These single-celled protozoa, Stentor roeselii, are actually complex chemical computers (Image: Volker Steger / Christian Barpelle / SPL)
See also: Why microbes are smarter than you thought
A BAG of biochemistry less than a millimetre across that spends most of its life attached to pond scum, the single-celled organism Stentor roeselii doesn’t sound impressive. Yet its behaviour is remarkably sophisticated. Squirt a jet of water at a Stentor and it will dive into its mucus holdfast, emerging cautiously soon after. But squirt another identical jet at the same Stentor and it ignores it.
Now squirt a jet of an irritant…
