Introduction Animal-like protists Classification of Phylum Protozoa Subphylum  Super classes  Classes  References Presentation Best of Luck

1. Protozoan Taxonomy
presentation

2. Outlines:
 Introduction
 Animal-like protists
 Classification of Phylum Protozoa
 Subphylum
 Super classes
 Classes
 References

3. Introduction:
• In 1674, Antony van Leewenhoek described the first
protozoan “animalcule”.
• The protozoa were classified into four major groups
based on their means of locomotion.
 Flagellates (Mastigophora)
 Cilia (Ciliophora or Infusoria)
 Amoeba (Sarcodina)
 Sporozoa

4. Cont...
• Recent morphological, biochemical, and
phylogenetic analysis have resulted in the
development of a higher-level classification for the
protists, including the protozoa.
• In 2005, this scheme as a proposed by the
International Society of Protistologists.

5. Animal-like Protists:
• Animal-like protists are called protozoa.
• Protozoa are single-celled eukaryotes that share
some traits with animals.
• Protozoa defined as “microscopic acellular
animals existing singly or in colonies, without
tissue and organs, having one or more nuclei”.
• They are heterotrophs.
• Animal- like protists include the flagellates,
ciliates, and the sporozoans.

6. Classification of Phylum Protozoa

7. Phylum Sacromastigophora:
• With over 18,000 described species,
Sarcomastigophora is the largest protozoan phylum
and has the following characteristics:
• Unicellular or colonial
• Locomotion by flagella, pseudopodia, or both
• Autotrophic , saprozoic (living in decaying
organic matter), or heterotrophic.
• Single type of nucleus
• Sexual reproduction (usually)

8. Subphylum Mastigophora:
(Flagellum Locomotion)
• Members of the subphylum Mastigophora (masti-
gofo-rah) use flagella in locomotion.
• Flagella may produce two-dimensional
i. whiplike movements or
ii. helical movements.
• These movements that push or pull the protozoan
through its aquatic medium.

9. Class Phytomastigophorea:
(Phytoflagellated protozoa)
• The subphylum Mastigophora has two classes.
• It possess chlorophyll and one or two flagella.
• Phytomastigophoreans produce a large portion of the
food in marine food webs.
• Much of the oxygen used in aquatic habitats comes
from photosynthesis by these marine organisms.

10. Cont…
• Marine phytomastigophorean include the
dinoflagellates , have one flagellum that wraps
around the organism in a transverse groove.
• The primary action of this flagellum causes the
organism to spin on its axis.
• A second flagellum is a trailing flagellum that pushes
the organism forward.
• In addition to chlorophyll, many dinoflagellates
contain xanthophyll pigments, which give them a
golden brown color.

11. Cont…
• At times, dinoflagellates become so numerous that
they color the water.
• Several genera, such as Gymnodinium, have
representatives that produce toxins.
• Periodic “blooms” of these organisms are called “red
tides” and result in fish kills along the continental
shelves.

12. Cont…
• Humans who consume tainted molluscs or fish
may die.
• The Bible reports that the first plague Moses
visited upon the Egyptians was a blood-red tide that
killed fish and fouled water.
• Indeed, the Red Sea is probably named after
these toxic dinoflagellate blooms.
• Phyloflagellated protozoa possess one or two flagella
and produce a large portion of the food in marine
food webs.

13. Cont...
Oxygen used in aquatic habitats comes
from photosynthesis by these marine
protozoa.
Euglena is a fresh water .
Each chloroplast has a pyrenoid, which
synthesis and stores polysaccharides.
In the dark, euglenoids lack chloroplasts
and are always heterotrophic

14. Euglenozoa:
• Members of the Euglenozoa are either;
• Phytoflagellated (photosynthesizing) protozoa that
possess chlorophyll and acquired their chloroplasts
through endosymbiosis
• Zooflagellated (particle-feeding and parasitic)
protozoa.
• They have one or two flagella inserted into an apical
pocket, possess two kinetosomes and the
mitochondria have discoid cristae.

15. Cont..
• Euglena orients toward light of certain intestities.
• Pigment shield (stigma) covers a photoreceptor at
the base of the flagellum.
• The stigma permits light to strike the photoreceptor
from only one direction and move in relation to a
light source.
• Euglenoid flagellates are haploid and reproduce by
longitudinal binary fission.
• Sexual reproduction in these species is unknown.

16. Structure of Euglena

17. Class Zoomastigophorea
(Zooflagellated protozoa)
• Members of the class Zoomastigophorea lack
chloroplasts and are heterotrophic.
• Protists also have a single, large mitochondrion that
that contains an organized mass of DNA called a
kinetoplast.
• Most important species is Trypanosoma brucei.
• Species are divided into three subspecies T. b. brucei,
T. b. gambiense often reffered as the Trypanosoma
brucei complex.

18. Cont…
• Three subspecies is a parasite of non-human
mammals:
• Two cause Africa sleeping sickness in humans and
Tsetse flies are intermediate hosts and vectors of all
three subspecies.
• When a testse fly bites an infected human or
mammal, it picks up parasites in addition to its meal
of blood.
• Trypanosomes asexually in the gut of the fly for
about 10 days, then migrate to the salivary glands.

19. Trypanosoma brucei

20. Cont...
• When the infected testse fly bites another vertebrate
host, the parasites travel with salivary secretions into
the blood of a new definitive host.
• Parasites multiply asexually in the new host and
again transform through a number of body forms.
• Parasites may live in the blood, lymph spleen, central
nervous system and cerebrospinal fluid.
• When trypanosomes enter the central nervous
system, they cause general apathy, mental dullness
and lack of coordination.

21. Cont…
• “Sleepness” develops and the infected individual
may fall asleep during normal daytime activities.
• Death results from the pathology occuring in the
nervous system, as well as from heart failure,
• malnutrition, and
• other weakened conditions.
• If detected early, sleeping sickness is ciurable.
• Infection has advanced to the central nervous system.

22. Subphylum Sarcodina:
Pseudopodia and Amoeboid locomotion:
• Members of the subphylum Sarcodina are the amoebae.
• When feeding and moving, they form temporary cell
extensions called pseudopodia.
• Lobopodia are broad cell processes containing ectoplasm
and endoplasm and are used for locomotion and engulfing
food.
• Filopodia contain ectoplasm only and provide a constant
two-way streaming that delivers food in a conveyor-belt
fashion.

23. Cont…
• Reticulopodia are similar to filopodia, they branch
and rejoin to form a netlike series of cell extensions.
• Axpodia are thin, filamentous, and supported by a
central axis of microtubules.
• Food caught on axopodia can be delivered to the central
cytoplasm of the amoeba.
• This group lack a test, cell wall, or other supporting
structures.
• These amoebae are naked and normally found on
shallow-water substrates of freshwater ponds, lakes, and
slow-moving streams.

24. Variations in Pseudopodia

25. Superclass Rhizopoda:
Class Lobosea:
• The most familiar amoebae belong to the superclass
Rhizopoda, Class Lobosea and the genus Amoeba.
• These amoebae are naked (they have no test or shell)
and are normally found on shallow-water substrates
of freshwater ponds, lakes, and slow-moving
streams.
• Where they feed on other protists and bacteria.

26. Cont…
• They engulf food by phagocytosis.
• In the process, food is incorporate into food
vacoules.
• Binary fission occurs when an amoeba reaches a
certain size limit.
• Tests are protective structures that the cytoplasm
secrets.
• They may be calcareous, siliceous, and
proteinaceous.
• Tests may be composed of sand or other debris
cemented into a secreted matrix.

27. Cont…
• Arcella is a common freshwater, shelled amoeba.
• It has a brown, proteinaceous test that is flattened on
one side and domed on the other.
• Pseudopodia project from an opening on the
flattened side.
• Difflugia is another common freshwater, shelled
amoeba.
• Its test is vase shaped and is composed of mineral
particles embedded in a secreted matrix.

28. Difflugia Oblangata

29. Entamoebida:
• First rank have no flagella or centrioles.
• Lack mitochondria.
• All free-living amoebae are particle feeders,
using their pseudopodia to capture food; few are
pathogenetic.
• Example: Entamoeba histolytica causes one form
• of dysentery in humans.
• Amoebic dysentry is a worldwide problem that
plagues humans in crowded, unsanitary conditions.

30. Cont…
• Amoeba live in the folds of the intestinal wall,
feeding on starch and mucoid secretions.
• They pass from one host to another in the form of
cysts transmitted by fecal contamination of food or
water.
• After ingestion by a new host, amoeba leave their
cysts and take up residence in the hosts intestinal
wall.
• It causing multiple of problems.

31. Subphylum Actinopoda:
(Foraminifera, Heliozoans, Radialoria):
• Foraminiferans are primarily a marine group of
amoebae.
• Foraminiferans possess reticulopodia and secrete a
test that is primarily calcium carbonate.
• As foraminiferans grow, they secrete new, larger
chambers that remain attached to the older
chambers.
• Test enlargement follows a symmetrical pattern that
may result in a straight chain of chambers or a spiral
arrangement that resembles a snail shell.

32. Foraminifera:
• Many of these tests become relatively large; For
example: “Mermaid’s pennies,” found in Australia,
may be several centimeters in diameter.
• Foram tests are abundant in the fossil record since
the Cambrian period.
• They make up a large component of marine
sediments, and their accumulation on the floor of
primeval oceans resulted in limestone and chalk
deposits.
• The white cliffs of Dover in England are one
example of a foraminiferan-chalk deposit.

33. Heliozoans:
• Heliozoans are aquatic amoebae that are either
planktonic or live attached by a stalk to some
substrate.
• (The plankton of a body of water consists of those
organisms that float freely in the water.)
• Heliozoans are either naked or enclosed within a test
that contains openings for axopodia.

34. Radiolarians:
• Radiolarians are planktonic marine and freshwater
amoebae.
• They are relatively large; some colonial forms may
reach several centimeters in diameter.
• They possess a test (usually siliceous)of long,
movable spines and needles or of a highly sculptured
and ornamented lattice.
• When radiolarians die, their tests drift to the ocean
floor.

35. Cont…
Foraminifera Radiolarians
Heliozoans

36. Phylum Labyrinthomorpha:
• The very small phylum Labyrinthomorpha consists
of protozoa with spindle-shaped, nonamoeboid,
vegetative cells.
• In some genera, amoeboid cells use a typical gliding
motion to move within a network of mucous tracks.
• Most members are marine, and either saprozoic or
parasitic on algae or seagrass.
• Several years ago, Labyrinthula killed most of the
“eel grass” (a grasslike marine flowering plant).

37. Phylum Apicomplexa:
• Members of the phylum Apicomplexa are all
parasites. Characteristics of the phylum include:
• Apical complex for penetrating host cells
• Single type of nucleus
• No cilia and flagella, except in certain reproductive
stages
• Life cycles that typically include asexual
(schizogony, sporogony) and sexual (gametogony)
phases.

38. Class Sporozoea:
• The most important species in the phylum
Apicomplexa are members of the class Sporozoea.
• The class name derives from most sporozoeans
producing a resistant spore or oocyst following sexual
reproduction. Some members of this class, including;
• Plasmodium and coccidians, cause a variety of
diseases in domestic animals and humans.
• Many are intracellular parasites, and their life cycles
have three phases.

39. Cont…
• Schizogony is multiple fission of an asexual stage in
host cells to form many more (usually asexual)
individuals, called merozoites.
• Some of the merozoites undergo gametogony, which
begins the sexual phase of the life cycle.
• The parasite forms either microgametocytes or
macrogametocytes.
• Microgametocytes undergo multiple fission to
produce biflagellate microgametes that emerge from
the infected host cell.

40. Cont…
• The macrogametocyte develops directly into a single
macrogamete.
• A microgamete fertilizes a macrogamete to produce a
zygote that becomes enclosed and is called an oocyst.
• The zygote undergoes meiosis, and the resulting cells
divide repeatedly by mitosis.
• This process, called sporogony, produces many
rodlike sporozoites in the oocyst.

41. Plasmodium Life Cycle:
• One sporozoean genus, Plasmodium, causes malaria
and has a long history.
• Malaria contributed significantly to the failure of the
Crusades during the medieval era, and along with
typhus, has devastated more armies than has actual
combat.
• Recently (since the early1970s), malaria has
resurged throughout the world.
• Over 100 million humans are estimated to annually
contract the disease.

42. l
Life cycle of Plasmodium

43. Cont..
• The Plasmodium life cycle involves vertebrate and
mosquito hosts.
• A mosquito takes in gametocytes during a meal of
blood, and the gametocytes subsequently fuse.
• The zygote penetrates the gut of the mosquito and
transforms into an oocyst.
• Sporogony forms haploid sporozoites that may enter a
new host when the mosquito bites the host.
• The symptoms of malaria recur periodically and are
called paroxysms.

44. Cont…
• Chills and fever correlate with the maturation of
parasites, the rupture of red blood cells, and the
release of toxic metabolites.
• Four species of Plasmodium are the most important
human malarial species.
• P. vivax causes malaria in which the paroxysms recur
every 48 hours.
• P. falciparum causes the most virulent form of
malaria in humans.

45. Cont…
• Other members of the class Sporozoea also cause
important diseases.
• Coccidiosis is primarily a disease of poultry, sheep,
cattle, and rabbits.
• Two genera, Isospora and Eimeria, are particularly
important parasites of poultry.
• Another coccidian, Cryptosporidium, has become
more well known with the advent of AIDS since it
causes chronic diarrhea in AIDS patients.

46. Cont…
• Toxoplasmosis is a disease of mammals, including
humans, and birds.
• Sexual reproduction of Toxoplasma occurs primarily
in cats. Infections occur when oocysts are ingested
with food contaminated by cat feces.
• Most infections in humans are asymptomatic, and
once infection occurs, an effective immunity develops.
• However, if a woman is infected near the time of
pregnancy, or during pregnancy, congenital
toxoplasmosis may develop in a fetus.

47. Cont…
• Congenital toxoplasmosis is a major cause of
stillbirths and spontaneous abortions.
• Feruses that survive frequently show signs of mental
retardation and epileptic seizures.
• Congenital toxoplasmosis has no cure.
• Toxoplasmosis also ranks high among the
opportunistic diseases afflicting AIDS
patients.

48. Steps to avoid infection:
Steps to avoid infections by;
• Toxoplasma include keeping stray and pet cats away
from children’s
• sandboxes; using sandbox covers; and awareness, on
the
• part of couples considering having children, of the
potential dangers
• of eating raw or very rare pork, lamb, and beef.

49. Phylum Microspora:
• Members of the phylum Microspora commonly
called microsporidia, are small, obligatory
intracellular parasites.
• Nosema bombicus parasitizes silkworms causing the
disease pebrine, and N. apis causes serious dysentery
(foul brood) in honeybees.
• These parasites have a possible role as biological
control agents for insect pests.

50. Cont…
• For example, the U.S. Environmental Protection
Agency.
• It has approved and registered N. locustae for use
in residual control of rangeland grasshoppers.
• Recently, four microsporidian genera have been
implicated in secondary infections of
immunosuppressed and AIDS patients.

51. Phylum Acetophora:
• Acetospora is a relatively small phylum that consists
exclusively of obligatory extracellular parasites
characterized by spores lacking polar caps or polar
filaments.
• The acetosporeans (e.g., Haplosporidium) primarily
are parasitic in the cells, tissues, and body cavities of
molluscs.

52. Phylum Ciliophora:
• The phylum Ciliophora includes some of the most
complex protozoa.
• Characteristics of the phylum Ciliophora include:
• Cilia for locomotion and for the generation of feeding
currents in water.
• Relatively rigid pellicle and more or less fixed shape.
• Distinct cytostome (mouth) structure.
• Dimorphic nuclei, typically a larger macronucleus
and one more smaller micronuclei.

53. Cilia and other Pellicular Structures:
• Cilia are generally similar to flagella, except that
they are much shorter.
• Many ciliates can reverse the direction of ciliary
beating and the direction of cell movement.
• Basal bodies (kinetosomes) of adjacent cilia are
interconnected with an elaborate network of fibers
that are believed to anchor the cilia and give shape to
the organism.

55. Cont…..
• Some ciliates have evolved specialized cilia.
• Cilia may cover the outer surface of the protozoan.
• Trichocysts:
are pellicular structures primarily used for
protection. They are rod like or oval organelles
oriented perpendicular to the plasma membrane.
• In Paramecium, they have a “golf tee” appearance.
The pellicle can discharge trichocysts, which then
remain connected to the body by a sticky thread.

56. Trichocysts :

57. Nutrition:
• Some ciliates, such as Paramecium, have a ciliated
oral groove along one side of the body.
• Cilia of the oral groove sweep small food particles
toward the cytopharynx, where a food vacuole
forms.
• When the food vacuole reaches an upper size limit,
it breaks free and circulates through the endoplasm.

58. Cont…
• Some free-living ciliates prey upon other protists or
small animals. Prey capture is usually a case of
fortuitous contact.
• The ciliate Didinium feeds principally on
Paramecium, a prey that
is bigger than itself.
• Didinium forms a temporary opening that can
greatly enlarge to consume its prey

59. References:
• Miller and Harley Book 5th and 10th Edition