Natural history illustration: Marvellous micro-organisms 1: Amoeba October 17th 2014

Story posted: Friday, 17. October 2014 by Lizzie Harper

Scientific illustration can involve drawing all sorts of natural history speciemns, botanical, animal, and even microscopic.  In this series of three blogs I'll give a brief introduction to three common (and very cool) micro-organisms.  The first is the Amoeba.

Amoeba are free-living aquatic creatures, and can be seen in any drop of standing fresh water that you put under a compound microscope.  They also occur in salt-water, and as parasites within other animals (such as humans).  The largest is a little under 1mm in size. They are forever changing their shape by oozing outwards into pseudopods, and use these to engulf food by surrounding it with a water droplet, then taking it into thier bodies for digestion. These packets of food are called food vacuoles. This engulfing process is known as phagocytosis. For a video showing this process please click on the link: Ameoba eats two paramecium.

Lizzie Harper natural history scientific illustrator amoeba annotated

Obviously, amoeba aren't blue (interestingly though, some other micro-organisms called Stentors most decidely are blue).  I used the colour to clarify the features of the amoeba.

Although they're always changing shape, ameoba seem to have a contantly defined posterior end, which is known as its uroid.

The contractile vacuole is used to regulate the amount of water within the ameoba, and is near the uroid.

As with all cells, the nucleus is where the information and genetic material required to "run" the organism is sited; controlling reproduction, eating, and growth.

The pseudopodium are organelles which are used to "walk" over the substrate.  They are extended from the body and then cytoplasm flows into them, propelling the ameoba forward.

The body of the ameoba is filled with cytoplasm.  This varies from the clear plasmagel (which tends to be toward the edges of the pseudopods, right below the cell membrane) to the granulated endoplasm (further within the body).

They breathe by diffusing oxygen through their cell membranes, and reproduce asexually by simply dividing the cytoplasm and the nucleus through mitotic division in a process called binary fission.  This produces two identical daughter ameobae.

Although I love micro-organisms I am certainly no expert, so please get in touch if you spot any errors, I'd be more than happy to fix them.  Next week: the Paramecium! And for the third micro-organism, I'll be looking at the euglena.

I'm afraid I've had to turn off the "comments" button on my blogs due to spamming.  If you would like to give any comments or feedback, please do so on my Facebook page or Twitter account or email me at lizzieharper@tinyworld.co.uk.  Many many thanks; and apologies.

Category:  Zoology Terms and Anatomy   |   Comments:  0   |   Viewed:  1429

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