Protozoan Phyla: Sarcomastigophora, Ciliophora, Apicomplexa

• Protozoans are unicellular animals
• Some protozoologists consider protozoans a separate kingdom named Protista
• Protozoans include plant-like forms and animal species that are free-living, commensal, mutualistic, and parasitic

Protozoan Phyla

• Sarcomastigophora
• Labyrinthomorpha
• Apicomplexa
• Microspora
• Acetospora
• Myxozoa
• Ciliophora
• The major phyla of protozoans, in terms of species composition, are Sarcomastigophora, Ciliophora, and Apicomplexa
• Phylum Sarcomastigophora is the most species-diverse, followed by Ciliophora and Apicomplexa
• Sarcomastigophora > Ciliophora > Apicomplexa based on species composition

Phylum Sarcomastigophora Characteristics

• Sarcomastigophorans possess flagella, pseudopodia, or both for locomotion and feeding
• Sarcomastigophorans have a single type of nucleus
• The phylum is sub-divided into three sub-phyla: Mastigophora, Sarcodina, and Opalinata

Subphylum Mastigophora Characteristics

• They have one or more flagella for locomotion
• Members exhibit autotrophic, heterotrophic, and saprozoic modes of nutrition
• There are two classes under this sub-phylum: Phytomastigophorea and Zoomastigophorea
• Phytomastigophorea have chloroplasts are usually found among members, so they are autotrophic, such as Euglena, Volvox and Chlamydomonas
• Zoomastigophorea lack chloroplasts, so members are either heterotrophic or saprozoic, such as Trypanosoma, Trichomonas, Giardia, and Leishmania

Subphylum Sarcodina Characteristics

• They use pseudopodia for movement and food gathering
• Members are naked or with shell or test
• They have two superclasses: Rhizopoda and Actinopoda
• Rhizopoda includes amoebae such as Amoeba, Entamoeba, Difflugia, and Arcella, with pseudopodia in forms such as lobopodia, filopodia, and reticulopodia
• Actinopoda includes foraminiferans, heliozoans, and radiolarians

Phylum Apicomplexa Characteristics

• Parasitic protozoans use an apical complex for penetrating host cells
• The phylum name is derived from its characteristic apical complex
• Cilia and flagella are lacking except in some reproductive stages
• Examples are Plasmodium, Isospora, Toxoplasma, Monocystis, and Sarcocystis

Phylum Ciliophora Characteristics

• Protozoans possess simple or compound cilia at some stage in their life history
• Ciliophora have two different types of nuclei: macronucleus and micronucleus
• Most species are free-living, although some are parasitic
• Examples are Paramecium and Vorticella