Protozoa are a type of eukaryotic and unicellular microorganism. Originally protozoa were thought to be very similar to plant-like protists, but this classification changed when it was discovered that protozoa maintain animal-like characteristics such as movement.
Although protozoa possess animal-like characteristics, they are not animals. They are tiny microbes which are remarkably diverse. For example, protozoa are found in virtually all environments such as in peat bogs, deep sea vents and arid deserts.
There are four main subgroups of protozoa and these subgroup classifications are based on how these protozoa move:
- Ciliates – move using cilia
- Flagellates – move using flagella
- Amoeboids – move using false feet
- Sporozoans – have no structures for movement
Since protozoa are eukaryotic organisms, they contain vacuoles, a cell membrane and all the other cellular machinery found in the cells of plants, fungi, animals and other eukaryotes. For example, protozoa use their cell membrane and vacuoles for food absorption and digestion. Their cell membranes assist in the engulfing of food and their vacuoles can give off useable nitrogen during digestion. Generally, protozoa feed on other organic matter, bacteria, fungi and other protozoans in some cases.
Protozoa are not a huge concern when it comes to human illnesses because they are usually harmless. With this being said however, protozoa are the cause of malaria and dysentery. Malaria is a disease transmitted by mosquitoes, but these infected mosquitoes carry a microorganism from the genus Plasmodium, in which five specific species are infectious.
Protozoa are truly remarkable microorganisms. They are capable of reproducing by the process of fission, they can move in a variety of ways despite having no skeletal system and take in oxygen through their cell membrane. They are single-celled, tiny organisms and so are in no way complex like organisms with a brain. However, they are another type of interesting life form living among us.