Protozoa- these are microscopic creatures which may be fifty times larger than bacteria, but still cannot be seen without a microscope. Important disease caused by these organisms are malaria and amebic dysentery.
They are unicellular (single-cell), complex, animal-like microorganisms. They are characterized by an irregular or fluctuant shape without a cell wall, and many are motile. Protozoa can be divided into four categories: amebas, ciliates, flagellates, and sporozoa.
