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iLabs: Well-Fed Amoebas

June 22, 2012

Here is a video shot with my cell phone, through an acrylic shield, of an amoeba on our EVOS microscope. I need to work on this approach as there is a fair bit of reflection from the acrylic shield. But still, there is some worthwhile footage of the amoeba moving around by stretching its pseudopods or false feet.  Some additional facts about pseudopods (also called pseudopodium and pseudopodia) can be found here.

Amoebas use pseudopods as a means of locomotion – the false leg extends forward and the rest of the amoeba is pulled along in that direction. The video shows one of the amoebas in our lab culture as it moves back and forth, extending “legs” from its body as it moves forward, then retracting those legs and moving in another direction. The cytoplasm within the cellular membrane that encloses the amoeba’s structures, can be seen moving forward or backward, in whatever direction the pseudopods take.The organelles within the cytoplasm are carried along as if on a current.

They also use them to capture food, a process called phagocytosis. The leg extends out and around an algae or bacterial cell until the leg totally encircles and engulfs the prey, pulling it within the cytoplasm for digestion. Here is an animation of that process.

One type of cell in our own bodies that use this tactic are a White Blood Cells, such as neutrophil. It finds bacteria that may be causing infection in the body and proceeds to surround and engulf them.

In addition to the video above, here’s a couple of nice shots of that same amoeba, after it morphed into some different shapes. In the video above, as well as the shots below, the amoeba is surrounded by a variety of plant debris, bacteria, and small ciliates. LOTS to eat.  The measurement line for comparison is 200 microns or 0.2 mm:

amoeba splitting into two large pseudopods

Here is that same amoeba, splitting into two large pseudopods. A scale in microns can be seen in the photo to give a frame of reference for size.

Amoeba with two large pseudopods looking like a "V"

Another shot of that amoeba after it moved away from the sediment material.

For a good summary of information on amoebas, their structures, life cycles, etc. here is a Wikipedia link on Amoebas.

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