From Science News:-
A dollop of living yellow ooze has aced a test of navigation, showing that you don’t really need a mind to make spatial memories.
The egg-yolk-colored slime mold Physarum polycephalum is a single cell without any nervous system. But this blob of a creature uses its slime trails as a form of external spatial memory, says complex systems biologist Chris R. Reid of the University of Sydney. Smears of goo left behind as a slime mold crawls act as records of past paths. Given a choice, slime molds won’t crawl over their old slime, Reid and his colleagues found.
These simple external “memories” work quite well. When lured into a U-shaped dead-end in front of a sugar treat, slime molds were able to escape. Instead of just throbbing futilely against the closed end of the U or crawling around in circles, 23 out of 24 managed to ooze their way back out of the blind alley and creep to the treat by an outside route, Reid and his colleagues report October 8 in the Proceedings of the National Academy of Sciences.
“It’s the first time any spatial memory system has been found in an organism without a brain,” Reid says.