How Nervous Systems Evolve in Relation to Their Embodiment: What We Can Learn from Octopuses and Other Molluscs

Abstract

Cephalopods such as the octopus show the most advanced behavior among invertebrates, which they accomplish with an exceptionally flexible body plan. In this review I propose that the embodied organization approach, developed by roboticists to design efficient autonomous robots, is useful for understanding the evolution and development of the efficient adaptive interaction of animals with their environment, using the octopus as the leading example. The embodied organization approach explains adaptive behavior as emerging from the continuous dynamical and reciprocal physical and informational interactions between four elements: the controller, the mechanical and the sensory systems and the environment. In contrast to hierarchical organization, in embodied organization, self-organization processes can take part in the emergence of the adaptive properties. I first discuss how the embodiment concept explains covariation of body form, nervous system organization, and level of behavioral complexity using the Mollusca as an example. This is an ideal phylum to test such a qualitative correlation between body/brain/behavior, because they show the greatest variations of body plan within a single phylum. In some cases the covariation of nervous system and body structure seems to arise independently of close phylogenetic relationships. Next, I dwell on the octopus as an ideal model to test the embodiment concept within a single biological system. Here, the unusual body morphology of the octopus exposes the uniqueness of the four components comprising the octopus' embodiment. Considering together the results from behavioral, physiological, anatomical, and motor control research suggests that these four elements mutually influence each other. It is this mutual interactions and self-organization which have led to their unique evolution and development to create the unique and highly efficient octopus embodiment.

The Transition to Minimal Consciousness through the Evolution of Associative Learning

“…In cephalopod mollusks such as octopus and cuttlefish, two brain structures, the vertical lobe and the superior frontal lobe, form complex networks that are jointly analogous to the vertebrate hippocampus. These integrating brain structures serve as the basis for cephalopod learning and memory (Shomrat et al, 2011; Hochner, 2013). In gastropod mollusks the interactions between sensory integrating units, memory units for the storage of perception and action-patterns, and a flexible value system, do not seem to form similar multilevel processing.…”

Haematopoiesis in molluscs: A review of haemocyte development and function in gastropods, cephalopods and bivalves

“…Some are excellent model organisms for studying neurobiology [1, 2], while several others, such as clams, oysters, squids and abalones, are economically important food sources that can be reared in aquaculture [3–7]. Notably, gastropods are obligatory intermediate hosts for the vast majority of digenean trematodes, parasites that infect and cause disease in an incredible diversity of animals, including humans and livestock [8–10].…”

Embodied Organization of Octopus vulgaris Morphology, Vision, and Locomotion

“…Previous and more recent results suggest that the solution for this difficulty has evolved through “embodied evolution” of the octopus unique morphology to enable the nervous system to employ special motor-control strategies that alleviate the need to rely on central body parts representation (reviews: Zullo and Hochner, 2011; Hochner, 2012, 2013). …”