Teardrops of the swan

Last year, the most marvellous thing we saw in the pond-water microscopy practical was a ciliate, and this year the prize goes to that same clade. Ciliates don’t disappoint.

This is Lacrymaria olor, the “teardrop of the swan”. It’s a predator, like the Vorticella from last year, but rather than sitting rooted to the spot, Lacrymaria is an actively swimming hunter, with an enormously extendable proboscis that it uses to capture prey:

Lacrymaria is only about 100 µm long in its unextended state, so although it’s just about visible to the naked eye, it’s still very, very small. Consider that the systems controlling its proboscis, its burrowing, and its hunting behaviour, are all fitted into a single cell, without benefit of a brain, or even a nervous system. Ciliates are truly wondrous beasts.