Protozoa

Our Earth has millions and millions of living creatures that include both micro-organisms and macro-organisms. Microorganisms are minute in structure and most of them are not visible to naked eyes. We could only see them using a scientific microscope. Bacteria, viruses, algae, fungi, etc are some examples of microorganisms. 

Protozoa are also known as ‘single-celled animals’ in ancient days because they have characteristics of animals such as predation. It was first introduced in 1818 by Scientist Georg Goldfuss. Amoeba is an example of protozoa that is also present in our human body. Let us read more about Protozoans!

What are Protozoans?

Protozoans are single-celled organisms that are present in different shapes, forms, and sizes. These organisms live in a wide variety of moist regions that include clean water surfaces, ocean environments, and moist land areas. Protozoa is a group of single-celled eukaryotes that can alter its fixed shape into a complex structure called Paramecium. 

History of Protozoa

Protozoan was first discovered by Dutch Microscopist Anton Van Leeuwenhoek in 1818. He witnessed protozoa as well as bacteria using a microscope with simple lenses. Since the discovery, protozoa have experienced different stages of evolution so far. The early protists (protozoa) were likely to have an amoeboid structure.  

Types of Protozoans

Protozoa can be broken down into four different categories namely Amoeba, Flagellates, Ciliates, and Sporozoa.

Amoeba – It is a popular uni-celled organism that possesses the ability to change its shape by expanding and retracting its pseudopods. Amoeboid has a structure of a tiny globule of colourless jelly that has a dark speck within it.

Flagellates – These are uninucleate organisms that can cause high infectious diseases like Giardia. Flagellates have a hair-like structure that helps them perform locomotive actions.

Ciliates – It has a similar hair-like structure to eukaryotic flagellates. Ciliates contain two variations of nuclei inside one cell.

Sporozoa – These are the complex protozoans with both asexual and sexual generations. Sporozoa do not have any locomotive features like flagellates. So, they rely on bending, gliding, and twisting to move from one place to another.

General characteristics of Protozoan 

Protozoa is a eukaryotic microorganism that is referred to as a part of the microbial world. It plays a major role as Zooplanktons which contributes a lot to various food chains and food webs. All protozoa share some of the general characteristics given as follows. 

• Most of them live in moist areas like water bodies
• They do not have a rigid cell wall 
• They are present in various shapes and sizes (both microscopic and macroscopic)
• They are heterotrophic microorganisms 
• Most protozoans can perform locomotion except Sporozoa
• They can survive even the hardest conditions by relying on other organisms 

Some example of Protozoa

Ceratium, Glenodinium, Navicula, Melosira, Cymbella, Eutreptia, Phacus, Euglena, Physarum, Physarella, Amoeba, Giardia, Plasmodium, Leishmania, and Trypanosoma are some of the examples of protozoa.  

Diseases caused by Protozoans

Protozoa is considered the ’first animals,’ meaning they are the first creature that formed on earth. Protozoans are not visible to naked eyes except for a few of them. Due to their minute structure, they can easily enter the human body and can cause infectious diseases. 

Here are some diseases caused by Protozoa.

• Malaria
• Chagas disease
• Lambliasis
• Amoebiasis
• Cryptosporidiosis
• Toxoplasmosis
• Blastocystosis

Let us have a quick look at some of these diseases in detail. 

Amoebiasis- It is a disease that causes irritation to the bowel and leads to amoebic dysentery. In most cases, it occurs due to poor sanitation or even a change in the climate. Fever, abdominal pain, loss of appetite, nausea, and bloody stool are some of the symptoms of amoebiasis.

Malaria- It is widespread and one of the deadly diseases around the world. Mosquitos are the primary carriers of these harmful protozoans. Vomiting, fever, headache, cough, muscle pain, and abdominal pain are some of the symptoms of malaria. In worst cases, it can also cause organ failure and other severe health threats.

Giardia – It is a diarrheal infection that is caused by a parasite called Giardia. They live in the intestine region of living creatures and can cause stool. In the worst cases, they can cause diarrhoea for even weeks and months. Diarrhoea, dehydration, stomach pain, gas and foul-smelling excretions are some of its symptoms.

Conclusion

These parasitic microorganisms depend on various living creatures like humans and animals to survive. Apart from other similar parasites, protozoa have a unique feature as it is capable of altering their shape and relocating from one place to another place. In this article, we have learnt about protozoa, types of protozoa, and examples of protozoans.