Characteristics of Kingdom Protista

• Eukaryotic and unicellular (2-200µ in size).
• Colonial or simple multicellular forms.
• Do not develop from a blastula or embryo.

Diversity Among Protista

• Evolution led to diversity in size, structure, locomotion, nutrient acquisition, interactions, habitat, and reproduction.

Major Groups of Protista

1. Animal-like Protoctista (Protozoa)
2. Plant-like Protoctista (Algae)
3. Fungi-like Protoctista (Primitive fungi)

Animal-like Protoctista (Protozoa) Characteristics

• Microscopic, primitive creatures; solitary or colonial.
• Nutrition types: holozoic, holophytic, saprozoic, parasitic.
• Intracellular digestion and respiration via diffusion.
• Asexual and sexual reproduction methods.

Classifications of Protozoa

• 30,000 species classified into:

1. Class Sarcodina (Amoebae)
2. Class Flagellata (Zooflagellata)
3. Class Ciliata
4. Class Foraminiferans
5. Class Actinopoda
6. Class Apicomplexa

Class Sarcodina (Amoebae) Traits

• Uninucleated with cytoplasmic extensions (pseudopodia).
• Asexual reproduction by fission; mostly free-living with some parasitic forms (e.g., Entamoeba histolytica).

Class Flagellata Traits

• Unicellular, with one to many flagella for movement.
• Reproduce mainly asexually, some symbiotic; examples include Trichonympha and Trypanosoma.

Class Ciliata Traits

• Covered with cilia for movement; have contractile vacuoles.
• Exhibit two types of nuclei (macronucleus and micronucleus) and feature conjugation.
• Examples: Paramecium, Vorticella.

Class Foraminiferans and Actinopoda

• Marine organisms that produce shells (tests).
• Foraminifera tests made of calcium; Actinopoda tests made of silica.

Class Apicomplexa

• Parasitic protozoans causing diseases like malaria (e.g., Plasmodium).
• Asexual and sexual reproduction; complex life cycles with hosts.

Symptoms of Major Protozoan Diseases

• Entamoeba histolytica: Dysentery.
• Trypanosoma: Sleeping sickness.
• Leishmania: Kala-azar.
• Giardia: Diarrhea.
• Plasmodium: Malaria symptoms include fever, chills, and fatigue.

Comparison of Protozoan Classes