Characteristics of Protists
Protists are unicellular organisms which belong to eukaryotic cells, yet they are simpler than a number of eukaryotes. Protistsconsist of very organized structures in their cells, which are called organelles.These organelles perform a number of complex functions.
Generally, protists are unicellular,yet there are some multicellular protistsas well that mostly belong to algae (brown and red algae) in the kingdom of protists.
Types of Protists
A large number of organisms are there in the Protista kingdom. Protists have many types as per their structure, function and survival. Moreover, there is another way of categorizing the protists, based on their movement. There are three main types of protists according to the way of their movement. These types are flagellates, ciliates, and rhizopoda.
- Flagellates:There is a tail at the back of the cell body in such types of protists. They can move forward with the help of their tail.
- Ciliates:There isspecial microscopic hair on the cell body in such types of protists. They can propel themselves forward in liquids when they flap their hair together in a series.
- Rhizopoda: These types of protists use their body to propel themselves. They make pseudopodium (false feet) by letting their body to flow in a direction where they want to move.
How Protists Survive?
Different types of protists survive differently from one another. They gather energy for themselves in different ways, such asphotosynthesis, digesting food, and eating pre-digested food and the like. Protists thatsurvive on photosynthesisare called algae. These are not plants as certain structures are absent in their bodies.
Major Groups of Protists
Protista has 3 main groups:algae, slime moulds and protozoa.Each of these groups has its own characteristics and functions. These are as follows:
Algae (These perform photosynthesis)
Algae are closer to plants because they can perform photosynthesis. But they differ from plants due to the lack of some structuressuch as roots, leaves and stems. Algae have a variety of colours likered,green and brown.
Slime Moulds (These are similar to fungus)
Slime moulds have some characteristics similar to fungi. These are generally found in compost and rotten wood. They depend on decaying matter for their survival and spread slowly for searching food.
The cells of slime moulds come closer to form a dense groupwhen the food scarcity increases. Acellular slime moulds may fuse together to form a single cell when they form a dense group. This cell contains a large number of nuclei. While cellular slime moulds do not form a single cell by merging together. They stay as individual cells in a dense group.
Protozoa (These are similar to animals)
Protozoa have some characteristics that are somewhat similar to animal cells. Protozoa can move freely and cannot produce food for themselves. They can move by pseudopodia, cilia or flagella. In addition, some protozoa seize to move on reaching adulthood.
Amoeba is an example of protozoa, which is a single cell organism. It is capable of moving with pseudopodia (false feet) and taking external sources of food. Amoebadoesnot follow a single shape and changes its shape all the time.
- Many types of protists can make a person sick, and are categorized in pathogens.
- When an amoebais cut in two halves,it doesnot die. If it is done, the half of amoeba having a nucleus will be alive, but the other half having no nucleus will die.
- Malaria disease is generally spread by mosquitoes when they bite us. It is caused by a protist, called Plasmodium falciparum.
- There are some protistswhich are edible, for example, red algae.
- The kingdom of Protista was not accepted into the scientific community until 1967, although it was created in 1866.