PROTOZOAnMultiple fission, numerous nuclear divisions precede rapid splitting of the cytoplasm into
many individuals.
nBudding, a portion of the parent breaks off and differentiates into a new complete
individual.
nEncystment, the individual loses its distinctive surface features such as cilia and flagella
and rounds off. Excess water is pumped out by the contractile vacuole and a protective
covering is secreted which hardens to form a protective cyst.
nColonial, a single individual divides to form a colony of attached genetically identical
individuals.
nFeeding and digestion
nDigestion is entirely intracellular — ingestion is by phagocytosis or endocytosis.
nFood particles become surrounded by external membrane forming a food vacuole which
moves about within the cytoplasm. The food vacuole is first acidic and then becomes
basic. Digestive enzymes are secreted into the vacuole.
nSoluble nutrients are absorbed into the endoplasm. Solid wastes are discharged through
an opening in the plasma membrane.Most of the parasitic protozoa of economic importance (parasites of man and domestic
animals) are found in the following phyla: the Sarcomastigophora and the Apicomplexa.
n 2.2 PARASITIC PROTOZOA OF ECONOMIC IMPORTANCE
Phylum Sarcomastigophora
nSubphylum Mastigophora
Class Zoomastigophora
Order Kinetoplastida: Leishmania; Trypanosoma
Order Dilpomomadida: Giardia
Order Trichomodida: Trichomonas; Histomonas
n Subphylum Sarcodina
Superclass Rhizopoda
Class Lobosea
Order Amoebida: Entamoeba; Acanthamoeba
Phylum Apicomplexa
n Class Sporozoea
Subclass Coccidia
Order Eucoccidida
Suborder Eimeriina: Eimeria; Isospora; Toxoplasma; Sarcoystis
Suborder Haemosporina: Plasmodium
Subclass Piroplasmia
Order Piroplasmida: Babesia; Theilerian 2. 3FLAGELLATED PROTOZOA
Flagellates (mastigophorans) have an outer pellicle, definite body shape and one or more
flagella (structure similar to cilia). Flagella often have mastigonemes (hair like projections)
along their length.