Protozoa can be seen in the drop of water. Sketches of the protozoa are drawn as observed under the microscope. They are identified by comparing their structures with those of different protozoa available in the literature (Figure 9.1).
Protozoan infections are responsible for diseases that affect many different types of organisms, including plants, animals, and some marine life. Many of the most prevalent and deadly human diseases are caused by a protozoan infection, including African Sleeping Sickness, amoebic dysentery, and malaria.
Protozoa vary in size and shape. Their sizes range from 10 to 55 micrometers, but they can be as large as 1 mm. The largest protozoa are called xenophyophores, which can measure up to 20 centimeters in diameter.
Protozoa play an important role in mineralizing nutrients, making them available for use by plants and other soil organisms. Protozoa (and nematodes) have a lower concentration of nitrogen in their cells than the bacteria they eat. Another role that protozoa play is in regulating bacteria populations.
For our purposes, there are only 4 groups of protozoa that will be covered here: these groups are separated by motility and cell structure.
- Amebas (representative: Ameba proteus)
- Flagellates (representative: Trypanosoma, Euglena)
- Ciliates (representative: Paramecium)
- Apicomplexa (representative: Plasmodium)
Protozoa (pro-toe-ZO-uh) are one-celled organisms, like bacteria. But they are bigger than bacteria and contain a nucleus and other cell structures, making them more like plant and animal cells. Protozoa love moisture.
11th Class Biology Kingdom Protista Protozoan Protists (Gr. Protos = first ; zoon = animal) It include all unicellular (or acellular) eukaryotic animals. These are most primitive organisms considered as animals because of heterotrophic nutrition and motility.
Protozoa are single-celled eukaryotes (organisms whose cells have nuclei) that commonly show characteristics usually associated with animals, most notably mobility and heterotrophy. They are often grouped in the kingdom Protista together with the plant-like algae and fungus-like water molds and slime molds.
Protozoa are unicellular eukaryotes. As in all eukaryotes, the nucleus is enclosed in a membrane. In protozoa other than ciliates, the nucleus is vesicular, with scattered chromatin giving a diffuse appearance to the nucleus, all nuclei in the individual organism appear alike.
Protozoa are unicellular eukaryotic microorganisms lacking a cell wall and belonging to the Kingdom Protista. Protozoa reproduce asexually by fission, schizogony, or budding. Some protozoa can also reproduce sexually. Relatively few protozoa cause disease.
Transmission of protozoa that live in a human's intestine to another human typically occurs through a fecal-oral route (for example, contaminated food or water or person-to-person contact).
Protozoology, the study of protozoans.
Most protist diseases in humans are caused by protozoa. Protozoa make humans sick when they become human parasites. Trypanosoma protozoa cause Chagas disease and sleeping sickness. Giardia protozoa cause giardiasis, and Plasmodium protozoa cause malaria.
Protists produce almost one-half of the oxygen on the planet through photosynthesis, decompose and recycle nutrients that humans need to live, and make up a huge part of the food chain. Humans use protists for many other reasons: Many protists are also commonly used in medical research.
There are three major types of fungus: mushrooms, molds and yeasts.
Most protists are aquatic organisms. They need a moist environment to survive. They are found mainly in damp soil, marshes, puddles, lakes, and the ocean. Some protists are free-living organisms.
Summary. Plant-like protists are called algae. They include single-celled diatoms and multicellular seaweed. Like plants, algae contain chlorophyll and make food by photosynthesis.
Animal-like protists include the flagellates, ciliates, and the sporozoans.
Kingdom Protista includes all eukaryotes that are not animals, plants, or fungi. Kingdom Protista is very diverse. It consists of both single-celled and multicellular organisms.
