertebrates, and other vertebrates
– Usually have complex lifecycles with intermediate
hosts
– Malaria is caused by the genus Plasmodium
technically a member of the phylum Sporozoa

68. Phylum Apicomplexa/ Sporozoa
 All species are parasitic in nature
 Anterior part of the body forms an apical
complex
 This apical complex is made up of polar rings,
rhoptries, micronemes, conoid and sub
pellicular microtubules
 Microspore present in some stages
 Sexual reproduction by syngamy
68

69. Phylum Apicomplexa/ Sporozoa
69

70. 70

71. 71
Gregarina
Monocystis
Plasmodium

72. Phylum Microspora
 Obligatory intracellular parasites found nearly
all animal groups
 Spores unicellular, each with imperforate wall,
containing uninucleate or dinucleate
sporoplasm
72

73. Phylum Microspora
 Spore with simple or complex extrusion
apparatus associated with polar tube & polar
cap
73

74. Phylum Microspora
 Mitochondria absent in
spores
74
• Usually
dimorphic in
sporulation
sequence

75. 75
Phylum Microspora example
Nosema

76. Phylum Labyrinthomorpha
 Mostly marine or estuarine
 Trophic stage having ectoplasmic network, with
spindle shaped or spherical non amoeboid
cells
76
Labyrinthula

77. Phylum Labyrinthomorpha
 In some genera, amoeboid cells are move
within the cytoplasmic network by gliding
77

78. Phylum Labyrinthomorpha
 Unique cell-surface organelle, associated to
ectoplasmic network
 Saprophytic or
parasitic on algae;
Zoospores are
produced by most
species
78

79. Labyrinthomorpha examples
79
Labyrinthula

80. Phylum Ascetospora
 All are parasitic.
 In most of the cases spores are multicellular.
 Spores with one or more sporoplasm.
 Spores without polar capsules or polar
filaments.
 Haplosporidium, Coelosporidium, Paramyxa,
Marteilia.
80

81. 81
Spore orientation
of
Haplosporidium

82. Haplosporidium
Kingdom Protozoa
82

83. Phylum Myxozoa
 All species are parasitic.
 Spores are of multicellular origin, with one or
more polar capsules and sporoplasms.
 Each spore with 1, 2 or 3 (rarely more) valves.
 Myxidium, Myxobolus, Trilospora,
Triactinomyxon.
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84. Kingdom Protozoa
84

85. Phylum Myxozoa example
Kingdom Protozoa
85
Myxidium