The Digestive Tract Of Cephalopods At The Interface Between Physiology And Ecology

Aristotle in the Historia animalium, (Book IV) gives one of the earliest descriptions of the anatomy of the cephalopod digestive tract, comparing it to that of other molluscs. From dissections of cuttlefish several key features of the cephalopod digestive tract were described: the beak (“teeth”) and radula (“tongue”), the passage of the oesophagus through the brain en route to the crop and stomach. The stomach is described as having spiral convolutions like a trumpet snail shell suggesting that the structure described is actually the caecum. The gut then turns anteriorly so that the anal opening is near the funnel leading a modern author to comment that they “defaecate on their heads” (Leroi, 2014). In the intervening two millennia research on the cephalopod digestive tract has been sporadic with much of the current knowledge arising from a series of studies in the 1950s to the 1970s by A.M. Bidder, E. Boucaud -Camou, R. Boucher-Rodoni and K. Mangold which established the basic mechanisms of digestion and absorption (e.g., Bidder, 1950; Boucaud-Camou et al., 1976). The last 10 years has seen a resurgence of research on the digestive tract stimulated by interest cephalopods (particularly Octopus vulgaris and Sepia officinalis) as candidate species for aquaculture and the potential impact of climate change on cephalopod ecology. Additionally, the inclusion of cephalopods in the European Union legislation regulating scientific research has necessitated improved understanding of dietary requirements and metabolism as well as the development of methods to monitor digestive tract function to ensure optimal care and welfare in the laboratory. Prompted by this resurgence of interest in the cephalopod digestive tract and an international workshop on the topic held in November 2015 we have collected a series of papers reflecting the current state-of-the art. The seventeen papers in this book combine original research publications and reviews covering a diversity of topics that are grouped under four main themes reflecting key topics in the physiology and ecology of the cephalopod digestive tract; feeding strategies, early life stages and aquaculture, anatomy and digestive physiology, care and welfare. This book provides a timely synthesis of ongoing research into the cephalopod digestive tract which we hope will stimulate further studies into this relatively neglected aspect of cephalopod biology. References Aristotle. The History of Animals, Book IV. Translated by D’Arcy Wentworth Thompson. Bidder, A. (1950). The digestive mechanisms of the European squids Loligo vulgaris, Loligo forbesii, Alloteuthis media and Allotuethis subulata. Q. J. Microscop. Sci. 91, 1-43. Boucaud-Camou, E., Boucher, Rodoni, R., and Mangold, K (1976). Digestive absorption in Octopus vulgaris (Cephalopoda: Octopoda). J.Zool.179, 261-271. Leroi, A.M. (2014). The Lagoon-How Aristotle Invented Science. Bloomsbury Circus, London.