Ciliates
Paramecium
Paramecium (ciliate)
The slipper-shaped ciliate that almost every pond or hay-infusion slide turns up sooner or later.
What to look for
- Slipper or cigar shape, with an oral groove running diagonally to a mouth about halfway along.
- Even coat of cilia all over; the cell swims forward in a spiral, rotating as it goes.
- Two contractile vacuoles, one near each end, that fill into a star shape and empty in turn.
- When it bumps into something it backs off, turns a little and tries again (the avoiding reaction).
Size in the field
At 100× a large Paramecium takes about a sixth to a tenth of the field width; at 400× it crosses half the field.
Where to find it
Hay infusions, ditches with rotting leaves, the scum on still water.
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