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.

The last five years have been extremely challenging, but also very innovative for cephalopod science, and the outstanding tradition of biological contribution with cephalopod molluscs as key players in science and human activities and interests has continued. This Research Topic is one of several dedicated to cephalopod molluscs (e.g., Hanke and Osorio, 2018; Ponte et al., 2018) hosted by Frontiers over the last few years, not to mention other papers published separately. Highlighting of cephalopod science is important because it has much to offer not only the life science community, but also more broadly the public perception of science and its understanding and relationship with scientific endeavour and cephalopods as living organisms and part of our everyday life (at least for most of us). This contribution illustrates the key needs that need to be overcome by the cephalopod research community, i.e. rapid and effective mechanisms for exchange of knowledge and resources, sharing of laboratory protocols, videos, tissues, samples and data-sets, innovative approaches and initiatives in public engagement. The cuttlefish comic included is an excellent example of a type of media that can be used to expand scientific knowledge to the public and human relationship with live animals. There are strategic challenges in convincing globally distributed policy makers and funders of the relevance of cephalopods in scientific advances, and also in the regulatory aspects, since cephalopods are the only invertebrates whose use is regulated in Europe in a research context and this increases the need for integrated oversight and direction in terms of ethics and animal welfare (e.g., Jacquet et al., 2019a; 2019b; Ponte et al., 2019). This Research Topic also aligns with the interests of the cephalopod community in stimulating public interest in cephalopods extending to a broader audience that could include chefs and gourmets, and fishers and scientists aiming to develop sustainable food resources. “CephsInAction: Towards Future Challenges for Cephalopod Science” Research Topic includes 14 papers from about 40 authors representing ten different countries, thus overlapping with the original parties that contributed to the COST FA1301 that, together with CephRes, promoted and supported this editorial initiative.

Physiology of Molluscs: A Collection of Selected Reviews is an informative two-volume sent that brings together some of the most important recent and unique developments in molluscan physiology. Volume Two includes reviews on the neural mechanisms of learning, reproductive behavior, responses to environmental stress and hormones, and neurotransmitters. With the rapid development of cutting-edge proteomic, molecular biological, and cellular imaging techniques, our understanding of molluscan physiology, specifically in the areas of neurobiology, reproductive biology, and shell formation, has increased exponentially over the last several years. With contributions from some of the world's leading experts in the field of molluscan physiology, this valuable two-volume set fills this void and will serve as an important resource for researchers, professors, and students.

This issue of Veterinary Clinics: Exotic Animal Practice, guest edited by Dr. Marion R. Desmarchelier, focuses on Behavior. This is one of three issues each year selected by the series consulting editor, Dr. Jörg Mayer. Articles in this issue include, but are not limited to: Behavior modifications for the exotic pet practitioner, Psychopharmacology for the exotic pet practitioner, Ferret behavior medicine, Rabbit behavior medicine, Pot-bellied pig behavior medicine, Abnormal repetitive behaviors and self-mutilations in small mammals, Medical causes of feather damaging behavior, Avian behavior consultation for the exotic pet practitioner, Bird of Prey behavior for the avian practitioner, Clinical reptile behavior, Amphibian behavior for the exotic pet practitioner, Fish behavior for the exotic pet practitioner, Invertebrate behavior for the exotic pet practitioner, and Non-human primate clinical behavior