CLASSIFICATION OF PROTOZOA

Phylum Protozoa is classified into 4 distinct sub-phyla on the basis of type of locomotory organelles found in them. The 4 sub-phyla of phylum Protozoa are as follows:

Sarcomastigophora
Sporozoa
Cnidospora
Ciliophora

1. SARCOMASTIGOPHORA

Locomotory organelles may be Pseudopodia or Flagella.
Nucleus is monomorphic.
Asexual reproduction is by binary or multiple fission.
Sexual reproduction occurs by fusion of gametes.

Sub-phylum Sarcomastigophora is further divided into 3 Super classes i.e.,

-Mastigophora

-Opalinata

-Sarcodina

(a) MASTIGOPHORA (SUPER CLASS)

Flagella are present as locomotory organelles, so they are also called Flagellata. Flagella also acts as food capturing organ.
Body is covered by a layer of very thin cuticle or pellicle.
Nutrition is holozoic, holophytic or saprozoic.
Asexual reproduction by longitudinal fission.

Super class Mastigophora has further 2 classes i.e., Phytomastigophora and Zoomastigophora.

(i) PHYTOMASTIGOPHORA (CLASS)

They possesses chromatophores.
Only 1 or 2 flagella are found.
Nutrition is holophytic.
Ex- Euglena

(ii) ZOOMASTIGOPHORA (CLASS)

Chlorophyll bearing chromatophores are absent.
In addition to pseudopodia, more than 2 flagella are present as locomotory organelles.
Undulating membrane may be present.
Nutrition is holozoic.
Ex- Trypanosoma

(b) OPALINATA (SUPER CLASS)

All are parasites of frogs and toads.
Body is covered by flagella and arranged in oblique rows over the entire body surface.
Nuclei are monomorphic.
Reproduction by simple binary fission or by gamete formation.
Ex- Opalina

(c) SARCODINA (SUPER CLASS)

Locomotory organelle is Pseudopodia.
Body is not usually covered by pellicle.
Gamete formation is more common.

Super class Sarcodina is further divided into 3 classes i.e., Rhizopoda, Actinopoda, and Piroplasmea.

(i) RHIZOPODA (CLASS)

Locomotory organelles are lobopodia or filopodia. Axopodia are absent.
All are creeping forms.
Ex- Amoeba, Entamoeba

(ii) ACTINOPODA (CLASS)

Axopodia is found as locomotory organelle.
Test may or may not be present.
Reproduction is by both sexual and asexual method.
Gametes are usually flagellated.
Ex- Actinophrys

(iii) PIROPLASMEA (CLASS)

They are small, round, rod shaped or amoeboid forms.
Parasites of R.B.Cs of vertebrates.
Ex- Babesa

2. SPOROZOA

All of them are parasites.
Locomotory organelles are absent. But gametes may have cilia or flagella.
Body is covered by thick cuticle or pellicle.
Asexual reproduction by multiple fission.

Sub-phylum Sporozoa is further classified into 3 classes, such as: Telosporea, Haplosporea, Toxoplasmea.

(a) TELOSPOREA (CLASS)

Pseudopodia are generally absent. Locomotion is by gliding body movement.
Reproduction is both sexual and asexual.
Ex- Plasmodium

(b) TOXOPLASMEA (CLASS)

Locomotory organelles are absent in all the stages.
Reproduction is by binary fission.
Ex- Toxoplasma

(c) HAPLOSPOREA (CLASS)

Pseudopodia may be present, but flagella is absent.
Spore cases are present.
Reproduction is only asexual.
Ex- Icthyosporidium

3. CNIDOSPORA

All are parasites.
Zygotes gives to one or more trophozoites.
Trophozoites are multinucleated.

Cnidospora has 2 distinct classes, such as:

Myxosporidea and Microsporidea.

(a) MYXOSPORIDEA (CLASS)

Parasites of fishes.
Spores are of multicellular origin.
Spores possesses a bivalved membrane.
Ex- Myxobolus.

(b) MICROSPORIDEA (CLASS)

Endoparasites of Arthropods and Vertebrates.
Spores are of unicellular origin.
Small spores with univalved membrane.
Ex- Nosema

4. CILIOPHORA

Cilia are the locomotory organelles.
Posses 2 nuclei i.e., one meganucleus (vegetative nucleus) and another micronucleus (reproductive nucleus).
Nutrition is heterotrophic.
Asexual reproduction is by binary fission or budding.
Sexual reproduction is by conjugation, autogamy or by cytogamy.

Sub-phylum Ciliophora has only one class i.e., Ciliata.

(a) CILIATA (CLASS)

Cilia are present throughout the life.
Nuclear dimorphism is marked.
Anal aperature (cytopyge) is permanent.
Ex- Paramecium