Protozoa: Characteristics and Habitats

Study Notes

Protozoa are microscopic organisms that can be either free-living or parasitic, with a single mass of protoplasm making up their bodies.
Despite their small size, protozoa are complex organisms that perform all the functions of life, which require coordination between multiple organs.

Protozoa are found in a wide range of environments, including:
- Fresh and saltwater
- Soil
- Moist areas
- Brackish water, hot springs, and even glacial ice
Many protozoa live as parasites on invertebrate or vertebrate animals, or on various plants.

Protozoa are divided into four main groups based on their mode of locomotion:
- Mastigophora (flagellates)
- Sarcodina (amoebae)
- Ciliophora (ciliates)
- Sporozoa (sporozoans)

Mastigophora are extremely small, possessing both plant-like and animal-like characteristics.
They are characterized by the presence of a flagellum, a whip-like structure used for movement.
- Unicellular, with a single flagellum emerging from the front of the body (e.g., Euglena)
- Flagellum can be double, with one flagellum wrapping around the body and into specific grooves (e.g., Dinoflagellates)
Examples of Mastigophora include:
- Leishmania, which causes Leishmaniasis in humans and other vertebrates
- Trypanosoma cruzi, which causes African sleeping sickness

Sarcodina are small, single-celled organisms that can change shape.
They consist of a protoplasmic mass with:
- An outer, transparent layer called ectoplasm
- An inner layer called endoplasm, which can transform into the other through a process called gel-sol-transformation
They can form temporary or permanent protrusions called pseudopodia, used for movement.
Examples of Sarcodina include:
- Entamoeba histolytica, which causes amoebic dysentery in humans
- Free-living Foraminiferans, which live in oceans and form calcium or silica skeletons, contributing to the formation of petroleum-rich sediments.

Protozoa are microscopic organisms that can be either free-living or parasitic, with a single mass of protoplasm making up their bodies.
Despite their small size, protozoa are complex organisms that perform all the functions of life, which require coordination between multiple organs.

Protozoa are found in a wide range of environments, including:
- Fresh and saltwater
- Soil
- Moist areas
- Brackish water, hot springs, and even glacial ice
Many protozoa live as parasites on invertebrate or vertebrate animals, or on various plants.

Protozoa are divided into four main groups based on their mode of locomotion:
- Mastigophora (flagellates)
- Sarcodina (amoebae)
- Ciliophora (ciliates)
- Sporozoa (sporozoans)

Mastigophora are extremely small, possessing both plant-like and animal-like characteristics.
They are characterized by the presence of a flagellum, a whip-like structure used for movement.
- Unicellular, with a single flagellum emerging from the front of the body (e.g., Euglena)
- Flagellum can be double, with one flagellum wrapping around the body and into specific grooves (e.g., Dinoflagellates)
Examples of Mastigophora include:
- Leishmania, which causes Leishmaniasis in humans and other vertebrates
- Trypanosoma cruzi, which causes African sleeping sickness

Sarcodina are small, single-celled organisms that can change shape.
They consist of a protoplasmic mass with:
- An outer, transparent layer called ectoplasm
- An inner layer called endoplasm, which can transform into the other through a process called gel-sol-transformation
They can form temporary or permanent protrusions called pseudopodia, used for movement.
Examples of Sarcodina include:
- Entamoeba histolytica, which causes amoebic dysentery in humans
- Free-living Foraminiferans, which live in oceans and form calcium or silica skeletons, contributing to the formation of petroleum-rich sediments.