Protozoa are single celled organisms. They come in many different shapes and sizes ranging from an Amoeba which can change its shape to Paramecium with its fixed shape and complex structure. They live in a wide variety of moist habitats including fresh water, marine environments and the soil.
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.
Protozoa (also protozoan, plural protozoans) is an informal term for a group of single-celled eukaryotes, either free-living or parasitic, which feed on organic matter such as other microorganisms or organic tissues and debris. Some examples of protozoa are Amoeba, Paramecium, Euglena and Trypanosoma.
In many ways, protozoa and algae are similar. In biological terms, they belong to the same kingdom. They are both composed of eukaryotic cells, which means that they have a membrane-bound nucleus and some other basic cellular structures.
Protozoal disease
- Protozoan.
- Infectious disease.
- Malaria.
- Avian malaria.
- Leishmaniasis.
- Trypanosomiasis.
- Ich.
- Toxoplasmosis.
Protozoa have been classified into three trophic categories: the photoautotrophs which harness the sun's radiant energy in the process of photosynthesis; the photoheterotrophs, which although phototrophic in energy requirements, are unable to use carbon dioxide for cell synthesis and must have organic carbon compounds;
Characteristics of Protozoa
| Classification | Characteristic |
|---|
| Ciliophora (Ciliates) | Motile; covered with many, short cilia. |
| Sarcomastigophora (Flagellates) | Motile; have one or more long flagella. |
| Apicomplexa (Sporozoa) | Adult form is non-motile; many are parasites, and some can form spores. |
in 1990. According to this system, the tree of life consists of three domains: Archaea, Bacteria, and Eukarya. The first two are all prokaryotic microorganisms, or mostly single-celled organisms whose cells have no nucleus.
Prokaryotes are divided into two domains because studies on the organisms determined that there are enough differences to place them into their own
Algae have two mobile hairs that are called flagella, not cilia. Although mistaken for cilia, the flagella move in a much different way from cilia.
Plants, Animals, Protists, Fungi, Archaebacteria, Eubacteria. How are organism placed into their kingdoms?
Many bacteria have a multicellular phase of their lifecycle, which fall into three broad categories based on shape and mechanism of formation. A number of pressures may have selected for multicellularity, including physicochemical stress, nutrient scarcity, predation, and environmental variability.
The algae have chlorophyll and can manufacture their own food through the process of photosynthesis. Recently they are classified in the kingdom of protiste, which comprise a variety of unicellular and some simple multinuclear and multicellular eukaryotic organisms that have cells with a membrane-bound nucleus.
The common characteristics of Archaebacteria known to date are these: (1) the presence of characteristic tRNAs and ribosomal RNAs; (2) the absence of peptidoglycan cell walls, with in many cases, replacement by a largely proteinaceous coat; (3) the occurrence of ether linked lipids built from phytanyl chains and (4) in
All algae contain a pigment called chlorophyll a (other types of chlorophyll such as b, c and/or d may also be present) and they make their own food by photosynthesis. The chlorophyll is contained in the chloroplasts and gives many algae their green appearance.
Moss are a part of the kingdom plantae, which is located in the eukaryotic domain. So, they are not considered bacteria, fungi, or protists. Bacteria are in the prokaryotic domain, which is completely different.
Thallophyta is a division of the plant kingdom including primitive forms of plant life showing a simple plant body. Including unicellular to large algae, fungi, lichens. They are simple plants without roots stems or leaves. They are non-embryophyta.
Plants and other producers such as algae use these nutrients, which include carbon, nitrogen and minerals. Organisms that act as decomposers include fungi, bacteria and other microbes. Scavengers eat dead animals and are also considered consumers.
Algae are aquatic, plant-like organisms. They encompass a variety of simple structures, from single-celled phytoplankton floating in the water, to large seaweeds (macroalgae) attached to the ocean floor 2. Algae can be found residing in oceans, lakes, rivers, ponds and even in snow, anywhere on Earth.
Algae are photosynthetic creatures. They are neither plant, animal or fungi. Many algae are single celled, however some species are multicellular. Many, but not all of red and brown algae are multicellular.
Remains of colonial blue-green algae have been found in rocks dating back more than 4 billion years. As a whole, these types of fossils represent nearly 7/8th of the history of life on this planet! However, they are considered bacteria, not plants.
Macroalgae are classified into three major groups: brown algae (Phaeophyceae), green algae (Chlorophyta), and red algae (Rhodophyta). As all of the groups contain chlorophyll granules, their characteristic colors are derived from other pigments. Many of the brown algae are referred to simply as kelp.
The main reason is that they contain chloroplasts and produce food through photosynthesis. However, they lack many other structures of true plants. For example, algae do not have roots, stems, or leaves. Some algae also differ from plants in being motile.
Algae can also produce chemical defenses to protect themselves from predators. The green algae Halimeda have high concentrations of defense chemicals to prevent herbivores from eating it. Both processes help algae survive in different environments.
The term "algae" (singular: alga) is used to denote a vast array of plant-like organisms. Modern genetic studies have shown conclusively that the organisms called algae belong to several different kingdoms and are mostly not plants at all. Lichens are a mutualism formed between fungi and various groups of algae.
The protozoan cell carries out all of the processes—including feeding, growth, reproduction, excretion, and movement—necessary to sustain and propagate life. The cell is enclosed in a membrane called the plasma membrane.
The very main reason for calling protozoans are acellular and not as unicellular because, all protozonas are made of a single cell and all those will live in groups and so, while calling group of protozoans, we should mentyion as acellular organism and not as unicellular organism.
Protozoans consist primarily of eukaryotic and single-celled organisms. They are represented by four major groups namely Flagellates, Ciliates, Sarcodina, and Sporozoans.
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.
Protists are unicellular eukaryotes that are not plants, animals, or fungi. Algae and protozoa are examples of protists. Protozoa (singular: protozoan) are protists that make up the backbone of many food webs by providing nutrients for other organisms. Protozoa are very diverse.
Protozoa are notable for their ability to move independently, a characteristic found in the majority of species. They usually lack the capability for photosynthesis, although the genus Euglena is renowned for motility as well as photosynthesis (and is therefore considered both an alga and a protozoan).
The protozoa that are infectious to humans can be classified into four groups based on their mode of movement:
- Sarcodina – the ameba, e.g., Entamoeba.
- Mastigophora – the flagellates, e.g., Giardia, Leishmania.
- Ciliophora – the ciliates, e.g., Balantidium.
Protozoa species move on their own by one of the three types of locomotor organelles such as flagella, cilia, or pseudopodia. Protozoa reproduce by the method of binary fission or multiple fission. Some of the members reproduce by asexual mode, some by sexual means, and some by both.
