Amoeba in Action

If your kitchen is like most kitchens, you probably have cabinets for cups and pots and pans, along with drawers for silverware and cooking utensils.  You might also have a drawer you call the “junk drawer.”  The things in this drawer aren’t actually “junk.”  If they were, you’d throw them away.  Instead, things usually get put here because they just don’t fit anywhere else.

You might be surprised to learn that the system for classifying organisms has its own “junk drawer.”  It’s called the protist kingdom.  Its members, like the contents of your kitchen junk drawer, are important, but don’t fit nicely in one of the other kingdoms.

Broadly, protists can be classified as animal-like, plant-like, or fungus-like.  It is important to remember that being “animal-like” does not make a protist an animal.  Such and organism, like plant-like or fungus-like protists, are members of an entirely different group of living things.

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Amoeba are protists that walk using a method called a false foot, or pseudopodia. The amoeba extend a “false foot” and then pull the rest of their body along with them.

Animal-like protists are called protozoa. Like animals, protozoa can move on their own and are heterotrophic. Some protozoa eat by wrapping their bodies around their prey, creating a “food storage compartment.” Toxins are then produced which paralyze the prey, and food moved into the waiting protist.

Other protozoa have flagella, or tails, that assist in feeding. The flagella whip back and forth creating a current that brings food to the protist. Still other protozoa are parasites, and get nutrients from a host organism, harming the host in the process.

Animal-like protists can be classified, or placed into groups, based on how they move. Some move with the aid of a flagellum (that’s the singular form of flagella.) Others have many small tail-like structures called cilia which they move back and forth to get around. Still others have what is known as a “fake foot” or pseudopodia. These protozoa have a part of their cell stretch out, which pulls the rest of the organism along. The amoeba is a common example of this type of protozoan. Finally, some protozoa don’t move at all.

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