A role for nautilus in studies of the evolution of brain and behavior

Abstract

Nautilus is an ancient remnant of a largely extinct cephalopod lineage.¹ Its status within its clade is the subject of ongoing debate – its morphology, behavior and neuroanatomy may or may not be representative of an ancestral condition, and therefore its value as a model for ancestral cephalopods is uncertain. While the nautilus brain is simpler than that of more derived cephalopods² (coleoids), it is plausible that this is a secondary simplification related to ecology, and not a precursor to the vertebrate-like CNS of modern cephalopods. However, the absence of the vertical lobe complex, implicated in learning and memory in coleoids, makes studies of cognition in nautilus particularly interesting from a comparative perspective. Our research on the behavior and sensory biology of Nautilus pompilius gives the first indications of learning and memory in this ancient genus,³ and suggests that even with a far simpler brain containing no clearly defined ‘memory’ center, nautilus performs simple cognitive tasks comparably to its more derived relatives.

Acknowledgements

We thank Tina Kuroiwa and Chris Soucier for assistance with animal care, design of experimental apparatus and fruitful discussions of nautilus biology. We gratefully acknowledge the assistance that Roger Hanlon, Robert Rockwell, Peter Moller, Michael Kuba and Frank Grasso provided with design of our experimental procedures and constructive comments on our interpretations and results.

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