What Is Phylum Protozoa? Classification, Characters, Example

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General characters of Phylum Protozoa –

1. Microorganisms are included in the phylum Protozoa and they are very simple organisms.
2. These are unicellular organisms and have one or more nuclei.
3. Their body may be naked or protected by a skeleton in the form of a pellicle, test, or cyst.
4. Their body comprises one cell that performs all the necessary functions. There is no physical division of labor in these.
5. These organisms are free-living, symbiotic or parasitic, free-living are aquatic and these organisms are found in clean water and salty or brackish water. These may be solitary or colonial. These parasites live outside or inside the bodies of plants and animals.
6. Their nutrition can be Holozoic (like animals), Holophytic (like plants), Saprozoic (Subsisting on dead organic matter), Saprophytic (feeding on liquid food), or parasitic.
7. Their digestion process is intracellular and the food vacuole is completed inside.
8. These may or may not have pseudopodia, flagella, cilia, or organs for locomotion.
9. Their respiration and excretion take place through their normal body surface.
10. In these, asexual reproduction occurs through binary fission, multiple fission, and budding.
11. In these, sexual reproduction occurs by the formation of gametes or by the fusion of adults.
12. In some microorganisms, the life cycle is complex and they exhibit reversion to their descendants.
13. These contain encystment to help deal with adverse conditions and spread the runes.
14. Information about more than 50 thousand species has been obtained.

Classification of phylum protozoa –

The phylum Protozoa is divided into four subphyla.

1. Subphylum – Sarcomastigophora
2. Subphylum – Sporozoa
3. Subphylum – Cnidospora
4. Subphylum – Ciliophora

First of all, we know about the suborder Sarcomastigophora

Subphylum I – SARCOMASTIGOPHORA

• In this subphylum of Phylum Protozoa, microscopic animals have Pseudopodia or flagella or both for walking or movement.
• In these, there are one or more nuclei of the same type.
• In these animals, asexual reproduction occurs through binary fission and multiple fission.

Superclass (A) Mastigophora (flagellata)

Which type of animals are kept in this super class of Phylum protozoa (Phylum protozoa in Hindi)? We will know about this.

• These animals are simple and ancient and have strong membranes.
• They have flagella as the organ for walking and this is how these animals move.
• In this, organisms provide autotrophic, heterotrophic, or both types of nutrition.

Class 1. Phytomastigophorea (Phytoflagellata)

• Chlorophyll-bearing chromatophores present.
• The nutrition of these organisms is holophytic or phototrophic.
• In these, food is in the form of starch or paramylon.
• These have one or two or more flagella.

ORDER 1 – Chrysomonadida

In this order or order of Phylum protozoa, we will study which type of organisms have been placed.

• Amoeba does not have an alimentary canal but has a stigma.
• Mainly there is one flagella but sometimes there are two or three.
• Chromatophores are one or two and are yellow, brown, or yellowish-green.
• They do not contain starch but leucosin and fat may be present.
• These contain siliceous cysts or fatty cysts.
• These animals are found in seawater or clean water.
• Examples – Chrysamoeba, Chromulina.

Order 2. Cryptomonadida

In this order of the phylum protozoa, we also know about what type of organisms have been placed.

• The anterior gullet reaches the middle part of the body.
• Flagella are two and unequal.
• These have two chromatophores and are yellow, brown, or colorless.
• Their reserve food is in the form of starch.
• Stigma is present in these.
• These organisms live in seawater or clean water.

Example – Chilomonas, Cryptomonas etc.

ORDER 3. Euglenoida

What types of animals have been placed in this order or group of Phylum protozoa, you will know about them.

• The posterior end leads into a main receptacle with an esophagus or cytopharynx.
• Flagella are 1 or 2, along with mastigonemes.
• These have many chromatophores and are green.
• These contain food items like paramylon or oil.
• Stigma is present in these.
• These creatures mostly live in clean water.

Example – Euglena, Peranema, Rhabdomanas.

ORDER 4. Volvocida (=Phytomonadida)

In this fourth order of the phylum protozoa, we also know about what types of animals have been placed.

• In this, the animals are small, covered with hard cellulose, and do not have an esophagus.
• There are mainly two flagella in these and sometimes more.
• The reserved foods in these are starch or oil.
• Stigma is present in these.
• They mostly live in clean water and some live in the form of colonies.

Examples – Chlamydomonas, Volvox.

ORDER 5. Chloromonadida

In this fifth order of the Phylum protozoa, which type of animals have been kept, you will know about them.

• Their body has a flat dorsal abdomen and along with it there is also a delicate thin membrane (Pellicle).
• The esophagus is present in these.
• These have two flagella, sometimes one or more.
• Chromatophores in these are green and many, some are also colorless.
• The reserved food item in these is oil.
• There is no stigma in these.
• They mostly live in clean water.

Example – Coelomonas

ORDER 6. Dinoflagellida

In this sixth order of the phylum protozoa, we also study what types of organisms have been placed.

• These are small and planktonic, naked and amoeboid, or with a thick pellicle or theca.
• 2 flagella are found in these.
• These organisms have many chromatophores and are yellow to brown.
• The reserved food in these is starch or oil or both.
• Stigma is present in these and there are also two contractile vacuoles.
• Most live in sea water and some are parasites.

Examples – Noctiluca, Ceratium, and Gymnodinium.

Class 2. Zoomastigophorea (=Zooflagellata)

We know about what types of animals have been kept in this class or the class of Phylum Protozoa.

• These animals are chlorophyll bearing but they do not have chromatophores.
• Their nutrition is holozoic and saprozoic.
• They are parasitic, symbiotic, or free-living.
• The reserved food in these is in the form of glycogen.
• These animals have more than one flagella.

ORDER 1. Rhizomastigida

• Animals in this order are small and like amoeba.
• In this, animals have one to four flagella.
• These animals move using flagella or pseudopodia.
• Mainly it is found in clean water.

Examples – Mastigamoeba, Dimorpha.

ORDER 2. Kinetoplastida

• Animals in this order are more or less like small amoebas.
• One or two flagella are found in these.
• Their nutrition is holozoic or saprozoic.
• These are solitary or colonial animals.
• These animals live in the blood as parasites.

Examples – Leishmania, Trypanosoma, Bodo.

ORDER 3. Choanoflagellida 

• Free-living animals live in this group.
• These are colonial.
• A flagellum has a collar around its base.
• Their nutrition is of Holozoic type.

Example – Proterospongia.

ORDER 4. Diplomonadida

• These animals are small and have a delicate pellicle and a cytostome.
• They have 3 to 8 flagella which form the border of a wavy membrane.
• There is one nucleus in them, sometimes there are more nuclei also.
• Mainly these are parasites living in the intestine.

Example – Giardia, Hexamita.

ORDER 5. Hypermastigida

• Organisms with more flagella have been placed in this order with higher characteristics.
• Their kinetostomes or parabasal bodies are in a circular longitudinal or curved row.
• These are organisms with one nucleus or multiple nuclei.
• These animals do not have a mouth, they eat food through pseudopodia.
• These are parasites found in the intestines of cockroaches and termites.

Example – Triychonympha, Lophomonas.

ORDER 6. Trichomanadida

• 4 to 6 flagella are found in these animals.
• They also have flagella for moving backward.
• These parasites are found in the genital tract.

Example – Trichomonas

Superclass (B). Opalinata

• The body of organisms in this superclass is covered with flagella or cilia.
• Nuclei are more than two and monomorphic.
• Their nutrition is saprozoic type.
• In these, reproduction takes place through binary fission or gametes.
• These parasites are found in frogs and toads.

Example – Opalina.

Superclass (C) Sarcodina (=Rhizopoda)

• Their body is without pellicle.
• They move by Pseudopodia.
• Their nutrition is holozoic or saprozoic.
• In these, asexual reproduction occurs through binary fission.
• They are solitary and free-living, some are parasitic or colonial.

Class 1. Actinopodea

Pseudopodia are axopodia with axial filaments radiating from the spherical body.

Subclass (1) Heliozoa

• These are spherical protozoans.
• Pseudopodia (axopodia) are radiating.
• Their body is naked and the outer part is differentiated into vacuolated ectoplasm and the inner part is solid endoplasm.
• Their nutrition is of Holozoic type.
• Most of the animals live in freshwater.

Example – Actinophrys, Clathrulina Actinosphaerium.

Subclass (2) Radiolaria

• Their perforated central capsule separates the ectoplasm from the endoplasm.
• There is no contractile vacuole in these.
• These are in the form of pseudopodia, axopodia or filopodia.
• Their skeleton is sharp like silica.
• These are marine.

Example – Collozoum.

Subclass (3) Proteomyxidia

• These have pseudopodia in the form of filopodia.
• They live in seawater or clean water.
• In these, reproduction takes place through binary fission or multiple fission.

Example –Pseudospora

Subclass (4) Acantharia

• The central capsule is non-chitinous and without pores.
• Their skeleton is made of Strontium sulphate.
• Pseudopodia in these is in the form of axopodia.

Example – Acanthrometra

 Class 2. Rhizopodea

• These include pseudopodia, lobopodia, filopodia. Or in the form of reticlopodia and it is without axial fiber.

Subclass (1) Lobosia

In these, Pseudopodia is in the form of Labeopodia.

ORDER 1. Amoebida

• Their body is like that of an amoeba and they are without a skeleton.
• In these, pseudopodia (lobopodia) are small and the end is also blunt.
• Ectoplasm and endoplasm are different.
• Most live in clean water and some are parasites.

Example – Amoeba, Entamoeba  

ORDER 2. Arcellinida (=Testacida)

• Their body is enclosed in an orbital shell
• This shell has a single hole through which the lobopodia protrude.
• They are free living and are found in clean water.

Examples – Arcella, Difflugia, Euglypha.

Subclass (2) Filosia

• This subclass contains pseudopodia, filopodia, it is thin and long and has branches.
• Their body is naked or with a shell with a hole in it.
• Ectoplasm is not separated in this.
• They live in seawater or clean water.

Examples – Allogromia, Penardia.

Subclass (3) Granuloreticulosia

It contains pseudopodia in the form of reticulopodia.

ORDER Foraminiferida

• In this, the animals are large and have one or multiple chambered shells.
• There are one or more holes along the shell through which reticulopodia emerge.
• These are mainly marine.

Example – Globigerina, Elphidium (=Polystomella)

Subclass (4) Mycetozoia

• Their body is long, amoeboid, meaning like amoeba and they are multi-nucleated.
• There are many pseudopodia and they are obtuse.
• Contains spores in the form of sporangia.

Example – Slime molds.

Class 3. Piroplasmea

• These are small parasites and are found in the red blood cells (RBCs) of vertebrates.
• These are not in the form of spores.

Example – Babesia

• Now we will learn completely about the second subphylum Sporozoa of Phylum Protozoa.

Subphylum II. SPOROZOA

• Only endoparasites have been kept in this subphylum.
• Their body is thick and along with this, their pellicle is also thick. Adults do not have organs to walk or move.
• The nutrition in these is saprozoic.
• In these, asexual reproduction occurs by multiple fission and sexual reproduction occurs by spore formation after gamete fusion.
• Their life cycle includes both sexual and asexual stages.

Class 1. Telosporea

• Spores are without polar sheaths or filaments.
• In this, sporozoites are rigid and microgametes are flagellated.
• It has only one nucleus with trophozoites.

Subclass (1) Gregarinia

• In this, trophozoites are long and are found in the body cavity and alimentary canal of invertebrate animals.
• Gametes show syzygy.
• Zygotes are immobile, that is, they cannot move.
• Sporozoites are found in sporocyst.
• Male and female gametes are monogamous.
• These are parasites found in invertebrates.

Examples – Monocystis, Gregarinia, Nematocystis.

Subclass (2) Coccidia

• Trophozoites are small and intracellular.
• In this the gametes are dimorphic.
• Spores are in sporocysts (oocysts).
• These parasites are found in the intestine or alimentary canal of vertebrates.

Example – Eimeria, Isospora Plasmodium.

Class 2. Toxoplasmea

• Spores are not formed in this class of organisms.
• In these only asexual reproduction takes place.

Example – Toxoplasmea

Class 3. Haplosporea

• It contains spores along with spores.
• These parasites are found in fish and invertebrates.
• Pseudopodia may be present in these but flagella are not present.
• In these, reproduction occurs only through schizogony (asexual).

Examples – Ichthyosporidium, Haplosporidium.

Now we will study completely step by step the third suborder of Phylum Protozoa.

Subphylum III. CNIDOSPORA

• Trophozoites contain multiple nuclei.
• In these, spores are produced throughout life.
• Spores also contain polar filaments along with the polar shell.

Class 1. Myxosporidea

• In this group, spores develop in the form of many nuclei.
• There are two or three valves inside the spore.

ORDER 1. Myxosporida

• These spores are larger and have a bivalve membrane.
• There are 1,2, or 4 polar capsules. Each is accompanied by a filament.
• Trophozoites are amoeboid

Example – Myxidium

ORDER 2. Actinomyxida

• In this also the spores are larger and have a trivalve membrane along with them.
• There are 3 polar capsules and each has a filament.

Example – Triactinomyxon, Sphaeractinomyxon.

Class 2. Microsporidia

• In this, the spores are small and have a valve membrane.
• They may or may not have polar capsules.

Example – Nosema

Subphylum IV. CILIOPHORA

• The body of organisms of this subclass is complexly organized.
• Cilia for eating and in some stages of the life cycle it is present as an organ for walking or locomotion.
• Two types of nuclei are present in it, micronucleus and macronucleus.
• In these, asexual reproduction occurs by double fission or budding.
• Sexual reproduction occurs by chance.

Class 1. Ciliata (Infusoria)

• Along with these protozoa, they have a definite form and size.
• Their body is surrounded from the outside by a hard pellicle.
• They have cilia as the organ for walking.
• In these, the mouth (cystostome) and pharynx are present and an anal opening (cytopyge) is always present in them.
• One or more contractile vacuoles are found in these organisms.
• They have two types of nuclei, large macronucleus and small micronucleus.

Subclass (1) Holotrichia

• Body cilia are in one form.
• They do not have mouth cilia.

ORDER 1. Gymnostomatida

• Their body is big.
• Buccal cilia are not found in these.
• The cytostome is open from the outside.

Examples – Coleps, Didinium, Nassula.

ORDER 2. Trichostomatida

• The cytostome is at the bottom of the vestibule.
• There are spiral rows of cilia in the vestibule and there are no cilia in the mouth area.

Example – Colpoda, Balantidium.

ORDER 3. Chonotrichida

• The body of the creatures of this order is pitcher-shaped.
• There are no cilia in their body.
• Vestibular: The last free end of the body is funnel-shaped with cilia.
• Crustaceans have external commensalism.

Example – Lobochona, Spirochona.

ORDER 4. Apostomatida

• The body of organisms of this order is arranged spirally with cilia.
• The cytostome is in the middle abdomen.
• The life cycle of a parasite or commensal is complex. Their life is completed in two hosts or nurturers.

Example – Hyalophysa, Polyspira.

ORDER 5. Astomatida

• The cytostome is not found in the organisms of this order.
• Their body is ciliated and homogeneous.
• These parasites or commensals are found in the alimentary canal and coelom of earthworms.

Example – Anoplohyra, Hoplitophyra.

ORDER 6. Hymenostomatida

• Apart from having small bodies, the creatures of this order also have uniform cilia on their body.
• The membrane cells have an oral cavity with a canal area and a wavy membrane.

Examples – Copidium, paramecium, Tetrahymena.

ORDER 6. Hymenostomatida

• In this subclass, the body of the adult organism is without cilia.
• The end of the head has a mouth with cilia.
• These organisms are sessile organisms.

Examples – Copidium, paramecium, Tetrahymena.

Subclass (2) Peritrichia

• In this subclass, the body of the adult organism is without cilia.
• The end of the head has a mouth with cilia.
• These organisms are sessile organisms.

ORDER 1. Peritrichida

• This order has the characteristics of subclass peritrichia.

Examples – Vorticella, Carchesium.

Subclass (3) Suctoria

• The body of organisms of this subclass is both stalked and sessile.
• Cilia are found in the young and tentacles are found in the adult.

ORDER 1. Suctorida

• Characteristics of subclass Suctorida are found in this order.

Example – Ephelota, Podophrya.

Subclass (4) Spirotricha

• Organisms of this subclass have fewer cilia in their body.
• In these organisms, the oral cilia are well-marked.

ORDER 1. Heterotrichida

• Their body is attached to the lorica.
• They mainly do not have cilia in their body.
• Their body is naked and the body cilia are uniform.

Examples – Bursaria, Stentor, and Blepharisma.

ORDER 2. Hypotrichida

• Their body is flattened towards the dorsal-ventral side.
• Body cilia on the ventral side form cirri.

Example– Euplotes, Kerona.

ORDER 3. Oligotrichida

• Body cilia are less or absent in these.
• The mouth is membranous only at the front end.

Examples – Strombidium, Halteria.

Conclusion –

Friends, we have learned about the Phylum Protozoa, and its subphylum, superclass, class, order, and characteristics.

So, friend, I hope that you have liked the given information about phylum protozoa. If you liked this article then share it with your friends.

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