The fastest contraction in the microworld


 by Wim van Egmond

  The pictures show Spirostomum ambiguus stretched (left) and contracted (right)

The genus Spirostomum contains some of the largest Ciliates. The species pictured on this page, Spirostomum ambiguum, can grow to to a size of more than 4 millimetres. It can therefore be seen without the help of a microscope. When observed swimming in a little jar of pond water it looks like a little worm. Only with the help of a microscope you can see that it is a ciliate. The cell of this unicellular is totally covered with hairlike 'cilia'. On the picture you can see the rows of cilia running like a spiral along the body.

One of the remarkable things of Spirostomum is the way it can contract. The organism can contract it's body to 1/4 of it's length in 6-8 millisec which is the fastest contraction known in any living cell. When observing the creature under the microscope it is easy to watch the contraction by gently touching the sample.

Like many large single celled organisms (giant amoebas, or Stentor: the trumpet animalcule) it has not one nucleus but many. The nucleii form a long strand, like a string of pearls, visible as the lighter structure in the right image.

Spirostomum, like many cilates, feeds on bacteria. They are swept into the mouth opening with a row of specialized fused cilia. The mouth opening is very small and can be found on the side of the body.

If you have done a nice observation through the microscope, or have made pictures or drawings of microscopic organisms why not make an article for the web! Micscape is made for and by enthusiasts. We will help you to present your work on the web. Please contact the editor below or me.

 Comments to the author Wim van Egmond are welcomed.

or visit Wim's HOMEPAGE

Wim van Egmond 1998


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Published in October 1998 Micscape Magazine.

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