Scientists Say: Amoeba

This word describes a shape-shifting microbe made up of a single cell

a microscopic image of two amoebas

These amoebas have long, skinny “false feet” called pseudopodia that stretch ahead of them, pulling them along.

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Amoeba (noun, “Uh-MEE-buh”)

This word describes a single-celled microbe that moves by shape-shifting. To pull themselves along, amoebas extend temporary bulges from their cells. These are called pseudopodia (SOO-doh-POH-dee-uh). That word means “false feet.”

Some amoebas lack any structure. They look like blobs. Others shape up by building a shell. They may use molecules they make themselves. Others can build shells with materials gathered from their environment.

Amoebas eat using their pseudopodia. They can eat bacteria, algae or fungal cells. Some even eat small worms. Amoebas engulf a bit of prey by surrounding it with their pseudopodia. This encloses the prey inside a new unit within the amoeba’s cell, where it gets digested.

Amoebas may seem similar to bacteria. Both are groups of single-celled microbes. But amoebas have a key difference. They are eukaryotes (Yoo-KAIR-ee-oats). That means their DNA is contained in a structure called a nucleus (NEW-clee-us). Bacterial cells lack these structures.

Some amoebas live freely in damp places. Others are parasites. That means they live off of other organisms. Amoebas that are parasites in humans can cause disease. For example, the amoeba Entamoeba histolytica can infect the human gut. This microbe eats cells of the intestine and can cause severe illness or death. Amoebas are very common in some areas of the world. But generally, these microbes cause fewer illnesses each year than viruses or bacteria.

In a sentence

An amoeba called Naegleria fowleri causes disease in people by eating brain cells.

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Carolyn Wilke is a former staff writer at Science News Explores. She has a Ph.D. in environmental engineering. Carolyn enjoys writing about chemistry, microbes and the environment. She also loves playing with her cat.

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