Characteristics of Protist Kingdom

Each kingdom groups organisms with similar characteristics whether they are visible or not. The groups of plants, animals and fungi are often easily differentiated from each other, but in the case of protists differentiation is not so simple.

This kingdom contains mainly unicellular organisms but the totality of its members is eukaryotic. It is also known as the Protoctist realm .

The only thing that protists usually have in common is that they are not animals, they are not plants, they are not fungi and many are unicellular.


It is a very diverse kingdom. The only thing that protists usually have in common is that they are not animals, they are not plants, they are not fungi and many are unicellular.

1. Although most protist organisms are unicellular , others are multicellular without specialized tissues and no type of cell differentiation.

2. Its nuclei are surrounded by a nuclear membrane.

3. Some protists form colonies, but they are not organized in such a way that they form tissues.

4. Many protists are aquatic organisms.

5. They can reproduce sexually or asexually through gametes or binary fission .

6. They show movements according to their locomotion structures. In this sense, they can be flagellated (with flagella), with pseudopods and ciliates (with cilia).

7. Maintain varied nutrition methods that include filtration and phagocytosis .

The best-known protists are amoebas, unicellular living beings that lack definite shape. They are fed by phagocytosis but their popularity is due to their condition as parasites in the intestines of the members of the Animalia kingdom .


Traditionally protozoa, some algae and myxomycetes have been considered protist organisms. But it is important to consider that there is no universally accepted classification, since it varies according to the author. Sometimes all algae are considered to be protists while other classifications make a separation between green algae as plants, blue-green algae as members of the Monera kingdom and other algae of the Protista kingdom.


From this complicated perspective, the Protista kingdom can be divided into:

Protozoa Protozoa or protozoa are unicellular, eukaryotic and heterotrophic organisms found in aquatic or humid habitats. Almost all are microscopic and your body may be surrounded by a membrane of secretion located above the plasma membrane.

According to their forms of locomotion are:

Flagellates . They have one or more flagella, that is, whip-like structures. Some flagellated protozoa are parasites.

Ciliates . Organisms with numerous cilia, structures that resemble hairs.

Rizópodos . They are a kind of false feet that are called pseudopods.

Sporozoans . They are microscopic organisms that parasitize animals.

Myxomycetes . Some scientists classify them in the Fungi kingdom . Most of these organisms are saprophytes but others are parasites.

These protists reproduce by means of spores, are fed by phagocytosis and move with the help of pseudopods. They are commonly known as mucilaginous molds and, like many myxomycetes, have a body similar to those of amoebas; they are also called amoeboid mushrooms.

They are devoid of photosynthetic pigments and reproduce sexually or asexually.

Seaweeds . These organisms perform a process of photosynthesis. Usually green algae that have much in common with terrestrial plants are outside this group, but other classifications include all of them.

Although it may seem that algae are only found in aquatic habitats, the truth is that they are capable of thriving in any habitat, from seas to bark.

They are usually classified according to their photosynthetic pigments. Thus, there are brown algae, red algae, yellow algae and green algae.

Oomycota (Oomycetes). They are known as aquatic molds because of their resemblance to members of the Fungi kingdom. They are nourished by absorption and reproduce sexually and asexually. Many oomycetes are parasites and others are saprophytes.

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