Amoebas - Shapeshifters of the microworld

Amoebas are free living eukaryotic organisms capable of changing their shape in order for it to move and feed. This is done by extending cellular projections called pseudopodia (see image). When the amoeba moves it uses these projections as a form of conveyor belt stretching towards the desired way of movement and the cell then fills the pseudopod with its insides called the endoplasm creating a sort of rolling movement as seen in the video below. When feeding, the organism will surround the food with its cell membrane and absorb it into its cell body where it is digested. A big part of the endoplasm is made up of these ingested particles as well as cellular organelles such as mitochondria and the nucleus containing the DNA.

One type of non-free living cell that looks, moves and feeds just like amoebas are our white blood cells. These tiny blobs crawl around with their amoeboid movement looking for intruders in our bodies which they can ingest to help in the never ending fight against infection. However as we all know, sometimes a pathogen will manifest itself before our immune system is able to kill it. And one of these pathogens could very well be an amoeba. One is called Entamoeba histolytica. This parasite causes symptoms like bloody diarrhea and abdominal pain when ingested. Another more sinister infection is caused by the brain eating amoeba Naegleria fowleri. Despite the name this is not a true amoeba but rather an amoeboflagellate. The organism is able to enter the brain when contaminated water comes into contact with the nasal cavity causing an often fatal brain infection.

Video showing freshwater amoebas and amoeboid movement at 5x speed. 

100x EC plan objective, brightfield illumination.