The Evolution of Flexible Behavioral Repertoires in Cephalopod Molluscs

Abstract

Cephalopods are a large and ancient group of marine animals with complex brains. Forms extant today are equipped with brains, sensors, and effectors that allow them not to just exist beside modern vertebrates as predators and prey; they compete fiercely with marine vertebrates at every scale from small crustaceans to sperm whales. We review the evolution of this group’s brains, learning ability and complex behavior. We outline evidence that although competition with vertebrates has left a deep impression on the brains and behavior of cephalopods, the original reorganization of their complex brains from their molluscan ancestors might have been forged in ancient seas millions of years before the advent of bony fishes.

Visual discrimination and object categorization in the cichlid Pseudotropheus sp.

“…The ability to visually discriminate between objects of different shapes and sizes has long been recognized within several vertebrate as well as invertebrate groups (Hoffmann and Logothetis 2009;Zoccolan et al 2009), including species such as monkeys (Nitsch and Jarosch 1972;Tanaka 2000), sea lions (Schustermann and Thomas 1966;Mauck and Dehnhardt 1997), chickens (Jones and Osorio 2003), bees (von Frisch 1914;Kaiser and Liske 1974;Srinivasan 2010) and octopus (Sutherland 1964;Grasso and Basil 2009).…”

Abstracts

“…Specifically, fast locomotory capabilities in coleoids coincide with the advent of efficient swimming styles in bony fishes [Chamberlain, 1993]. We posited that the foundations of coleoid brain complexity have earlier origins -from competition with diverse cephalopod groups and other marine forms before the advent of the bony fishes [Grasso and Basil, 2009]. Extant nautiloids have simpler brains than coleoids: 13 lobes versus ϳ 40 lobes [Young, 1971].…”

“…Brain expansion coincident with the coleoid radiation may be built upon an ancient architecture that predates the advent of bony fishes. Indeed, the learning and memory capabilities of nautiluses share marked similarities with the coleoids in capacity, duration and flexibility [Grasso and Basil, 2009]. In addition, the transition from a diffuse brain to an encephalized brain occurred 3-4 times in the evolution of molluscs, independent of the cephalopod lineage [Kocot et al, 2011].…”

Preface to Molluscan Neurobiology: Recent Advances and New Vistas

“…Even more remarkable is the convergence in the organization of the brain regions associated with learning Shomrat et al, 2008]. In this issue, Grasso and Basil [2009] summarize current thinking about the evolution of complex behaviors in cephalopods. They postulate that ecological pressure from fish pushed the cephalopods into two strategies: 'live fast, die young' (squid and octopus) and 'live slow, stay out of trouble' (nautilus).…”