Alexandra has taught middle school science and has a master's degree in Math and Science Education.
What Is a Protist?
Have you ever seen a green slime growing on the sides of a fish tank or swimming pool? Just because it's green doesn't mean it's a plant! That green slime is called algae, and it is special kind of living thing called a protist. Protists are very simple organisms made of one cell and are usually very tiny, and they don't fit into the category of animal, plant, fungus or bacteria.
Protist Features and Habitat
Protists come in all different shapes. Some are oval and covered in tiny hairs. Some have long, thin tails. Others may even look like a splat of slime! Some protists eat food (decaying matter they come across), while others create their own food through photosynthesis.
What's so cool about protists is they can have characteristics of both plants and animals. This is why they have their own special classification. They are so odd that scientists didn't know what to do with them!
One thing that most protists have in common is that they live near or in water, including ponds, rivers, oceans and even puddles. This helps them move with ease--they often have tiny hairs and thin tails that act like mini paddles to help them swim. It's just like having flippers on your hands and feet in the swimming pool!
Examples of Protists
There are hundreds of thousands of different species of protists and many more yet to be discovered. Some of these protists are bad guys--they can make people and animals sick, feeding off of their hosts and even causing diseases such as malaria.
But most protists are harmless and even essential to the environments where they live. Let's talk about two common and important protists.
Algae is a type of protist that is often mistaken for a plant. It can make its own food using the process of photosynthesis, which means it uses sunlight, oxygen and water to create sugar. Beyond that, algae does not share any common structures with a plant.
Algae can grow together in large groups called colonies, which makes it seem like one large plant. Imagine a giant snowball. While a snowball can get pretty big, when you look close, you see that it's really made of small, individual snowflakes. In the same way, an algae colony is made up of many algae.
An amoeba looks like a splat of slime! It holds no shape and moves by stretching out in one part of the cell called a pseudopod (which means 'false feet'). It can also use its pseudopod to surround something it wants to eat and pull the food inside the cell to digest. If we acted like ameobas, we would use our hands to drag our bodies around all day and shovel in food!
Protists are very small single-celled organisms that do not fit into any other classification--they're not animal, plant, fungus or bacteria. Most protists live in or near water to help them move around easily. While most protists are harmless, like algae and amoeba, some can make people sick.
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