Dictionary > Protozoa

Protozoa

Definition
noun, singular: protozoon
Eukaryotic organisms belonging to a group characterized for being single-celled, most of them motile and heterotrophic
Supplement
In a five-kingdom scheme of classifying organisms, Protozoa belongs to a taxonomic group within Kingdom Protista, and typically divided on the basis of their means of locomotion:

  • Flagellates – protozoans that make use of flagella for locomotion, (e.g. Giardia lambdia)
  • Amoeboids – protozoans with temporary body projections called pseudopods, (e.g. Entamoeba histolytica)
  • Sporozoans – protozoans that lack locomotory apparatus and therefore are generally non-motile, (e.g. Plasmodium knowlesi)
  • Ciliates – protozoans that have ciliates, (e.g. Balantidium coli)

The former four subphyla used to classify protozoans based on locomotion are as follows: (1) subphylum Sarcomastigophora (includes a superclass of flagellates Mastigophora, superclass Sarcodina, and superclass Opalinata), (2) subphylum Sporozoa (includes the sporozoans), (3) subphylum Cnidospora (includes microsporideans, and (4) subphylum Ciliophora (includes the ciliates). This system of classification though is no longer as popular as it was since recent methods used as basis for classification involves DNA sequences. Furthermore, the use of the term protozoa is now discouraged and Protista or protists are preferred.
Word origin: from Greek protohi = first and zoa = animals
See also:

Related term(s):

  • protozoan (noun or adjective)
  • protozoic (adjective)
  • protozoal (adjective)


  • You will also like...

    Stem
    Stems

    Stems primarily provide plants structural support. This tutorial includes lectures on the external form of a woody twig ..

    Plant biology
    Plant Biology

    Plantlife can be studied at a variety of levels, from the molecular, genetic and biochemical level through organelles, c..

    Physiological Homeostasis
    Physiological Homeostasis

    Homeostasis is essential to maintain conditions within the tolerable limits. Otherwise, the body will fail to function p..

    Endemic Flora of New Zealand
    New Zealand’s Unique Flora

    If New Zealand has lots of unique animals, it's also got a whole lot of unique plants. Find out more about some of them,..

    Energy pyramid
    Freshwater Community Energy Relationships – Producers & Consumers

    This tutorial looks at the relationship between organisms. It also explores how energy is passed on in the food chain an..

    DNA carries genes coding for proteins
    Genetic Information and Protein Synthesis

    Genes are expressed through the process of protein synthesis. This elaborate tutorial provides an in-depth review of the..

    Related Articles...

    No related articles found

    See all Related Topics