Wednesday, March 18, 2015
Tears of a Swan
This strange little protozoan is called Lacrymaria olor, which means ‘tear of a swan’. When contracted it’s about a quarter of a millimetre long and tear-shaped. When it fully extends that long neck it’s about 2mm. long, which is gigantic as single-celled organisms go. The top photograph was taken using polarised light, which generates the attractive colours but the remaining photographs have been taken with interference contrast optics, which produce a less colourful result but more biological information. The next three photos down shows quite nicely why this organism is called ‘tear of a swan’ ......when it arches that long neck it looks - in outline – uncannily like a swan or perhaps, if you’ve a more fertile imagination, like the mythical Loch Ness monster. The final photo shows some structural detail of this remarkable protozoan, including some ingested food particles, contractile vacuoles that it uses to expel excess water and food waste and the lines of cilia that propel it through the water. If you double-click the photos you can see them a little larger. You may also be able to discern the cilia in the two videos, which show how active this organism is. You can read more about it at http://www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopy-uk.org.uk/mag/artapr00/rhlac2.html
Sometimes people wonder what motivates anyone to become a scientist. Despite being a practitioner since 1973 I was completely unaware that this amazing organism existed until about a month ago, when I read the Microscopy-UK web site article quoted above. Today was the first time I’d ever found one, in water around the roots of decaying reeds on the edge of a pond. That’s science for you – an unlimited source of new personal discoveries.
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