It’s nice to find out that – old and jaded as I am – biology can still delight me.
Earlier this week, I covered a first-year practical teaching microscopy skills to first-years, through the medium of pond water. As well as the usual desmids, rotifers, Daphnia and nematodes, one lucky student found a little clump of Vorticella (or some near relative, I’m not a protistologist!)
Their German name Glockentierchen (“little bell creatures”) delights me almost as much as they do:They’re actually quite common in freshwater, but this is the first time I’ve seen them in our pond samples. Each one is a single cell, attached to the substrate by a thin stalk, which can contract like a spring. Despite their cute bounciness, they’re voracious predators: the ‘head’ end has a cell-sized mouth (cytostome) surrounded by tiny beating hairs (cilia) which help funnel prey into the cell to be digested. The diagram below is of Stentor rather than Vorticella, but gives you the rough idea: Vorticella is one example of a very large group of single-celled organisms called ciliates, which include the slightly more well known Paramecium. Their cells are amazingly intricate, and have sub-cellular compartments (organelles) playing similar roles to those that multicellular organisms have entire organs for. That such complexity can exist in a drop of pond-water smaller than your fingernail is one of the things that makes biology truly awesome.
Genuinely my favourite practical over these 2 years! Fascinating what you can find – I rememebr finding this little beauty in mine (or a similar species of the genus cyclopodia) http://www.micrographia.com/specbiol/crustac/copepo/cope0100/cycnaup0.jpg
Cute. I like that practical too. It’s quite hit-and-miss, in that some years you get buggerall, other years you get gastrotrichs and tardigrades and copepods and some weird unidentifiable thing with a flagellum that went crunch when you put on a coverslip too hard. I should make a list of those who stick it out for the full 3 hours as this may be a better indicator of suitability for postgraduate study than anything else we do!