Chapter 2: The sub kingdom of Protozoa
Introduction
All living organisms are categorized into 5 main kingdoms: Bacteria and Archaea, which are 
prokaryotes (lacking a nucleus and cellular organelles), and the eukaryotes, which include 
Plantae (plants), Fungi (fungi), and Animalia (animals).However, today other classification including 
the kingdom of Protista in which several groups of eukaryotic organisms (Protozoa : animals 
like protists, Algae: plants like Protists and Fungi : fungi like Protists) is proposed.In earlier biological classifications 
Protozoa and metazoans are classified under the kingdoms of Animalia where unicellular 
protozoa were considered as simple animals.