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The Protista kingdom or the kingdom of protists or protoctists, one of the great kingdoms of nature, hides an endless number of organisms and life forms of the most intriguing and peculiar. Despite those first scientific discoveries about the Protista kingdom, we now know that protists are not considered mini-plants or mini-animals, nor are they considered a combination of both. Protists have very specific distinctive characters, as well as well-defined habits and life cycles. Around 120,000 species of these fascinating organisms are currently considered to be members of the Protista kingdom, including algae, fungi, protozoa, and other less common and abundant groups of living things.
Continue reading this interesting article by Ecologist Verde if you want to learn about the Protista kingdom: what is it, characteristics, classification and examples and, in addition, you will be able to see several images of the Protista kingdom.
What is the Protista kingdom - simple definition
We start by explaining what is the Protista kingdom, before going into details about its characteristics, classification and other aspects. The Protista or protoctist kingdom appeared as the third of the five great kingdoms of living beings in nature (Animalia or animal kingdom, Plantae or vegetable kingdom, Protista or Protista kingdom, Fungi kingdom or fungi kingdom. and kingdom Monera or monera). But, what exactly does the Protista kingdom include? Included in this realm are all those unicellular and multicellular eukaryotic organisms with intermediate anatomical and functional characteristics between plants and animals.
Going unnoticed and being great unknown of the incredible biodiversity that nature hides, protists fill with micro and macroscopic life many of the corners of the planet, from the ecosystems of fresh and salt water, as well as on the humid earth and, even, as parasites of animals. In the next sections we will learn more about these mysterious and fascinating organisms, the protists.
What are the characteristics of the Protista kingdom
Between the main characteristics of the kingdom Protistas stand out:
- Is about eukaryotic organisms (with a nucleus delimited by a membrane), lacking differentiated vegetative tissues, except in those structures destined to the reproduction process.
- The size of the protists is highly variable, from microscopic unicellular forms, until multicellular organisms several meters long.
- They are found in a wide variety of places: soil, fresh water, ocean floor, decomposing organic matter, etc.
- In the kingdom of the protists, all possible nutrition models are exhibited: autotrophic (phototrophic) and heterotrophic, through phagotrophic, saprobiotic or parasitic strategies.
- They present a great variety of types of locomotion, by means of flagella, cilia and pseudopods; although there are also numerous species that lack mobility. Many organisms are free-living, while others have symbiotic relationships (mutualistic, commensal, or parasite).
- Some species of the Protista kingdom have developed the amazing ability to form, during their life cycles, resistance structures (called cysts) in periods of unfavorable conditions such as lack of water and food, thus surviving in a dormant state (stopping their metabolic functions), until more favorable conditions for their reproduction and survival arrive. In addition, they are capable of forming spores in those stages of the life cycle that guarantee their multiplication and propagation.
- The reproduction in protists it is governed by different reproductive strategies, such as asexual reproduction through mitosis, bipartition, budding or multiple division; as well as sexual reproductive activity with mitotic and meiotic processes. Learn more about these reproductive processes with this other article on the Difference between mitosis and meiosis.
Classification of the Protista kingdom
The complex and diverse characteristics of protists or protoctists they make their classification one of the most difficult and convoluted in the evolution of living beings. Many have been the scientists who throughout history have tried to determine a classification for the Protista kingdom as successful as possible. At present, the different protists are classified into the following supergroups:
- Amebozoa: amoebae, slime molds and myxomycetes.
- Archaeplastida: red algae (Rhodophyta)
- Excavate: Flagellated organisms of the Euglenozoa and Percolozoa groups.
- Stramenopiles: brown algae, diatoms, chrysophyceae and xanthophyceae.
- Alveolata: ciliated organisms, dinoflagellates and apicomplexes.
- Rhizaria: foraminiferous, radiolarian and cercozoan microorganisms.
- Opisthokonta: metazoans with differentiated tissues, fungi, choanoflagellates and Mesomycetozoa.
In the next section we will see some examples of protist species to better understand what name and appearance these mysterious living beings have.
Examples of the Protista kingdom
After knowing all this, we still wonder what are the organisms that belong to the protist kingdom, so here we summarize that some of the main genera and most representative species to give examples from the Protista kingdom or examples from the protoctists are:
- Laminaria digitata (large laminar brown algae, reaches two meters in length)
- Genus Sargassum ("Sargasso", brown macroalgae several meters long)
- Genus Chlamydomonas (freshwater unicellular green algae)
- Genus Ulva ("sea lettuce" alga)
- Trypanosoma cruzi (produces chagas disease)
- Entamoeba histolytica (intestinal parasite)
- Balantidium coli (produces Balantidian dysentery)
- Paramecium caudatum (free-living protozoan)
- Plasmodium vivax (produces malaria)
- Giardia lamblia (intestinal parasite)
- Trichomonas vaginalis (vaginal parasite)
Here you can see images of the Protista kingdom (These are some of the species on this list of examples of protists).
Importance of the Protista kingdom
The diverse kingdom of the protists had, from its origin, a great importance within the world of scientific taxonomy and biology, among other branches of science. Although today articles and studies refer to it as the Protista ("primordial") kingdom, the scientist Margulis tried to give them the importance they deserved by choosing the name of "Protoctista kingdom" (from the Greek "first creatures"), thus highlighting its relevance in the knowledge of the evolution of living beings.
As we have been discovering in the previous sections of this article, protists play a really important role in the functioning of different ecosystems, as well as in the world of medicine, since many of these organisms are the cause of some of the most dangerous diseases that affect humans.
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Bibliography- López-Ochoterena, E. (1991) Advances in the taxonomy of protists. Biological taxonomy, Fondo de Cultura Económica, Mexico, pp: 2-8.
- Alder, V. A. (2014) Marine protists. Félix de Azara Natural History Foundation, Argentina, pp: 354.
- Burki, F. (2014) The eukaryotic tree of life from a global phylogenomic perspective. Cold Spring Harbor Perspectives in Biology. Volume 6, pages: 1-17.
