Mr. Carl's e-Class Topic:  Protists

What is a Protist?

All protists are eukaryotic.  That is, all protists have cells with nuclei.  In addition, all protists live in moist environments.

Protists can be unicellular or multicellular.  Protists can be microscopic or can be over 100 meters (300 feet) long.  Some protists are heterotrophs, while others are autotrophs.

Since protists vary so much, we will group them into three subcategories: animal-like protists, fungus-like protists, and plant-like protists.

Animal-like Protists

Animal-like protists are divided into four basic groups based on how they move and live.
 

Protists with Pseudopods	Protists with Cilia	Protists with Flagella	Others
These protists move by extending their bodies forward and then pulling the rest of their bodies forward as well (check it out).  The finger-like structures that they project forward are called pseudopods.  The pseudopods are also used to trap food.	These protists move by beating tiny hair-like structures called cilia.  The cilia act as tiny oars that allows the protist to move through its watery environment (check it out).  The cilia also help the protists capture food.	These protists move by beating their long whiplike structures called flagella.  These protists can have one or more flagella that help them move.  Many of these protists live in the bodies of other organisms.  Sometimes, they help their host, while at other times they harm their host.	These protists are chartacterized mainly by the way they live.  All of these protists are parasites.  Many of these protists cause diseases such as malaria.
The ameba is an example of this type of animal-like protist.	The paramecium is an example of this type of animal-like protist.	The Giardia is an example of this type of animal-like protist.	The Plasmodium is an example of this type of animal-like protist.
			Image
Ameba Anatomy	Paramecium Anatomy	Giardia Anatomy and Live Cycle	Life Cycle of Plasmodium

Fungus-like Protists

Water Molds	Downy Mildews	Slime Molds
Live in water or moist environments Look like tiny threads with a fuzzy covering Attack food such as potatoes, cabbage, and corn and can destroy whole crops		Live in moist soil and on decaying plants and trees Very colorful Move by forming pseudopods Feed on bacteria and other microorganisms.

Plant-like Protists

These plant-like protists can be unicellular, multicellular, or live in colonies.  The plant-like protists are divided into four basic groups:  euglenoids, dinoflagellates, diatoms, and algae.
 
 

Euglenoids	Dinoflagellates	Diatoms
Autotrophs when sunny Heterotrophs when dark Unicellular Found mostly in fresh water Some have flagellum	Unicellular Covered by stiff plates Have two flagella May glow in the dark Found in ocean	Unicellular Glasslike cell walls Used in toothpastes, scouring products, and as filters
Euglenoid Anatomy	Dinoflagellate Anatomy	Diatom Anatomy
Algae
Green Algae	Red Algae	Brown Algae
Are green in color Mostly unicellular, but some form colonies, and a few are multicellular Live in fresh water, salt water, and a few live on land	Multicellular Commonly called sea weed Live in deep salt water Are used by humans to help make ice cream and hair conditioner Are eaten in some Asian cultures	Multicellular Commonly called sea weed Have large leaf-like structures called blades Have air-filled sacs called air bladders Have root-like structure called holdfast Live in salt water Are used by humans to help make pudding and salad dressing