This paper first explores 3 philosophical bases for attitudes to invertebrates, Contractarian/Kantian, Utilitarian, and Rights-based, and what they lead us to conclude about how we use and care for these animals. We next discuss the problems of evaluating pain and suffering in invertebrates, pointing out that physiological responses to stress are widely similar across the animal kingdom and that most animals show behavioral responses to potentially painful stimuli. Since cephalopods are often used as a test group for consideration of pain, distress and proper conditions for captivity and handling, we evaluate their behavioral and cognitive capacities. Given these capacities, we then discuss practical issues: minimization of their pain and suffering during harvesting for food; ensuring that captive cephalopods are properly cared for, stimulated and allowed to live as full a life as possible; and, lastly, working for their conservation.

While clearly of molluscan ancestry, the coleoid cephalopods are emergent within the phylum for complexity of brain and behaviour. The brain does not just have centralization of the molluscan ganglia but also contains lobes with “higher order” functions such as storage of learned information, and centres have been compared with the vertebrate cerebellum and frontal lobe. The flexible muscular hydrostat movement system theoretically has unlimited degrees of freedom, and octopuses are models for “soft movement” robots. The decentralized nervous system, particularly in the arms of octopuses, results in decision making at many levels. Free of the molluscan shell and with evolutionary pressure from the bony fishes, coleoids have evolved a specialty in cognition and they may have a simple form of consciousness. Cephalopods also have a skin display system of unmatched complexity and excellence of camouflage, also used for communication with predators and conspecifics. A cephalopod is first and foremost a learning animal, using the display system for deception, having spatial memory, personalities, and motor play. They represent an alternative model to the vertebrates for the evolution of complex brains and high intelligence, which has as yet been only partly explored.

We systematically analyzed octopus body patterns, based on locations of chromatophore nerve projection, using a proposed new species in the Octopus vulgaris Cuvier, 1797 complex, Octopus insularis Leite and Haimovici, 2008. Although some taxonomic studies have used body patterns as characters to describe octopus species, a systematic analysis would provide detailed descriptions to assist reliable comparisons among species. This approach also links body patterns, behaviors, and underlying physiology of the chromatophore system. Body patterns were characterized by percent occurrence, areas of skin, and number of components in each. To verify the distribution of chromatic components, skin patterns, and colors among areas of the body, we ran a cluster analysis on occurrence of the components. We identified a total of 16 chromatic, 5 texture, 9 skin units, 6 colors, and 9 chronic body patterns. The cluster analysis showed twelve distinct skin areas of the components' distribution (expressive fields). Smaller f...

It is always difficult to even advance possible dimensions of consciousness, but Birch et al., 2020 have suggested four possible dimensions and this review discusses the first, perceptual richness, with relation to octopuses. They advance acuity, bandwidth, and categorization power as possible components. It is first necessary to realize that sensory richness does not automatically lead to perceptual richness and this capacity may not be accessed by consciousness. Octopuses do not discriminate light wavelength frequency (color) but rather its plane of polarization, a dimension that we do not understand. Their eyes are laterally placed on the head, leading to monocular vision and head movements that give a sequential rather than simultaneous view of items, possibly consciously planned. Details of control of the rich sensorimotor system of the arms, with 3/5 of the neurons of the nervous system, may normally not be accessed to the brain and thus to consciousness. The chromatophore-based skin appearance system is likely open loop, and not available to the octopus’ vision. Conversely, in a laboratory situation that is not ecologically valid for the octopus, learning about shapes and extents of visual figures was extensive and flexible, likely consciously planned. Similarly, octopuses’ local place in and navigation around space can be guided by light polarization plane and visual landmark location and is learned and monitored. The complex array of chemical cues delivered by water and on surfaces does not fit neatly into the components above and has barely been tested but might easily be described as perceptually rich. The octopus’ curiosity and drive to investigate and gain more information may mean that, apart from richness of any stimulus situation, they are consciously driven to seek out more information. This review suggests that cephalopods may not have a similar type of intelligence as the ‘higher’ vertebrates, they may not have similar dimensions or contents of consciousness, but that such a capacity is present nevertheless.

Birch et al. suggest that consciousness in any animal group must involve four aspects—perceptual richness, evaluative richness (affectivity), integration at one time (unity), and integration across time (temporality). This review will evaluate integration at one time in cephalopods, an area that offers many challenges. First, like most animals with a bilateral nervous system, cephalopods have laterality of brain function, and this challenges unity of function. Second, unlike most mammals, cephalopods have a heavy allocation of both neural and behavioural control to the periphery, especially in the case of octopuses. Third, like all animals, cephalopods gather information through several senses and there can be both unity within and competition between such information, challenging unity. Information gained across all these areas needs to be evaluated both in terms of the methodology used to gather information and the results of the investigation.