CLASSIFICATION OF PROTOZOA
· Most accepted
classification of Protozoa is given by B. M. Honigberg and others based on the
scheme given by the committee on Taxonomy and Taxonomic problems of the society
of Protozoologists. They classified the Phylum Protozoa into four major groups
based on the Structure and the part involved in the Locomotion.
a) Sub-phylum I: Sarchmastigophora
b) Sub-phylum II: Sporozoa
c) Sub-phylum III: Cnidospora
d) Sub-phylum IV: Ciliophora
A) SUB-PHYLUM I: SARCOMASTIGOPHORA
·
Sarcodes - fleshy; mastix - whip; phoros - bearing
·
Locomotion in
Sub-phylum Sarchmastigophora is brought about by Flagella or Pseudopodia or
both.
·
Other important
feature of this Sub-phylum Sarchmastigophora is the presence of Monomorphic
nuclei.
·
The Sub-phylum
Sarchmastigophora is further divided in to 3 Super classes:
a)
Super class 1:
Mastigophora
i)
Class 1:
Phytomastigophora
ii)
Class 2:
Zoomastigophora
b)
Super class 2:
Opalinata
c)
Super class 3:
Sarcodina
i)
Class 1:
Rhizopodea
ii)
Class 2: Piroplasmea
iii) Class 3: Actinopodea
a) SUPER CLASS 1: MASTIGOPHORA
·
Mastix - whip; phoros - bearing.
·
The body of the
animals belonging to this Super class Mastigophora is covered by Pellicle.
·
The locomotory
organelles are Flagella.
· In this Super
class Mastigophora, the Asexual reproduction occurs by Longitudinal Binary
Fission.
·
The Super class
Mastigophora includes 2 Classes:
i)
Class 1: Phytomastigophora
ii)
Class 2: Zoomastigophora
i) Class 1: Phytomastigophora
·
Phyton - plant; Mastix - whip; phoros – bearing.
·
Class 1:
Phytomastigophora have Chromatophores with Chlorophyll.
·
The nutrition
in these organisms is mainly Holophytic which takes place by Phototrophy.
·
Phytomastigophora
are free living organisms.
·
The reserve
food in these organisms is Starch or Paramylon.
·
Organisms
belong to Phytomastigophora may have 1 or 2 flagella.
·
Example – Euglena
sp., Ceratium sp. and Noctiluca sp.
ii) Class 2: Zoomastigophora
·
Zoon - animal; Mastix - whip; phoros – bearing.
·
Organisms
belong to Class 2: Zoomastigophora do not have Chlorophyll bearing Chromatophores.
·
Zoomastigophora
are mostly Parasitic.
·
The mode of nutrition
in Zoomastigophora is Holozoic or Saprozoic.
·
The reserved
food in Zoomastigophora is Glycogen.
·
Zoomastigophora
may have one to many Flagella.
·
Example – Leishmania
sp., Trypanosoma sp. and Trichomonas sp.
b) SUPER CLASS 2: OPALINATA
· The organisms
belonging to the Super class Opalinata live as Commensals or Parasites in the
gut of anurans.
·
The body of
Opalinata is covered by oblique rows of Cilia-like Flagella.
·
Opalinata
organisms may have 2 or many Nuclei also the Nuclei are Monomorphic.
·
Opalinata
undergo Asexual reproduction by Binary fission or Syngamy. Sexual reproduction
takes place by Anisogamy.
·
Example – Opalina
and Zelleriella.
c) SUPER CLASS 3: SARCODINA
·
Sarcode – fleshy.
· The locomotion
in the organism belonging to the Super class Sarcodina is brought about by
Pseudopodia.
·
The body of
Sarcodina is Amoeboid without definite Pellicle.
·
The nutrition
is Holozoic or Saprozoic.
·
The Super class
Sarcodina is further divided into 3 classes:
i)
Class 1:
Rhizopodea
ii)
Class 2:
Piroplasmea
iii)
Class 3:
Actinopodea
i) Class 1: Rhizopodea
· The Pseudopodia
of the animals in this Class Rhizopodea are in the form of Lobopodia, Filopodia
or Reticulopodia without Axial filaments.
·
The Rhizopodea
includes Amoebas, Foraminiferans and Mycetozoans.
·
Rhizopodea are
mostly free living and a few are also Parasitic.
·
In Amoebas, the
body is naked. In Foraminiferans the body is covered by porous calcareous
shell.
·
Example – Amoeba
sp., Entamoeba sp. and Elphidium sp.
ii) Class 2: Piroplasmea
·
The animals
belonging to the Class Piroplasmea are Parasitic.
·
Locomotory
structures are absent in Piroplasmea.
·
Spores are also
absent.
·
Piroplasmea are
the small parasites in the Red blood cells (RBC) of Vertebrates.
·
Example – Babesia
sp.
iii) Class 3: Actinopodea
·
Actis - ray; podos - foot.
· The Pseudopodia
of the animals belonging to the Class Actinopodea are in the form of Axopodia
with Axial filaments, Radiating from the spherical body.
·
Actinopodea are
Planktonic.
·
Actinopodea
class includes Heliozoans, Radiolarians and Acanthareans.
· Radiolarians
and Acanthareans are marine forms whereas Heliozoans are both marine and fresh
water forms. Skeletons of Radiolarians have siliceous shells. The shells of
dead Radiolarians accumulate on the ocean floor to form Radiolarian ooze.
·
Examples – Collozoum
sp., Actinophrys sp. and Acanthometra sp.
·
The animals
belonging to this Sub-phylum Sporozoa are exclusively Endoparasites.
·
Special
locomotory organelles are absent in these animals.
·
Sometimes
Pseudopodia are present which are useful only for ingestion of food.
·
Sporozoites are
Merozoites bear anterior apical complex that helps penetrate host cells.
·
This Sub-phylum
Sporozoa includes 3 Classes:
i) Class 1: Telosporea
ii) Class 2: Toxoplasmea
iii) Class 3: Haplosporea
i) Class 1: Telosporea
·
The Sporozoites
are long in these animals.
·
Reproduction is
both asexual and sexual.
·
Telosporea are
blood and gut parasites of vertebrates.
·
Sexual
reproduction is by Isogamy or Anisogamy.
·
Example – Monocyctis
sp., Eimera sp. and Plasmodium sp.
ii) Class 2: Toxoplasmea
·
In this Class Toxoplasmea,
reproduction is only Asexual type which takes place by internal Budding where
two daughter cells are produced within the mother cell and the mother cell is
finally destroyed in the process of reproduction.
·
Spores are
absent.
·
Example – Toxoplasma
sp.
iii) Class 3: Haplosporea
·
The spores in
this Class Haplosporea are Amoeboid.
·
Reproduction is
only Asexual type taking place through Multiple fissions.
·
Example – Haplosporidium
sp. and Ichthyosporidium sp.
·
Knide - nettle; spora
- seed.
·
The animals
belonging to the Sub-phylum Cnidospora are parasitic.
·
Locomotory
organelles are absent.
·
Spores are
present with one or more Polar filaments. Polar filaments are special and
unique features of these Cnidospora. When these spores infect a host, the polar
filament is discharged and it gets attached to the host tissue.
·
This Sub-phylum
Cnidospora includes 2 Classes:
i) Class 1: Myxosporidea
ii) Class 2: Microsporidea
i) Class 1: Myxosporidea
·
The spores of
the animals of this Class Myxosporidea are large and develop from several
Nuclei.
·
Myxosporidea
are generally Extracellular parasites.
·
The Spores of
this Class Myxosporidea have two polar filaments and have two to three valves.
·
Example – Myxobolus
sp.
ii) Class 2: Microsporidea
·
The Spores of
the animals of this Class Microsporidea are small and are developed from only
one nucleus. These spores have single valve.
·
Microsporidea
are generally Intracellular parasites.
·
Microsporidea
have a single polar filament.
·
Example – Nosema
bombycis.
D) SUB-PHYLUM IV: CILIOPHORA
·
Cilium - eye lid with lashes; phoros - bearing.
·
Ciliophorans
are complex of all the Protozoans.
·
Locomotory
organelle of all the animals of this Sub-phylum Ciliophorans is Cilia.
·
Cilia also help
in feeding at some stage of the life cycle of the animals.
·
The Nuclei of
these organisms are Dimorphic.
ü Macronucleus is vegetative and Polyploid.
ü Micronucleus is reproductive and Diploid.
·
Asexual
reproduction takes place by Binary fission. Sexual reproduction takes place by
Conjugation.
·
Only one class
is included in this Sub-phylum Ciliophorans:
i)
Class 1: Ciliatea
i) Class 1: Ciliatea
·
Locomotory
organelles of Ciliatea are numerous hair-like Cilia.
·
One or more
Contractile vacuoles are present in these forms.
·
The nucleus is
dimorphic including both macro nucleus and micronucleus.
·
Example – Paramoecium
sp.,
Vorticella sp. and Balatidium sp.
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