Protists or Protozoa Author: Paul D. The taxonomic kingdom Protista is a collection of single-celled organisms that do not fit into any other category. Protists are a group made up of protozoa, unicellular algae, and slime molds. Protozoa are the oldest known group of heterotrophic life that consume and transform complex food particles into energy. Although protozoans are only made up of a single cell, these organisms manage to perform all the basic tasks of life. The protozoa are divided into four major groups: the ciliates, the flagellates, the heliozoans, and the amoebas.
Ciliates:Ciliophora Structure in this group is fairly diverse, but almost all species retain a few basic characters that help to identify them as ciliates. The first character is the presence of cilia on at least one developmental stage of the organism. Modifications from the full body covered norm include a single ring of cilia, grouped ciliary organelles called cirri, and restriction of cilia to feeding tentacles.
Most species also bear toxicysts that are most likely used to capture and stun prey. These toxicysts can be found around the mouth, along the length of tentacles or anywhere else on the surface of the cell body.
Flagellates: Zoomastigophora Flagellates are characterized by having one or more flagella. Parasitic species generally have more flagella than those that are free living. Amoebas:Sarcodina Amoebas can reach a maximum size of 2 mm in diameter.
These protozoans are constantly changing shape; they look and move much like balloons half filled with water. When manipulating a water balloon you can force most of the water to one end or hold it so that different sections squeeze out between your fingers.
Amoebas change shape like that, only the forces are internal. They can create extensions of their body wall called pseudopodia that help them locomote or capture prey or simply churn up their insides to distribute nutrients.
The shape of a pseudopod is generally reflective of the family grouping to which it belongs. Algae produce toxic chemicals which are hazardous to humans. Protozoa are prokaryotic organisms, i. Protozoa are prokaryotic organisms belonging to the Protista kingdom. Protozoa are organisms possessing animal-like characteristics.
Protozoa are not capable of making their food. Hence they are heterotrophs. Algae are generally microscopic, which are unicellular. These types of unicellular Protozoa are called microalgae. In contrast, the types of multicellular protozoa are called macroalgae.
These grow at a length of hundred feet and are seaweeds. Kelp is an example of seaweeds. Algae make their food. They can swim by using flagella, which are whiplike strands, cilia or pseudopods, which are extensions of the cell that pull it along, or they do not move at all.
Amoebas are a type of protozoa that is very familiar. Some protozoans are responsible for human diseases, such as malaria. Algae and protozoans belong to the same kingdom, Protista, which is the kingdom that is used for many organisms that do not fit neatly into another category. Protists include algae, protozoa and slime molds. The major difference between algae and protozoa is that algae are able to make their own food, as plants do, while protozoa ingest other organisms or organic molecules, as animals do.
In scientific terms, algae are "autotrophs" and protozoa are "heterotrophs. Both protozoa and algae are eukaryotic organisms. Therefore, they consist of a membrane-bound nucleus. Both types can be unicellular. But, algae can also be multicellular. The main difference between protozoa and algae is that protozoa are heterotrophic , animal-like organisms whereas algae are autotrophic , plant-like organisms. This means protozoa ingest organic molecules by phagocytosis while algae produce their own food by photosynthesis.
Protozoa refer to single-celled animals that belong to the kingdom Protista. Though most protozoa are free-living, some of them infect higher animals.
Protozoa can obtain a variety of shapes due to the absence of a cell wall. The free-living vegetative form of protozoa is called the atropohozoite whereas the resting form is called a cyst. The cyst of the protozoa is analogous to the spore of bacteria.
Since protozoa are eukaryotic organisms, they contain a membrane-bound nucleus. Some protozoa may contain more than one micronuclei.
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