What are the protozoa?

Protozoa are unicellular eukaryotes, free-living microorganisms that come in a range of shapes and sizes. Protozoa measure between 10 and 100 micrometers. Protozoa live in most environments including fresh water, soil, and marine environments. They thrive in damp, moist and extreme conditions and can multiply and produce spores in these extreme conditions. There are more than 65,000 species of protozoa which use ‘pseudopodia (cytoplasmic extensions) to engulf their food. They search and eat other microbes to survive and have the ability to multiply in human hosts which enables them to survive, and can cause serious infections from just a single organism.

Protozoa must have a water supply, mineral elements and oxygen to reproduce which can be done sexually or asexually. The most common type of protozoa reproduction is done asexually when cell division takes place. There are two types of cell division which are binary fission (where two cells are formed), and Multiple fission (where many cells are formed).

There are four types of protozoa: Ciliates, Apicomplexan, Flagellates, and Amoebae. Ciliates have small hair-like structures that cover the outer layer of the microbe. Ciliates feed on bacteria and algae by sweeping it into the mouth via their oral cilia. Cilia can be distinguished into three types – crawling, stalked and free swimming. Cilia beat in a regular continuous pattern like flexible oars.