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Cephalopods have been utilised in neuroscience research for more than 100 years particularly because of their phenotypic plasticity, complex and centralised nervous system, tractability for studies of learning and cellular mechanisms of memory (e.g. long-term potentiation) and anatomical features facilitating physiological studies (e.g. squid giant axon and synapse). On 1 January 2013, research using any of the about 700 extant species of "live cephalopods" became regulated within the European Union by Directive 2010/63/EU on the "Protection of Animals used for Scientific Purposes", giving cephalopods the same EU legal protection as previously afforded only to vertebrates. The Directive has a number of implications, particularly for neuroscience research. These include: (1) projects will need justification, authorisation from local competent authorities, and be subject to review including a harm-benefit assessment and adherence to the 3Rs principles (Replacement, Refinement and Reduction). (2) To support project evaluation and compliance with the new EU law, guidelines specific to cephalopods will need to be developed, covering capture, transport, handling, housing, care, maintenance, health monitoring, humane anaesthesia, analgesia and euthanasia. (3) Objective criteria need to be developed to identify signs of pain, suffering, distress and lasting harm particularly in the context of their induction by an experimental procedure. Despite diversity of views existing on some of these topics, this paper reviews the above topics and describes the approaches being taken by the cephalopod research community (represented by the authorship) to produce "guidelines" and the potential contribution of neuroscience research to cephalopod welfare.

The engrailed gene is a transcription factor required in numerous species for major developmental steps (neurogenesis, limb development, boundary establishment), and its evolution is known to be closely related to the evolution of the metazoan body plan. Cephalopods exhibit numerous morphological peculiarities among molluscs, such as a direct development, a complex sensory and nervous system (eyes, brain, giant axons), a reduced shell, a funnel, and a brachial crown. We assessed a potential recruitment of engrailed in the development of these derived traits and examined the expression pattern of engrailed during the organogenesis of the cuttlefish Sepia officinalis, by immunostaining. Engrailed was detected at the margin of the prospective internal shell, which is consistent with studies on molluscs having an external shell and confirms a conserved role of engrailed in delimitating the molluscan shell compartment. Interestingly, unexpected patterns were early detected in the emerging arms, funnel and optic vesicles and latter in tentacles and eye lids. We also identified an engrailed cognate in the squid Loligo, which provides new evidence that engrailed in molluscs is not restricted to a ‘shell function’ and has been recruited in the mollusc lineage for the emergence of morphological novelties in cephalopods. [ABSTRACT FROM AUTHOR]