A protist is any eukaryotic organism that is not an animal, plant or fungus. They don’t form a natural group, or clade, but are often grouped together for convenience. Scientists also do this with other groups such as algae or invertebrates. Protists can be either photosynthetic or heterotrophic. There are also two different kinds of heterotrophic protists, they are phagotrophs and osmotrophs. The difference between all of these types of protists is how they gain their nutrients. Protists are also able to reproduce through binary fission or multiple fission.
The picture below is of a simple eukaryotic protist called Euglena. It is a diagram that shows the different organelles that are in most eukaryotic protists.
“EUGLENA” By fickleandfreckled under Flickr
Protists are the cause of multiple diseases that infect humans. Some of these diseases include malaria, sleeping sickness, amoebic dysentery and trichomoniasis. Malaria is caused by five species of the parasite Plasmodium, and humans contract the disease if they are bitten by female Anopheles mosquitoes. The most common parasite is the Plasmodium falciparum, this one is also the deadliest for humans.
“Plasmodium” by Jfbranch14 under Creative Commons Attribution-Share Alike 3.0 Unported
“Plasmodium falciparum” by CDC/Dr. Mae Melvin under Centers for Disease Control and Prevention
The two pictures above show two types of the Plasmodium parasite. The diagram on the left shows the basic structure and organelles of a plasmodium parasite and the picture on the left show an image taken through a microscope of the Plasmodium falciparum parasite. This is the parasite that is most commonly found in humans with malaria and it is also the deadliest.
Protists also have huge effects on the environment. Algae account for almost 50% of all photosynthesis that takes place. This is very important for the environment. photosynthesis is so important for all of the life on earth. Without it, most organisms would disappear, and over time it would change Earth’s atmosphere. Protists are also able to control bacteria populations by feeding on them. This is very important because if the bacteria population got out of control then that could effect other species and populations and eventually the whole ecosystem could be affected.
“Algae” by Publicdomain.net under CC0 Public Domain
This picture above shows lots of algae on a lake. All of this algae is taking part in photosynthesis. If you are more interested in algae and what it does to and for the environment then you can check out one of my other posts on the red tide with is caused by algal blooms.
There is one very interesting protist that was discovered in 2012, it was named Collodictyon. It was discovered in lake Oslo in Norway. What makes this particular protist so interesting is that it is unlike any other one ever discovered. Scientists weren’t even sure what group to place it into, but it seemed that it was closest to protists. Some scientists believed that it belonged to a new Kingdom on the Tree of Life. Though it is eukaryotic, when scientists were able to analyze its genome they found that it doesn’t quite fit in as an animal, plant, fungi, algae or protist. They believe that it evolved around a billion years ago and it is one of the oldest known living eukaryotes. Its closest known living relative is the protist Diphylleia, so it has remained in the same group as a protist since its discovery. I think that this new species is a very interesting example of the tree of life growing and changing as we discover new species. In the future scientists may discover other protists similar to this one and maybe they will form a new Kingdom, or it could just be an outlier and remain as a protist.
Here are two images of the Collodictyon.
“collodictyon” by Daily Mail
“Collodictyon” by CC0under