Phylum Protozoa: General characteristic and classification




General Characteristics of phylum Protozoa

  1. Kingdom: Protista.
  2. They are known as acellular or non-cellular organism. A protozoan body consists of only mass of protoplasm, so they are called acellular or non-cellular animals.
  3. Habitat: mostly aquatic, either free living or parasitic or commensal
  4. Grade of organization: protoplasmic grade of organization. Single cell performs all the vital activities thus the single cell acts like a whole body.
  5. Body of protozoa is either naked or covered by a pellicle.
  6. Locomotion: Locomotory organ are pseudopodia (false foot) or cilia or absent.
  7. Nutrition: Nutrition are holophytic (like plant) or holozoic (like animal) or saprophytic or parasitic.
  8. Digestion: digestion is intracellular, occurs in food vacuoles.
  9. Respiration: through the body surface.
  10. Osmoregulation: Contractile vacuoles helps in osmoregulation.
  11. Reproduction:
  • Asexually reproduction is through binary fission or budding.
  • Sexual reproduction is by syngamy conjugation.

Classification of Protozoa:

  • Phylum protozoa is classified into four classes on the basis of locomotary organs

Class 1 Rhizopoda

  • Locomotary organ:
  • Mostly free living, some are parasitic
  • Reproduction: asexually by binary fission and sexually by syngamy.
  • No conjugation.
  • Examples: Amoeba, Entamoeba

Class 2 Mastigophora/ Flagellata

  • Locomotory organ: Flagella
  • Free living or parasite.
  • Body covered with cellulose, chitin or silica.
  • Reproduction: A sexual reproduction by longitudinal fission.
  • No conjugation.
  • Examples: Giardia, Euglena, Trypanosoma

Class 3 Sporozoa

  • Locomotory organ: Absent
  • Exclusively endoparasites
  • Contractile vacuoles is absent
  • Body covered with pellicle.
  • Reproduction: Asexual reproduction by fission and Sexual reproduction by spores
  • Examples: Plasmodium, Monocystis

Class 4 Ciliata

  • locomotary organ: Cillia
  • Body covered by pellicle.
  • Reproduction: Asexual reproduction by binary fission. Sexual reproduction by conjugation.
  • Nuclei two types i.e. macronucleus and micronucleus.
  • Examples: Paramecium, Voricella, Blantidium

Phylum Protozoa: General characteristic and classification