Sticky trails of sugar and protein secreted by slime moulds help the single-celled organisms to find their way, by marking where they have previously travelled.
Christopher Reid at the University of Sydney in Australia and his team found that the slime mould Physarum polycephalum (pictured) — which senses and migrates towards chemical cues such as glucose — avoids its own secretions if possible, preferring to seek food in unexplored areas. When researchers used a U-shaped barrier to trap the creature en route to a glucose snack, 96% of organisms found their way out within 120 hours, mostly by trying untested territory. However, when the entire environment was coated in slime, only 33% of slime moulds reached the goal in that time, and those that did travelled longer distances than organisms in a slime-free setting.
Slime moulds use their trails to navigate complex environments more efficiently, the team concludes.
Proc. Natl Acad. Sci. USA http://dx.doi.org/10.1073/pnas.1215037109 (2012)