PROTOZOANS
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“First animals”
constitute of diverse group of eukaryotic
unicellular organisms
all life function of protozoans is carried
out within the confines of a single cell
Although protozoans have no organ and
tissues, they are far from a “simple”
organism, for the cells of some species
show the greatest complexity and
internal organization of any organisms
on Earth
Characteristics:
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small size
unicellular (but some species are colonial
or have multicellular stages)
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body naked or covered by an
exoskeleton (test) formed of silica or
calcium carbonate. Protozoans always
require moisture, which restricts them
to a narrow range of environmental
conditions in fresh water or marine
habitats, the soil, decaying organic
matter or inside the bodies of plants and
animals.
About 10,000 species have close (symbiotic)
relationships with animals or plants.
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Mutualistic - both partners benefit
Commensalistic - one benefits, while
the other is neither helped nor harmed
Parasitic - the parasite benefits; the host
is harmed.
Four TYPES (Phyla) based on their locomotion
1. Sarcodina
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Locomotion uses Pseudopods (pseudopodia)
are the amoeboid protozoa which trap
food by some form of pseudopodial
action, pseudopodia which range from
the single blunt lobopodium to the
delicate tracery of reticulopodia which
project from a foraminiferan shell. Both
are designed to perform the same
function, to trap food.
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have no cytostomes and have bodies of
a less organized shape than most
protozoa.
Mastigophora
• the flagellates make up a large and
heterogeneous group of Protozoa,
varying in size from 1500 micrometers
in diameter to around 3 micrometers
long.
• The common morphological flagellate
type is spherical to cylindrical on an
anteroposterior axis.
• Based on the flagellum as a means of
locomotion, Flagellata are very diverse
in:
o Shape
o colony formation
o internal structure
o external shell or test
o color
o physiology
o reproduction
o choice of environment.
3. Ciliophora
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The ciliated protists are typically longer
than 50 μm in body length and so are
conspicuous microbial eukaryotes.
quickly moving protists locomote using
files of cilia (kineties) organized on the
cell surface.
NUCLEAR DIMORPHISM (possession of 2 Kinds
of Nuclei)
1. Micronucleus
• NOT transcriptionally active and
which
is
considered
the
equivalent of the germ line in
multicellular organisms.
• participates in Conjugation
o sexual process of ciliates
o
2.
3rd Major feature to
characterize this group
They cause disease in a wide variety of
animals from earthworms and rats to
silkworms (the disease called pebrine)
and fish.
Macronucleus
• Transcriptionally
active
and
which
is
typically
a
developmental product of the
amplification of the micronuclear
or germ-line DNA.
Malaria is easily the most important
sporozoan disease, especially for
humans.
Malarian organism live primarily
in the Blood cell
CILIATES as large cells are the top predators or
heterotrophs in microbial food webs when
metazoans are absent.
As heterotrophs, they feed upon bacteria,
smaller protists, and even other ciliates in
ecosystems from the poles to the tropics and
from terrestrial soils to the sediments around
deep-sea hydrothermal vents.
Ciliates can also be symbionts of other
organisms, ranging from commensals found in
the stomachs of ruminants to parasites of fish.
Ciliates,
such
as
TETRAHYMENA
AND
PARAMECIUM, whose genomes have been
sequenced, serve as model organisms for cell
and molecular biology.
4. Sporozoa
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parasitic protozoans that lack
locomotor organs:
o no cilia
o no flagella
o no pseudopods.
Intracellular parasites
They usually pass from host to
host in protective capsules called
spores which enclose zygotes or
juvenile states; however, those
species that are transmitted by
blood-sucking
vectors,
like
mosquitoes, lack true spores.
Very large and diverse class with
at least four subclasses and
many thousands of species.
Coccidiosis, which afflicts poultry and
cattle is second. Some sporozoans, like
the malarial organism, live
Coccidia, live in the Epithelial
cells lining the intestine.
Other pathogenic species:
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Trypanosoma Protozoa
Giardia Protozoa
Plasmodium Protozoa