So in this video, one of the main takeaways is really just to reinforce this idea that protists are incredibly diverse in terms of both their structure and their function. In fact, protists are so diverse that there's actually no single characteristic that's unique only to all protists. Or in other words, there's no single characteristic that's found in every single protist that is unique to the protist group and is not found in organisms outside of the protist group. Now you might be thinking, wait a second, aren't all protists eukaryotes? Well, yes.
All protists are eukaryotes, but being eukaryotic is not a feature that's unique to the protist group since animals like you and I, plants, and fungi are examples of eukaryotes that are not protists. Now this being said, there are still some generalizations that we can make that apply to most protists. And so most protists tend to have the standard eukaryotic organelles that we've talked about in previous lesson videos, which you can see over here on the left-hand side of the image. But some protists may have some unique organelles, like some of these unique organelles that we show you here on the right-hand side of the image, including pellicles, which are a strip of proteins that surrounds the cells of some protists just underneath the cell membrane that provides rigidity to the structure of the cells that contain them. Contractile vacuoles, which absorb water and, upon contracting, can eject water outside of the cell to prevent the cell from lysing in hypotonic environments.
And some protists have a structure known as an ocelloid, which is an eye-like structure that allows these protists to visually detect their surroundings, which is pretty remarkable to think about. Now the vast majority of protists are actually unicellular in nature. However, there are some multicellular protists. For example, kelp is an example of a multicellular protist. And most protists actually tend to live in wet, moist soils and or in aquatic ecosystems.
In fact, in most cases, protists are going to be the most abundant organism in aquatic ecosystems, and protists can play very important ecological roles, and they're also important medically as well since they can cause diseases in humans such as malaria, for example. Now, protists are also very diverse in terms of the way that they acquire their nutrients. So protists can either be heterotrophic, photosynthetic, or they can be what's called mixotrophic, which as its name implies with the root mix there is really just a combination of the two, a combination of heterotrophic and photosynthetic. And so this here concludes our lesson on the diversity of protist structure and function, and moving forward, we'll be able to learn more about protists and apply these concepts in problems. So I'll see you all in our next video.
