Classification of PROTOZOES

The protozoa They are microorganisms unknown to most people, but they are very important to the health of our ecosystem and for human health, as they can cause very dangerous diseases and even lethal.

Protozoa are beings eukaryotes and heterotrophs, but within this group we can find very different microorganisms. To study them, scientists have made a classification based on their way of life. In this lesson from a TEACHER we will see the classification of protozoa, We invite you to continue reading!

Index

1. What are protozoa? How are they classified?
2. Rhizopods or Sarcodinos
3. Sporozoa
4. Ciliates, another type of protozoa
5. Flagellates or Mastigophores

The protozoa are microscopic organisms, formed by single cell (unicellular), eukaryoticY heterotrophs. One of the most surprising characteristics is that, despite being relatively simple microorganisms, found in almost all habitats, either as free-living organisms or as parasites of plants or animals of all kinds.

To study them in a simple way, the scientists devised a classification. When looking at them under the microscope, they realized that protozoa, wherever they lived, could be forced to be parasites and to live and feed inside cells or have free life, and move generating different appendages: pseudopods, cilia or flagella. Based on this, they made a simple classification of the protozoa.

We begin this classification of protozoa by talking about rhizopods, very simple protozoa whose main characteristic is that they move through pseudopods, which is a simple extension of the cytoplasm, which the organism is taking out and putting in. This generates that these microorganisms have a very characteristic type of displacement, in which they seem to be crawling: amoebic displacement. This displacement that is also typical of other organisms or cells such as macrophages.

Rhizopods are organisms formed by a cytoplasm with a nucleus and non-permanent organelles, which appear at certain times in their life cycle. Some groups such as foraminifera or radiolaria have a hard external protective structure called teak.

In this group, free-living individuals appear as Amoeba proteus or Nummulites and parasites, some of which cause disease (such as Entamoeba histolytica, which produces amoebic dysentery) or not (Entamoeba gingivalis, which lives in a non-pathogenic way in our mouth).

Image source: Biology 1st of ESO

Sporozoa are immobile protozoa, that is, they are unable to move. That is why they live inside cells, body cavities or body fluids. They normally attack all kinds of animals causing very serious diseases and are especially dangerous because some are capable of forming very resistant spores.

Only a few species of the more than five thousand extant species have been found to cause disease, but some like the malaria (Plasmodium malarie Y Plasmodium Falciparum) wave toxoplasmosis (Toxoplasma spp) generate a large number of deaths worldwide.

Ciliates are the most evolved group of protozoa since they present more developed structures of locomotion: the cilia. Cilia are small extensions of the cytoplasm that are distributed throughout the cell membrane or in specific locations (for example, in some microorganisms they are found around the mouth, and are called cilia peristomatic). The cilia serve for the displacement of the individual in most cases but they can also serve for the capture of food in predatory ciliates.

The internal structure of the ciliates is the most complex of all protozoa: they contain a region of the cell specialized in taking food and digesting it (cytostomy and cytopharynx) and another in charge of eliminating waste (cytopygium). The reproduction of this group is also somewhat peculiar since these organisms have a macronucleus, which is responsible for the control of the cell, and a micronucleus that is in charge of carrying out the sexual reproduction characteristic of the group.

Some examples of ciliated organisms within the classification of protozoa are: paramecia (Paramecium spp), Didinium spp, Dileptus spp, etc. These organisms, which can be found free in fresh or salty waters, can have different feeding strategies and some of them can even become voracious predators.

Image: Slideplayer

The flagellates are considered the oldest group of protozoa. They are characterized by moving by means of flagella. They can live freely, in fresh or salt water and be singly or in colonies. It should be noted that the formation of colonies does not imply that it is a multicellular organism, since each of the cells that form the colony continues to maintain its individuality and if it is separated from the rest of the colony, it can continue to live fully normal.

The flagellates best known are those of free life. Some examples are: Volvox spp, Gonyaulax catenella (which forms colonies and causes the "red tide"), Noctiluca scintillan (commonly known as sea spark)

There are also parasitic groups within the flagellates, among them the following can be highlighted: Trypanosoma gambiense Y Rhodesian trypanosome (that cause sleeping sickness), Trypanosome cruzi (which produces Chagas disease), Leishmania spp (causing serious diseases such as Kala-azar or black fever), etc.

If you want to read more articles similar to Classification of protozoa, we recommend that you enter our category of biology.

• Hickman, C. P., Roberts, L. S., Larson, A., Ober, W. C., & Garrison, C. (2001). Integrated principles of zoology. McGraw-Hill.
• Biosphere Project. Ministry of Education; Government of Spain (s.f) Protozoa. Recovered from: http://recursos.cnice.mec.es/biosfera/alumno/2bachillerato/micro/contenidos7.htm
• Pumarola, A., Rodriguez-Torres, A., Garcia-Rodriguez, A. & Piedrola-Angulo, G. (1987). Microbiology and Medical Parasitology. Masson.