Understanding Protozoans and Locomotory Structures
Protozoans are single-celled eukaryotic organisms that exhibit a variety of forms and locomotory structures. The presence or absence of these structures can define their classification and functional characteristics.

Protozoans and Their Locomotory Structures
- Protozoans often move using various structures such as flagella, cilia, or pseudopodia.
- For example:
- **Entamoeba**: Uses pseudopodia for movement.
- **Trypanosoma**: Moves with a whip-like flagellum.
- **Paramecium**: Uses cilia to navigate through water.

Plasmodium - The Non-Motile Protozoan
- **Plasmodium** is the correct answer as it is a protozoan that lacks any locomotory structures.
- It is the causative agent of malaria and is transmitted by female Anopheles mosquitoes.

Characteristics of Plasmodium
- **Life Cycle**: Plasmodium has a complex life cycle that includes both asexual and sexual stages, primarily occurring in the human host and the mosquito vector.
- **Motility**: Unlike other protozoans, Plasmodium does not have the ability to move independently; it relies on the host's blood circulation for distribution and transmission.

Conclusion
In summary, Plasmodium distinguishes itself from other protozoans like Entamoeba, Trypanosoma, and Paramecium by its lack of any locomotory structures, making it a unique and significant organism within the study of protozoan biology and disease pathology.