Protozoa।It’s classification and features

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Hello reader, this article is all about Protozoa.

Here I will discuss about :

  • Introduction to Protozoa
  • Etymology of the term
  • Characteristics
  • Classification of Protozoa

Introduction :

R.H .Whittaker first divided all living organisms in five (5) kingdoms. This is known as Five Kingdom Classification. These 5 kingdoms are Protista, Monera, Fungi, Plantae and Animalia.

Organisms of Protista kingdom are unicellular organisms with eukaryotic type of cellular organisms.

Goldfuss first used the term Protozoa which contains more than ~80,000 species. Some well known protozoan organisms are Plasmodium vivax, Plasmodium falciperum, Entamoeba Sp. Amoeba Sp. etc

Their locomotory organs are mainly cilia or flagella. Based on their cellular size, habit and habitat, nutrition and locomotion, protozoa Sub-kingdom has been further divided into several Phylums. However many classifications have been done by different scientists, classification of Levine at al.(1980) is most accepted. According to this classification, Protozoa Sub-Kingdom has been divided into seven(7) different Phylums.

Etymology

The term Protozoa is derived from the Greek word protos which means primitive or first and zoon which means animal.

Characteristics

  • Protozoa are solitary individuals and a number of them are colonial.
  • They may be free living, commensals, mutualistic and parasitic.
  • They are usually microscopic, possessing typical membrane bound cellular organelle.
  • Locomotary organ include flagella, cilia or flowing extensions called pseudopodia.
  • Nutrition may be holozoic, holophytic, saprophytic or parasitic.
  • Reproduction commonly performed by asexual reproduction, i.e. Binary fission.
Classification of Protozoa

Phylums under Subkingdom Protozoa

Subkingdom Protozoa is divided into seven phylum.

  • Sarcomastigophora
  • Labyrinthomorpha
  • Apicomplexa
  • Microspora
  • Acetospora
  • Myxozoa
  • Ciliophora

The first phylum under Protozoa( Subkingdom): Sarcomastigophora

Features:

  • Nucleus is of one type.
  • Locomotory organs are either pseudopodia or flagella or both.
  • Reproduction asexually but when sexually it is essentially by syngamy.

Examples : Volvox sp., Leishmania sp., Opalina sp., Amoeba sp., Elphidium sp. sp.

Volvox sp. (Sarcomastigophora)
Volvox sp. , Amoeba sp.
Amoeba sp. (Sarcomastigophora)

Phylum : Labyrinthomorpha

Features:

  • Mostly inhabitants of marine ine and esturine water.
  • Trophic stage having ectoplasmic network with spindle shaped non amoeboid cells.
  • In some general amoeboid cells move within the cytoplasmic network by gliding
  • Saprophytic and parasitic on algae
  • Zoospores are produced by most species

Examples : Labyrinthula sp., Labyrinthomyxa sp.

Phylum : Apicomplexa

Features:

  • All species are parasitic in nature.
  • Anterior part of the body forms apical complex.
  • Microspores are generally present at some stage.
  • They reproduce sexually by syngamy.

Examples: Monocystis sp., Plasmodium sp.

Phylum : Microspora

Features:

  • Intracellular parasites found nearly all major animal groups.
  • Spores unicellular, each with imperforated wall, containing one uninucleate or dinucleate sporoplasm.
  • Spore is with simple or complex extrusion apparatus associated with polar tube and polar cap.
  • Mitochondria absent in spores.
  • Usually dimorphic in sporulation sequence.

Example: Nosema sp.

Phylum : Acetospora

Features:

  • In most of the cases the spores are multicellular.
  • Spores with one or more sporoplasm.
  • Spores without polar capsules for polar filaments.
  • All are parasitic.

Example : Haplosporidium sp. , Paramyxa sp.

Phylum : Myxozoa

Features:

  • spores are of multicellular origin with one or more polar capsules and sporoplasms.
  • Each spore with one , two or three valves.
  • All species are parasitic.

Example : Myxidium sp. , Trilospora sp.

Special Credit goes to my class mate : Debapriya Maity

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