Structure: They typically have an elongated cell with one nucleus. They are surrounded by a pellicle, a flexible, proteinaceous layer just inside the cell membrane that allows them to change shape (a movement called metaboly). 

Locomotion: Usually possess one or two flagella for movement. 

Photosynthesis: Many species contain chloroplasts with the pigments chlorophyll a and chlorophyll b, allowing them to perform photosynthesis 

Reproduction: Reproduction is typically asexual by longitudinal cell division. 

Food Storage: The carbohydrate product of assimilation is stored as a specialized polymer of glucose called paramylon, which is unique to this group.

Eyespot: A red-pigmented eyespot (stigma) is present, which is thought to be light-sensitive and helps the organism move toward light. 

Nutrition: They are considered mixotrophic, meaning they can also feed heterotrophically 

Example: Euglena

Movement & Feeding: They move and capture food using temporary, finger-like extensions of their cytoplasm called pseudopods 

No Permanent Shape: They are typically naked (no shell or cell wall) and constantly change their body form. 

Nutrition (Heterotrophs): They are animal-like, feeding by surrounding and engulfing their prey (phagocytosis)

Cytoplasm: Their cell material (cytoplasm) is divided into a clear, stiff outer layer (ectoplasm) and a more granular inner layer (endoplasm). 

Freshwater Balance: Freshwater species have a contractile vacuole 

Examples : Amoeba, Entamoeba, Foraminifera

Locomotion & Feeding: They move and gather food using hundreds or thousands of short, hair-like structures called cilia 

Complex Cell: They have a defined, permanent shape and a specialized feeding groove called an oral groove or cytostome 

Unique Nuclei: They have two types of nuclei (large macronucleus and one or more small micronuclei)

Contractile Vacuole: Like many freshwater protists, they have a contractile vacuole to expel excess water. 

Nutrition: They are heterotrophs (animal-like) and feed on bacteria, algae, and smaller protists. 

Examples: Paramecium, Stentor, Vorticella

All Parasites: Every organism in this group is an obligate parasite. 

No Motor Parts: In their adult stages, they lack cilia, flagella, or pseudopods for movement (gliding)

Complex Life Cycle: They have complicated life cycles that often involve multiple stages and sometimes two different hosts (like a mosquito and a human). 

Spore-Forming: They typically form spores (oocysts or cysts) as a resistant stage for transmission. 

Examples: Plasmodium, Toxoplasma Eimeria and Isospora