NOT all creatures huddle together for protection when under stress. Blast common soil bacteria with sunlight and they move away from each other as fast as they can.
Arshad Kudrolli, a physicist at Clark University in Worcester, Massachusetts, and his colleagues were studying how Bacillus subtilis responds to damaging ultraviolet light. They bathed a Petri dish of the bacteria in UV light, except for a circle of shade which they moved slowly around the dish.
As expected, bacteria in the shaded patch followed it around. But oddly, all the other bacteria fled to the edge of the Petri dish, even though the UV was just as strong there. Tests showed that the stressed-out bugs had become sensitive to their own waste products, and spread out in a ring as they tried to escape the collective output.
B. subtilis can be found in places such as the Antarctic. Here, the thinned-out ...
To continue reading this article, subscribe to receive access to all of newscientist.com, including 20 years of archive content.