Cephalopod Nervous System Organization
This is an advance summary of a forthcoming article in the Oxford Research Encyclopedia of Neuroscience. Please check back later for the full article.
Cephalopod molluscs have the largest invertebrate nervous systems and demonstrate a commensurate repertoire of behaviors, including a sophisticated and extremely rapid adaptive coloration system, extraordinary facility in problem solving, and dramatic visually guided predation capabilities. These complex behaviors have long fascinated humans, and have spurred over a century of research on cephalopod nervous systems.
Extant cephalopods are morphologically diverse and can be divided into the nautiloids, which retain an external shell; and the coleoids, which include octopus, squid, and cuttlefish. Despite their divergence ~400 mya, nautiloids and coleoids share some underlying organizational principles and anatomical features in their nervous systems, including central brain masses situated around the esophagus flanked by a pair of optic lobes. The soft-bodied coleoid cephalopods have, however, developed many striking innovations, such as chemosensory suckers that line the arms, dozens of sharply distinguished lobes within the central brain, and a pair of neuroendocrine organs called the optic gland. Recent developments in cephalopod biology, including the availability of the octopus genome, have led to new insights into cephalopod nervous system organization, including the striking finding that the functional convergence of the cephalopod nervous system with that of vertebrates is paralleled by convergence at the molecular level.