Protozoans

Definition

Protozoans are single-celled eukaryotic organisms often classified by their movement mechanisms. They can be free-living or parasitic and are found in various aquatic environments.

5 Must Know Facts For Your Next Test

1. Protozoans are categorized into groups such as amoeboids, flagellates, ciliates, and sporozoans based on their locomotion.
2. Many protozoans cause diseases in humans, such as malaria (caused by Plasmodium spp.) and amoebiasis (caused by Entamoeba histolytica).
3. They reproduce primarily through asexual methods like binary fission but can also undergo sexual reproduction.
4. Protozoans have complex life cycles that may involve multiple hosts and stages of development.
5. They possess specialized organelles like contractile vacuoles for osmoregulation and food vacuoles for digestion.

Review Questions

• What are the main methods of locomotion used to classify protozoans?
• Name two human diseases caused by parasitic protozoans.
• How do protozoans typically reproduce?

Related terms

Amoeboids: Protozoans that move using pseudopodia or 'false feet'.

Flagellates: Protozoans that use one or more whip-like flagella for movement.

Ciliates: Protozoans that move using hair-like structures called cilia.