Current state of knowledge
Current state of knowledge
Cephalopod research, i.e. the study of octopuses, cuttlefishes, squids, and of the chambered Nautilus is improving all across Europe. It currently spans from bioengineering, and commercial aquaculture to molecular biology, physiology, evolutionary-developmental biology, animal cognition, neuroscience, and behaviour.
Cephalopod molluscs are cognate far beyond all other invertebrates. Their anatomy and physiology exhibit many similarities to the Vertebrata in terms of complexity. Possessing large brains, cephalopods have extremely flexible behaviour and highly developed attention and memory capacities resembling those of some vertebrates, including discrimination and generalization, social learning and spatial awareness. Indeed, they have been regarded as ‘honorary vertebrates’ due to some of their brain functions.
The challenges provided by the new Directive increased the attention to cephalopod welfare in the cephalopod community. Several organizations dedicated efforts to create a coherent common ground to indicate adequate, standardized procedures for treatment, care, and management of these animals. As a result, several contributions have been produced and ‘Guidelines’ are under development. Still, these guidelines need practical evaluation and extension.
Despite the long standing tradition of using cephalopods as ‘laboratory animals’, there has been very little research on the complex behavioural, neural, and hormonal control of physiological responses to stress in captivity, and experimental manipulation in cephalopods. Objective indicators that an animal could be experiencing pain, distress or other suffering are essential for welfare assessment. A number of cephalopod species have been successfully kept in both open seawater and recirculating water systems but there is a need to clarify optimal rearing conditions. These species tend to be coastal cephalopods, and include benthic octopods and sepioids, whereas pelagic cephalopod species and squids in particular, are very difficult to maintain in captivity. Typical distress behaviours include directional squirting, aggression, repeated self-cleaning, the sloughing of ‘ghost suckers’, food avoidance, inking, and autophagy. Measures to reduce this stress need to be investigated. Physiological parameters, like skin paling, altered respiration or inking, could be useful to detect incipient suffering before behavioural responses arise and thus allow prevention of further pain. Some of these signs have been reported following a potential stressful stimulus, e.g. bradycardia, but no study has evaluated these parameters in response to stress or pain.
Action activities will further characterize physiological and behavioural signs of potential suffering and develop non-invasive and/or automated techniques for their measurement as well as innovative approaches that integrate all influencing factors for a comprehensive assessment of cephalopod welfare.
Knowledge about the capacity of cephalopods to experience pain and the molecules mediating pain perception is scarce as well. Indeed, the mechanism of action of the most frequently used anaesthetics, ethanol, magnesium chloride and clove oil, and whether they truly cause unconsciousness is still unknown. Magnesium chloride has been recently reported to act as a muscle relaxing agent rather than an anaesthetic, and if confirmed would not be any longer acceptable for use. In addition, recent research revealed that different species react unpredictably to various anaesthetics and that ethanol may in fact cause adverse reactions. This Action will support interrogation of, among other issues, the anaesthetics currently used, and assess them to determine species-specific protocols that minimize ‘stress’ to the animals.
Culturing of cephalopods in captivity is not straightforward. Some progress has been made in recent years on the culturing of Sepia officinalis, but breeding of Octopus vulgaris and most other species is still a challenge, and it constantly requires a supply of wild individuals. Attempts to rear and culture some octopus species have been successful, but restricted to few regions of the world. Considering the elevated commercial interests for these species, especially Sepia officinalis and Octopus vulgaris it will be beneficial for aquaculture to gain further insights into cephalopods welfare and development of culturing and husbandry techniques.
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