Describe the classes of protozoa.

1.Mastigophora
1. Move by means of flagella
2. They also use flagella to capture food and as sensory receptors
3. The body has a definite shape / form and is covered with pellicle
4. Some contain chlorophyll and are categorized as plants (phytomastigophora – plank like) – zoomastigaphora - animal like)
5. Some inhibit soil, others are aquatic – both fresh and salty waters and serve as food for small aquatic animals
6. Cause vital diseases in animals
E.g. Genus Trypanosoma – a blood parasite / pathogen in vertebrates
Uses invertebrates (insects) as intermediate hosts
e.g. Trypanosoma brucei – occurs in antelopes and other game animals in Africa.
Causes Trypanosomiasis / Nagana in cattle
The parasite is transmitted by Tsetse flies belonging to genus Glossina spp.
2. Leishmania sp. – causes Leishmaniasis or also kala-aza.
Attacks endothelial cells in blood vessels of man.
Example of phytomastigophora (Euglena)
Contains chlorophyll and can photosynthesize

2.Sarcodina (Amoeba)
1. Move about by flow of protoplasmic extrusions known as pseudopodia (false feet)
2. They lack cell wall
3. Their body shape changes during movement
4. Most amoebas are free living and not infectious
5. Entamoeba histolytica is a parasite of humans and causes amoebic dysentery (affects ileum and colon)
6. Reproduce asexually by binary fission (nucleus divides cell constricts at the middle and splits to 2 daughter cells)
7. Are uninucleate and encyst under unfavorable conditions

3.Ciliophora (ciliates)
1. Body is covered by numerous short hair like structures called cilia which provide locomotion
2. Most have 2 nuclei, macronuclei and micronuclei.
3. The majority of ciliates are free living and harmless
4. Most have definite mouth and feeding organelle
5. Most develop cysts to survive unfavorable conditions
Representative genus - paramecium
6. Important genera causing disease.
Balantidium coli – zoonotic in pigs, causes balantidiosis

4.Apicomplexa (sporozoa)
1. The entire group is parasitic
2. Lack locomotory structures, motility is absent except in male gametes
3. Food is absorbed directly from the host through saprozoic nutrition
4. Life cycles are complex with well-developed asexual and sexual cycles
(Asexual reproduction is by multiple – asexual fission – schizogony) – Cell becomes multi-nucleate by repeated mitosis and the cytoplasm divides into many uninucleate cells.
Sexual reproduction is by micro and micro gametes which join in pairs to form zygotes called oocysts (thick walled)
5. Produce special spore like cells called sporozoites following sexual reproduction which are important in transmissions of infections.
Representative genus - Plasmodium – causes 100-300 million cases of malaria each year worldwide. An intracellular parasite of blood cells and tissues.
- Transmitted by female anopheles mosquito
- Asexual cycle takes place in man and sexual phase takes place in the mosquito.
Species P.Vivax P.Falciparum P.ovale P.malariae
- Toxoplasma gondii – causes acute infection (toxoplasmosis) in humans acquired from cats
And other animals /pets
- Cryptosporidium – an intestinal pathogen transmitted by contaminated water

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Kavungya answered the question on March 12, 2019 at 14:02