Basic Organisms

Some of the most basic organisms are smarter than we thought. Rather than moving about randomly, amoebas and plankton employ sophisticated [blank] to look for food and might travel in a way that optimizes their foraging. Biophysicists have [blank] tried to explain how creatures of all sizes search for food. However, single-celled organisms such as bacteria seem to move in no particular direction in their search. To investigate, Liang Li and Edward Cox at Princeton University studied the movements of amoebas (Dictyostelium) in a Petri dish, recording the paths travelled by 12 amoebas, including every turn and movement straight ahead, for 8 to 10 hours per amoeba. Immediately after an amoeba turned right, it was twice as [blank] to turn left as right again, and vice versa, they told a meeting of the American Physical Society meeting in Denver, Colorado, last week. "This suggests that the cells have a rudimentary memory of being able to remember the last direction [blank] had just turned in," says Robert Austin, a biophysicist at Princeton who was not involved in the study.