Tuesday, June 16, 2009

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.

video video

7 comments:

  1. Just catching up on things Phil. What an unusual creature. It was great to see the videos of it 'in action'.

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  2. Hi John, It almost seems to be doing a sinuous sort of dance in one of the videos. Perhaps it should have a musical soundt track....

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  3. I don't think this is a lacrymaria, but one of the other swan-necked ciliates. It lacks Lacrymaria's distinctive oral structure (the "swan's head"), and I don't see the spiral ciliature. In the video and several of the pictures, a large cytostome is visible at the base of the "neck," where it would be located on a typical Dileptus. Indeed, the movement recorded in the video is more reminiscent of Dileptus than Lacrymaria.

    Excellent pictures, in any case.

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  4. You may well be right Bruce.....

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  5. I found your wonderful site (through psiwavelength's Skeptic Wonder blog) because I'm struggling to identify another swan-necked creature I posted on YouTube yesterday. Mine might be an Amphileptus procerus. For yours, consider Dileptus amphileptoides, as described here: http://protist.i.hosei.ac.jp/PDB/Images/ciliophora/dileptus/amphileptoides_2.html

    Your site went straight into my bookmarks. Thanks for doing it!

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  6. Thanks Bruce, this is really helpful - it does look very much like Dileptus. As you will have gathered, I'm a bit of a novice in protist-world! I'm going to get some more samples from the pond that this came from and have a closer look this time. Thanks for your ID and kind comments. All the best, Phil

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  7. Well, it's been a couple of years since I looked at these. I've been spending a lot of time with Dileptids, lately and this is clearly one (the mouth is very visible). What we see of the macronucleus points to the family Dimacrocaryonidae. It might be a species of Monomacrocaryon (e.g. M. polyvacuolatum)

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