Question

How many types of protists are there?

Answer 1

The given term ‘Protista’ is derived from the region Greek word “protistas”, which means “the very first“.
Protists are eukaryotic organisms that neither belong to the plant kingdom nor animals or fungi. They are unicellular organisms but can also be present as a colony of cells.
They sometimes live as parasites but most of the time in water, damp terrestrial environments.

Complete answer:
These organisms are usually unicellular and the cell of these organisms contains a nucleus that is bound to the organelles. Some of them possess’ flagella or cilia that help in locomotion
The kingdom of protists consists of several organisms-
Protozoans- they are unicellular organisms parasitic in nature that live on larger organisms.
Protozoans cannot change their shape but have a predefined shape.
Examples of protozoans are amoeba, paramecium, and euglena.

The protozoans can further be categorized as-
-Amoeboid protozoans: They are found in fresh or saline water bodies and have pseudopodia (false feet) which help them to change their shape and in capturing and engulfing food. Example- Amoeba
-Flagellated protozoans: They are a group of protozoans having flagella and can be free-living or parasitic. Example-Euglena
-Ciliated protozoans: They are ciliated, that is they have cilia all over their body and they live in water. It helps them in locomotion as well as nutrition. Example- Paramecium
-Sporozoans: They are organisms having a spore-like lifecycle. Example- the malarial parasite, Plasmodium.

Slime moulds: They feed on the dead and decaying matter, which means they are saprophytic. These are small organisms that have numerous nuclei.
-Chrysophytes are photosynthetic organisms characterized by the presence of a hard siliceous cell wall. The accumulation of cell wall deposits forms the diatomaceous earth. Example- diatoms and golden algae.
-Dinoflagellates are photosynthetic organisms that are found in different colours, according to the pigment present in them. They show bioluminescence and are known to cause red tide.
-Euglenoids act as the linkers between plants and animals. They lack a cell wall but perform photosynthesis. Example- Euglena, Trachelomonas, etc.

Note: Scientists believe that protists form a link between plants, animals, and fungi. All the three kingdoms diverged from a common ancestor protist. Though this theory is hypothetical, still some genes found in modern animals and plants can be traced to these ancient organisms. Therefore they are important kingdoms of the five kingdom classification.