Saturday, April 11, 2009

Lifting the edge of the blanket

I spent some time yesterday fishing the blanket weed out of my smallest pond, and took the opportunity to take a look at the microscopic organisms that live in it. There were vast numbers of ciliate protozoans, about a twentieth of a millimetres long, whizzing around at a tremendous speed. They are propelled by fringes of microscopic hairs that beat in rhythm and they can change direction instantly, so they can be tricky to photograph. The ciliate in the picture here might be a species of Oxytricha, but I’m not totally sure about that. The green objects inside it are algae that it has ingested. The two videos show a large rotifer that was attached to the blanket weed, with its ‘wheel organs’ (rings of rhythmically beating cilia) creating a vortex that sucks food into its constantly chewing jaws. These animals always remind me of twin-head electric razors. Blanket weed can be a pain in ponds, but it supports a vast array of minute organisms that are the base of a food chain for larger animals.


  1. Great clear picture and video. Are those tiny objects whizzing around in the first video also ciliate?
    From time to time I get problems with blanket weed but at the moment it is confined to one corner of the pond. As you say it supports an important part of the food chain.

  2. Fantastic rotifer video. What a marvellously engineered microbe. Twin-head razor, definitely, and perhaps a floor polishing machine too.

  3. Thanks for the comments. Yes, the minute objects in the background are very small ciliates. Sometimes they get sucked into the rotifer's vortex.

  4. The ciliate is an oxytrichid, but not Oxytricha. It is a Tetmemena, probably T. pustulata (better known under its old name, Stylonychia pustulata).

    1. Thanks Bruce - I really appreciate your help in getting the correct IDs.


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