Flatworms Recall Familiar Environs, Even after Losing Their Heads

The flatworms known as planarians are neuroscience darlings. Their centralized brain, complex sensory abilities and rapid regenerative capacities make these nonparasitic worms ideal for studying the mechanisms that regulate stem cell function, neuronal development and limb regrowth.

http://www.scientificamerican.com/article.cfm?id=flatworms-recall-familiar-environs-even-after-losing-their-heads