In the Animal Kingdom, different species can be classified according to their level of biological complexity. Thus, the simplest beings among invertebrates are protozoa. It is believed that in the first forms of life there were already this type of organisms.
It should be noted that the term protozoan comes from the Greek and literally means “first animals”.
Characteristics of protozoa
Most of these beings are unicellular and have a defined nucleus inside the cell . As a general criterion, they have movement and some of them are heterotrophic, that is, they feed on other living beings. In some cases they are autotrophs, that is, they manufacture their own food in the same way as plants. Protozoa
There are four different types: flagellates, ciliates, rhizopods and sporozoans. All of them are classified in the Protista Kingdom. All protist organisms are microscopic, without cell walls, live in moist environments, have high reproductive rates and need oxygen to survive. These characteristics make these beings become natural water purifiers and, at the same time, precursors of trophic chains.
The earliest protozoa are believed to have appeared near the sea coast. In this sense, the organisms that arose in this environment have evolved and become a fundamental part of the food chain of other living beings.
The role of protists in different fields
Most of these beings are harmless. Some of them are very useful, as some protozoa are used in geology to search for oil.
Protists are used worldwide in wastewater treatment as these organisms mineralize organic matter. Likewise, they are used as organic fertilizers, in the manufacture of biofuels, to produce cosmetics, to manufacture pharmaceuticals or to prepare algae biomass. They can also be cultivated using artificial floating substrates or to feed the fish.
These organisms are also used in different food industries
Despite their many uses, some protists produce diseases such as malaria or certain diseases that affect plants.
In summary, protists include protozoa and comprise more than 30,000 different species that inhabit every aquatic ecosystem on the planet.
