Amoebas are single-celled organisms in the Kingdom Protista. They are characterized by their shape-changing movement as the protoplasm pushes the cell membrane out into what are called "false feet" or pseudopods. Some amoebas have many pseudopods, while others, such as the one pictured here and in the video, have one primary pseudopod.


The protoplasm contains a large assortment of cell organelles and other material. The only easily recognizable organelles in the videos are water or contractile vacuoles. These vacuoles or sacs fill up with water and other materials, which are periodically expelled from the cell (you can see them "disappear" in the videos). The vacuoles function to (a) maintain a water balance in the cell, (b) eliminate waste products, (c) isolate and eliminate potentially dangerous substances, and (d) regulate the pressure inside the cell.

In terms of metapatterns, the amoeba tends to be a flattened sphere or sheet. It's sheet-like form:

  • maximizes its contact with the environment as an increased surface area to volume ratio, which allows for the absorption of water; and
  • provides for the two-dimensional movement of the protoplasm.

Inside of the amoeba are various organelles, many of which are spherical, such as the nucleus and water vacuoles. These spherical bodies act as containers for specific types of materials. In addition, it's cell membrane acts as a border with pores that:

  • regulate the absorption of water and other materials; and
  • regulate the elimination of water and waste materials (as is seen in the video as the use of water vacuoles).

The amoeba in these videos is most likely Trichamoeba osseosaccus. These amoebas have one primary pseudopod and a trailing bulge with filaments extending out from this area. In the labeled photo of this amoeba, the ectoplasm is a thicker, less fluid, and clear part of the protoplasm that appears along the leading edge of the pseudopod. It eats algae and tends to be found in bodies of freshwater with lots of vegetation.

This amoeba was a real find, since it is rarely found in nature.

©2010 Jeffrey W. Bloom


Add a New Comment
Unless otherwise stated, the content of this page is licensed under Creative Commons Attribution-ShareAlike 3.0 License