Vorticella Recoil

For speedy reactions this takes some beating. Vorticella is a beautiful bell-shaped ciliate that may be found moving freely but is often anchored by a thin line to vegetation. The movement of the cilia round the bell opening produces a powerful stream in the surrounding water.

If threatened, maybe by collision with a large creature, the vorticella retracts the anchor line in a small fraction of a second and then extends over a period of a few seconds before starting up the cilia again. The action of the cilia beating helps keep the line taught.

The MPEG1 video clip that you can download from this link is 11 seconds long and 1.8M bytes in size. There are 301 frames, so we're talking about 30 frames a second. Between frames 64 and 65 the retraction has occurred!

The part I particularly like is when the cilia start again and you can see the bell head move sharply to the right and the neighbours get a bit stirred up.

For those who don't wish to download the video clip here are some stills.

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