Introduction

1 Hochner B. Octopuses. 2 Packard A. Cephalopods and fish: the limits of convergence. 3 Fiorito G.

Scotto P. Observational-Learning in Octopus-Vulgaris. 4 Gutnick T.

Byrne R.A.

Hochner B.

Kuba M. Octopus vulgaris uses visual information to determine the location of its arm. 5 Huffard C.L.

Boneka F.

Full R.J. Underwater bipedal locomotion by octopuses in disguise. 6 Finn J.K.

Tregenza T.

Norman M.D. Defensive tool use in a coconut-carrying octopus. 7 Norman M.D.

Finn J.

Tregenza T. Dynamic mimicry in an Indo-Malayan octopus. Cephalopods are unique amongst invertebrates, their extremely large nervous system containing as many neurons as in the dog brain (around half a billion []). They are intelligent, visually active hunters and compete successfully with vertebrates for the same ecological niche []. In the laboratory they readily learn to associate a visual or tactile stimulus with a negative or positive reward, they can learn by observation [] and can decide into which compartment of a three-arm maze to push the tip of their arms []. Studies in natural habitats have shown the amazing abilities of these animals to disguise themselves, imitate poisonous species and to use tools [].

Perhaps most astonishing is that they do all this with a soft, boneless body and with eight long, flexible arms. How have the muscular, neuronal and sensory systems of the octopus adapted to this unusual body plan to support its advanced behavior? Recent neurophysiological and behavioral studies on the species Octopus vulgaris have revealed an organization of the nervous system/body interactions that helps answer this question. In this review, I argue that the sophistication of the cephalopods' behavior emerges from its special embodied intelligence.

8 Pfeifer R.

Lungarella M.

Iida F. Self-organization, embodiment, and biologically inspired robotics. 9 Brooks R.A. New approaches to robotics. The embodied intelligence concept (see []), although not a direct outcome of biological studies, is definitely inspired by biological systems, which are amazingly efficient in generating adaptive behaviors with ease and elegance. The approach was developed for designing autonomous robots, which, unlike industrial robots, such as those used in car assembly, are highly adaptive to their environment. The first class of robots using this approach ‘behave’ without sensory input or feedback in a kind of an open-loop or feed-forward controlled system. The second class needs to process a tremendous amount of internal and external physical and sensory information to generate its adaptive autonomous behavior. Roboticists find it important to design such robots as a whole, with what they consequently refer to as an embodied organization.

8 Pfeifer R.

Lungarella M.

Iida F. Self-organization, embodiment, and biologically inspired robotics. Figure 1 Schema describing the embodied organization of behavior. Show full caption 8 Pfeifer R.

Lungarella M.

Iida F. Self-organization, embodiment, and biologically inspired robotics. Behavior emerges from the interaction of the agent and the environment through a continuous and dynamic interplay of physical and information processes rather than from a hierarchical organization. (Reproduced with permission from Pfeifer et al..) The term ‘embodiment’ implies the dynamic interplay of information and physical processes between four components comprising the embodied creature: the controller, the mechanical system, the sensory system and the task-environment (see Figure 1 , reproduced from Pfeiffer et al. [], where additional information can be found). While in open-loop robotic systems behavior arises from more hierarchical top-down control, in an embodied organization the behavior arises from the system as a whole through dynamic physical and information interactions among all its components. These reciprocal, dynamical interconnections ensure that the system functions optimally in its ecological niche when each component is adapted (by evolution or self-organization) to the embodiment functionality; this ensures best adaptation in the bottom-up direction, where the morphology and the properties of the material are adapted for interaction with the ecological niche. Proper adjustment of the interactions between the morphology, the mechanical system and the environment achieves physical stability and energy efficiency; simplifying motor control as it leaves it to deal mainly with perturbations.

10 Mainzer K. From embodied mind to embodied robotics: Humanities and system theoretical aspects. 11 Chiel H.J.

Ting L.H.

Ekeberg O.

Hartmann M.J.Z. The brain in its body: motor control and sensing in a biomechanical context. The materials and the physical interaction with the environment shape the pattern of the physical and sensory feedback. From the point of view of information processing such constrained interactions create statistical regularities in the sensory and motor information. That is, through its behavior, the robot structures its own sensory inputs (information self-structuring; Figure 1 ), reducing their dimensionalities and simplifying and speeding up information processing. In a robot, these dynamic interactions, together with the plastic processes at different levels, especially at the level of the controller [], may lead via self-organizational processes to the emergence of an efficient adaptive behavior in a specific environment ( Figure 1 ). This embodied intelligence approach has proved efficient for solving complex robotic problems. It does not seem unreasonable that biological evolution has followed similar principles [].

The unusual morphology of the octopus and its highly adaptive behavior is an excellent case in which to explore whether similar embodied organization principles play a constraining role in the evolution and self-organization of biological systems. Here, I review neurophysiological and behavioral findings from studies of motor control in the octopus as an inspiration for robotics, as well as relevant findings on the neural bases of learning and memory in octopus and cuttlefish. I argue that the embodied organization approach indeed provides an interesting framework for understanding many of the unique features of the octopus nervous and muscular systems. Embodied organization thus appears a valid approach for further understanding the functioning of complex dynamical biological systems. I believe that it is a universal constraint in the evolution of adaptive behavior in animals, both simple and complex.