Living in a sensory world very different from our own, octopuses provide a challenge and inspiration for generations of researchers. The highly developed visual system is in several aspects comparable to that of vertebrates, but their boneless highly flexible body and arms are unique in the animal kingdom. Despite of several years of research many open questions remain. To better understand and decipher the behaviors and abilities of the octopus, we used a series of maze apparatuses that required the animals to rely on sensory information collected only from individual arms, to solve an operant learning task.

Using two variations of a single arm Y shaped maze, we investigated two different sensory modalities. First, we investigated the ability of octopuses to learn to turn their arm in a specific direction in an opaque Y shaped maze, while eliminating informative tactile, chemical and visual cues. Therefore, making consistent correct choices, by inserting an individual arm into the left or right of the maze, could only be made based on learning arm positional information. Five of six subjects were able to successfully complete this task in less then 90 trials. A second set of experiments, testing tactile discrimination learning, was conducted using a modification of the Y shaped maze apparatus, uniquely allowing us to test intact animals. Eight out of nine animals learned this task in 60 to 90 trials. All animals showed a characteristic multi-peaked learning curve. Our present work sheds new light on tasks the octopus can conduct using a single arm. This raises questions to what extend octopuses might be aware of the position of their highly flexible bodies.

Acknowledgements:

This study was supported by the European Commission under the 7th Framework Programme in the theme of the Future and Emerging Technologies (FET)
(OCTOPUS IP, FP7-ICT 2007.8.5, FET) [231608].