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The common octopus (Octopus vulgaris) is an excellent candidate for aquaculture diversification, due to its biological traits and high market demand. To ensure a high-quality product while maintaining welfare in captive environments, it is crucial to develop non-invasive methods for testing health biomarkers. Proteins found in skin mucus offer a non-invasive approach to monitoring octopus welfare. This study compares the protein profiles in the skin mucus of wild, aquarium-maintained, and senescent specimens to identify welfare biomarkers. A tandem mass tag (TMT) coupled with an Orbitrap Eclipse Tribrid mass spectrometer was used to create a reference dataset from octopus skin mucus, identifying 1496 non-redundant protein groups. Although similar profiles were observed, differences in relative abundances led to the identification of potential biomarkers, including caspase-3-like, protocadherin 4, deleted in malignant brain tumors, thioredoxin, papilin, annexin, cofilin and mucin-4 proteins. Some of these proteins also revealed potential as bioactive peptides. This investigation provides the most extensive analysis of the skin mucus proteome in the common octopus and is the first to explore how aquarium maintenance and senescence alter the mucus proteome. This research highlights the potential of skin mucus protein/peptides as non-invasive monitoring biomarkers in cultured animals. [ABSTRACT FROM AUTHOR]

Over the past decade, there has been a growing interest in common octopus aquaculture, prompted by several factors such as the increase in market demand, the decline in overall fisheries and the search for more sustainable food resources. Nevertheless, this interest has raised concerns about the potential impact of largescale production and intensified farming practices in the future. This study aims to establish a baseline understanding of the natural microbial communities that inhabit skin mucus of the common octopus, describe its core microbiota, and assess the impact of captive rearing on these communities and animal welfare. The skin microbiome of wild-captured octopuses was compared with that of reared in aquaculture using 16S ribosomal RNA metabarcoding. The findings show that the core microbiota of octopus mucosal skin is dominated by the phyla Bacteroidota and Pseudomonadota, with Aurantivirga, Pseudofulvibacter, and Rubritalea being the most abundant genera. Despite differences in abundance, the microbiota composition and diversity between wild and aquaculture octopuses were similar. Wild samples had an enrichment of Gammaproteobacteria, including potentially pathogenic species such as Vibrio spp., Photobacteriumswingsii, and Lactococcus garvieae, which were less prevalent or absent in aquaculture samples. KEGG functional pathways predictions indicated a higher enrichment in functional pathways related to xenobiotic remediation in wild samples, reflecting their need to adapt to a more variable and potentially contaminated environment. This is the first study to characterize the mucosal skin microbiome of the common octopus and to compare wild and aquaculture specimens. The results suggest that current aquaculture practices support animal welfare through the use of controlled hatchery environments and high-quality water conditions. These insights are valuable for the development of sustainable and responsible aquaculture practices, with the octopus microbiome serving as a potential biomarker for health status and animal welfare. [ABSTRACT FROM AUTHOR]

Microbial communities play a crucial role in the physiology of animal hosts; however, little is known about bacterial symbionts with the group cephalopods, specifically octopuses, and the function of these symbionts. The goal of this study was to determine if octopuses have a unique skin microbiome. The skin microbiome of two sympatric octopuses (Octopus vulgaris and Macrotritopus defilippi) was compared with the surrounding environment, sediment and seawater, to determine if octopus have a unique skin microbiome. High throughput sequencing of the bacterial 16S rRNA gene (V3-V4 region) amplicons was performed using an Illumina MiSeq. Sediment showed the greatest alpha diversity followed by octopus then seawater. Beta diversity revealed a difference in microbial composition between the octopus skin microbiome and sediment and seawater. While phylum Bacteroidetes appeared rare in environmental samples, it was most abundant for the octopus skin microbiome with the majority of the bacteria comprising the family Flavobacteriaceae. Proteobacteria, the largest group of bacteria, also constituted the octopus skin microbiome. Many of these groups occur on both octopus species; however, certain taxa differed in relative abundance between octopus species and may show species-specific host selection. Several bacteria that were identified for the octopus skin microbiome have been isolated from other marine animal hosts, identified as biodegraders and/ or produce pigments and squalene, or act as predators of other bacteria. These groups may play a role in defense against environmental stressors or pathogenic bacteria. This is the first study to characterize the skin microbiome in two wild sympatric octopuses. Due to the importance of bacterial symbionts, this can provide insight to the physiology, behavior, ecology, and ultimately the health of these important animals in marine environments as well as care in captive or laboratory settings. [ABSTRACT FROM AUTHOR]

Octopus insularis is a shallow‐water octopus distributed throughout the western Atlantic, the Gulf of Mexico and the Caribbean. To evaluate its phylogeographic pattern, mitochondrial markers (16S rRNA and COIII) and genome‐wide nuclear markers (SNP's) were analyzed in individuals from artisanal fishing in different locations of the Colombian Caribbean coast. Mitochondrial analyzes displayed novel haplotypes (16S = H2, H3 and H4; COIII = H2–H7) and haplotypes shared with distant geographic areas (16S = H1 COIII = H1). The COIII gene did not show genetic differentiation between the analyzed localities, while the 16S gene showed significant differences between Santa Marta and Isla Fuerte. COIII's demographic analysis indicated that the species' effective population size has remained constant. Inferences were made from next‐generation genomic data with restriction site‐associated DNA (ddRAD‐seq) and 6769 polymorphic loci. The pairwise FST test indicated that there are low but significant differences between localities; however, the general molecular analysis of variance (AMOVA) and the principal coordinate analysis showed a lack of spatial structure in the populations analyzed. The Mantel test found no correlation between genetic distance and geographic distance, and the genetic structure analyses showed the presence of one genetic stock. The information obtained in this study indicates the genetic connectivity of O. insularis in the southwestern Caribbean, the absence of putative biogeographic barriers that affect its gene flow, and the crucial role played by life history strategies (planktonic paralarvae) and oceanographic factors to define the current distribution of its genetic diversity in this region. [ABSTRACT FROM AUTHOR]

This document is a postscript to a collection of papers that explore the effects of human actions on the welfare of invertebrates in various contexts. The papers discuss topics such as breeding facilities, research laboratories, and the wild. The document emphasizes the importance of considering the welfare of invertebrates, both in captivity and in the wild, and highlights the need for more research and information on this topic. It also addresses the ethical considerations and attitudes towards invertebrates, as well as the impact of human activities on wild invertebrates. The document concludes by emphasizing the significant influence humans have on the planet and the need to prioritize the welfare of invertebrates. [Extracted from the article]

Drying process was used in this study as a preserving method of octopus quality during storage. Octopus vulgaris quality attributes in terms of pH, water activity, color properties, total volatile basic nitrogen (TVB-N), trimethylamine (TMA), total viable count, and yeast and molds (YM) were evaluated. Samples were dried under sun drying and convective air drying and stored at ambient temperature. During storage, TVBN and TMA obtained were within the recommended level for good quality of dried samples. Accelerating shelf-life test was evaluated based on TVB-N, TMA, and YM, with shelf lives of 388 and 603 days for convective air drying and sun drying, respectively. [ABSTRACT FROM AUTHOR]

Octopuses are amongst the most fascinating animals in our oceans; however, while their intricate behaviours are often studied in laboratory settings, basic aspects of their movement ecology remain unstudied in the wild. Focusing on the socio-economically important common octopus (Octopus vulgaris), this study employs, for the first time, acoustic tracking techniques to address knowledge gaps regarding the species spatial ecology within a marine protected area. A total of 24 wild O. vulgaris (13 males, 11 females) were tagged in 2022 in the National Park Maritime-Terrestrial of the Atlantic Islands of Galicia, Spain. Acoustic transmitters were externally attached to the third arm, after testing other body parts (mantle cavity). Males were on average detected on 10 times more occasions than females (49 days in males and five in females). The average activity space in the study area was large in comparison to that determined in similar studies, with 0.16 km2. Activity space between males and females as well as day and night were comparable. Tagged octopuses displayed a crepuscular activity pattern. The location of dens could be established for 15 out of 24 individuals, from which octopuses were observed to undertake regular daytime excursions. Several individuals were also found to occupy more than one den and/or switch their main dens throughout the study duration. First implications and benefits of this approach are discussed. [ABSTRACT FROM AUTHOR]

This case study investigated the co‐occurrence of the curled octopus (Eledone cirrhosa) and common octopus (Octopus vulgaris), in waters around the United Kingdom. The findings suggest that coexistence may be maintained because of the lack of competition for E. cirrhosa against the seemingly declining O. vulgaris populations, and that habitat and temporal partitioning are the likely mechanisms. It is contemplated whether species misidentification may an important factor in masking the accuracy of population dynamics of co‐occurring octopus species, and, as such, potential uncertainty in octopus coexistence and any future fishery management decisions. It is confidently suggested that, currently, only two octopus species are resident to UK waters. Now, further studies should include diet partitioning to determine whether diet partitioning is a mechanism for E. cirrhosa and O. vulgaris coexistence, and monitoring may make us understand their population dynamics. [ABSTRACT FROM AUTHOR]

The East Asian common octopus (Octopus sinensis) is an economically important species among cephalopods. This species exhibits a strict dioecious and allogamous reproductive strategy, along with a phenotypic sexual dimorphism, where the third right arm differentiates into hectocotylus in males. However, our understanding of the molecular mechanisms that underlie sex determination and differentiation in this species remains limited. In the present study, we surveyed gene-expression profiles in the immature male and female gonads of O. sinensis based on the RNA-seq, and a total of 47.83 Gb of high-quality data were generated. Compared with the testis, we identified 8302 differentially expressed genes (DEGs) in the ovary, of which 4459 genes were up-regulated and 3843 genes were down-regulated. Based on the GO enrichment, many GO terms related to sex differentiation were identified, such as sex differentiation (GO: 0007548), sexual reproduction (GO: 0019953) and male sex differentiation (GO: 0046661). A KEGG classification analysis identified three conserved signaling pathways that related to sex differentiation, including the Wnt signaling pathway, TGF-β signaling pathway and Notch signaling pathway. Additionally, 21 sex-related DEGs were selected, of which 13 DEGs were male-biased, including Dmrt1, Foxn5, Foxj1, Sox30, etc., and 8 DEGs were female-biased, including Sox14, Nanos3, β-tubulin, Suh, etc. Ten DEGs were used to verify the expression patterns in the testis and ovary using the RT-qPCR method, and the results showed that the expression level shown by RT-qPCR was consistent with that from the RNA-seq, which confirmed the reliability of the transcriptome data. The results presented in this study will not only contribute to our understanding of sex-formation mechanisms in O. sinensis but also provide the foundational information for further investigating the molecular mechanisms that underline its gonadal development and facilitate the sustainable development of octopus artificial breeding. [ABSTRACT FROM AUTHOR]

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The posterior salivary gland of Octopus vulgaris is apocrine and has a discrete character in the animal kingdom. In general, studying the evolution of any toxic organism typically starts with an examination of its defense system, including the minute structures with similar organisms across various phyla in the animal kingdom. The posterior salivary gland of Octopus vulgaris consists of a thick gland wall with a contraction function for pushing the toxin through the gland duct and into the pass tube, which opens in a buccal mass. The posterior salivary gland of Octopus vulgaris secretes toxic saliva, which is thermostable liquid resistant to heat and has a darkened blue appearance when stained with bromophenol blue, more pronounced than the venom. The present gland consists of nine types of cells associated with a canal that transports the toxin from the posterior to anterior salivary glands. These glands are located in the middle of the gland and consist of a mixture of circular and longitudinal muscle fibers, respectively. The secretion of the present gland is considered analogous to the evolutionary progression from octopus to the cobra snake. In the cobra snake, there are two types of cells with thick walls that aid in the contraction of the gland to push the toxin outside the mouth. In octopuses, two small cells represent an early evolutionary stage observed in glands across the animal kingdom, as recorded in the earliest records. [ABSTRACT FROM AUTHOR]

Over the past decade, there has been a growing interest in common octopus aquaculture, prompted by several factors such as the increase in market demand, the decline in overall fisheries and the search for more sustainable food resources. Nevertheless, this interest has raised concerns about the potential impact of large-scale production and intensified farming practices in the future. This study aims to establish a baseline understanding of the natural microbial communities that inhabit skin mucus of the common octopus, describe its core microbiota, and assess the impact of captive rearing on these communities and animal welfare. The skin microbiome of wild-captured octopuses was compared with that of reared in aquaculture using 16S ribosomal RNA metabarcoding. The findings show that the core microbiota of octopus mucosal skin is dominated by the phyla Bacteroidota and Pseudomonadota, with Aurantivirga, Pseudofulvibacter, and Rubritalea being the most abundant genera. Despite differences in abundance, the microbiota composition and diversity between wild and aquaculture octopuses were similar. Wild samples had an enrichment of Gammaproteobacteria, including potentially pathogenic species such as Vibrio spp., Photobacterium swingsii, and Lactococcus garvieae, which were less prevalent or absent in aquaculture samples. KEGG functional pathways predictions indicated a higher enrichment in functional pathways related to xenobiotic remediation in wild samples, reflecting their need to adapt to a more variable and potentially contaminated environment. This is the first study to characterize the mucosal skin microbiome of the common octopus and to compare wild and aquaculture specimens. The results suggest that current aquaculture practices support animal welfare through the use of controlled hatchery environments and high-quality water conditions. These insights are valuable for the development of sustainable and responsible aquaculture practices, with the octopus microbiome serving as a potential biomarker for health status and animal welfare.

We present the description of defensive behavior in wild Octopus vulgaris against conger eel (Conger conger) attacks based on three video sequences recorded by recreational SCUBA divers in the eastern Atlantic off the coast of Galicia (NW Spain) and in the Cantabrian Sea (NW Spain). These records document common traits in defensive behavior: (1) the octopuses enveloped the conger eel's head to obscure its view; (2) they covered the eel's gills in an attempt to suffocate it; (3) they released ink; (4) the octopuses lost some appendages because of the fight. In the third video, the octopus did not exhibit the defensive behavior described in the first two videos due to an inability to utilize its arms in defense, and the conger eel's success in capturing octopuses is discussed. Additionally, both the cost that the octopus could face by losing some arms during the fight and whether the experience it acquires can be an advantage for future encounters are analyzed. The defensive behavior exhibited by octopuses in this study highlights their ability to survive in a hostile environment and serves as an example of the extensive repertoire of anti‐predator strategies employed by these cephalopods. [ABSTRACT FROM AUTHOR]

The melanin structure in Cephalopods comprises multi-compound structures, including Tyrosinase-A and Tyrosinase-B. These structures exhibit positivity for H&E stain in some stages and bromophenol blue stain in others. Other components are positive for H&E stains as amylase and peptides of holocrine comments, such as Gamma p.p.t and Gamma melodine, which are rich in ink of Octopus vulgaris and cause color blindness for prey during the predation process of animal. The Octopus vulgaris has numerous inking colors, such as brown and deep brown color, released during the escape from predation animals. During this process, the light falls on the skin, and melanin pigments give deep brown color by mixing the ink with amylase enzymes. The melanin mechanism in all organisms is similar to each other's in the animal kingdom except insects, where it is produced differently. Additionally, melanin pigments are only retained in the upper epidermis from bacterial reactions. The knowledge of the mechanism of melanin formations is highly important for treating dermatology diseases in humans and reducing the risk of skin cancer. [ABSTRACT FROM AUTHOR]

Cephalopods are harvested in increasingly large quantities but understanding how to control and manage their stocks, and tracking the routes of the consumption that exploits them, lag behind what has been developed for exploiting finfish. This review attempts to redress the imbalance by considering the status of the major cephalopod stock species and the traceability of cephalopod seafood along the trade value chain. It begins with a general overview of the most important exploited cephalopods, their stock status and their market. Four major cephalopod resources are identified: the three squid species Todarodes pacificus, Dosidicus gigas and Illex argentinus; and one species of octopus, Octopus vulgaris. The techniques and problems of stock assessment (to assess sustainability) are reviewed briefly and the problems and possible solutions for assessing benthic stock such as those of octopuses are considered. An example of a stock well managed in the long term is presented to illustrate the value of careful monitoring and management: the squid Doryteuthis gahi available in Falkland Islands waters. Issues surrounding identification, mislabelling and illegal, unreported and unregulated (IUU) fishing are then reviewed, followed by a discussion of approaches and techniques of traceability as applied to cephalopods. Finally, some of the mobile apps currently available and in development for tracking seafood are compared. This review concludes with observations on the necessity for the strengthening and international coordination of legislation, and more rigorous standards for seafood labelling and for taxonomic curation of DNA sequences available in public databases for use in seafood identification. [ABSTRACT FROM AUTHOR]

Growing knowledge of the host-microbiota of vertebrates has shown the prevalence of sex-specific differences in the microbiome. However, there are virtually no studies assessing sex-associated variation in the microbiome of cephalopods. Here we assess sex-specific variation in the common octopus (Octopus vulgaris) skin microbiome using amplicon sequencing targeting the V4 hypervariable region of prokaryote 16S rRNA genes. Skin and mantle-associated mucus was collected from wild adult individuals of common Octopus (Octopus vulgaris) (9 males and 7 females of similar size). There were no significant differences in the alpha diversity of microbial communities associated with skin or mantle mucosa between sexes. However, our results clearly indicate that adult octopus males and females have a distinct microbial community composition in both skin and mantle associated mucus communities, with female microbiome being dominated by Firmicutes (48.1%), while that of males contained a majority of Proteobacteria (60.5%), with Firmicutes representing only 3.30%, not finding significant differentiation in the microbial communities between the tissues explored. The dominance of different taxa in the skin of O. vulgaris females and males (e.g., Mycoplasmatales and Lactococcus in females and Rhizobiales and Rhodobacteriales in males) suggests a sex-specific symbiosis in which those microbes benefit from easy access to distinct substrates present in female and male skin, respectively. Given the lack of differences in size between specimens of both sexes in this study, we hypothesize differences in hormone profile, as well as behavioral or ecological differences between sexes in the wild, as the main drivers of microbiome differentiation between sexes. Most knowledge of cephalopod microbiota is limited to the digestive tract and the reproductive system. However, cephalopod skin is an organ with a plethora of functions. This is a first attempt to characterize cephalopod skin microbiota and determine sex influence on it. [ABSTRACT FROM AUTHOR]

Cephalopoda classes are highly valued for their culinary appeal and nutritional value. However, their perishability necessitates careful handling and optimal storage conditions to maintain their quality. This study aimed to investigate the influence of storage temperature on the quality attributes and sensory properties of five commonly consumed cephalopod types: whole squid, whole squid tubes, octopus, Loligo spp. (squid tubes), and Sepia spp. (cuttlefish tubes) classified in five different species (Loligo vulgaris (European squid), Loligo gahi (Japanese squid), Octopus vulgaris (Octopus), Sepia officinalis (Cuttlefish) and Illex argentinus (Argentine shortfin squid)). Lower temperatures (-23°C) significantly prolonged shelf life, delaying spoilage onset and preserving taste. The product named calamar had the fastest spoilage rate, followed by whole squid and tube squid, while Octopus had the slowest spoilage rate. Appropriate storage practices are vital for ensuring the freshness and palatability of frozen cephalopods. [ABSTRACT FROM AUTHOR]

Cephalopods are well known for their cognitive capabilities and unique behavioural repertoires. Yet, certain life strategies and behaviours are still not fully understood. For instance, coastal octopuses have been documented (mainly through citizen science and TV documentaries) to occasionally leave the water and crawl in intertidal areas. Yet, there is a complete lack of knowledge on this behaviour's physiological and biochemical basis. Within this context, this study aimed to investigate, for the first time, physiological (routine and maximum metabolic rates and aerobic scope) and biochemical (i.e., antioxidant enzymes activities, heat shock protein and ubiquitin levels, DNA damage, lipid peroxidation) responses of the common octopus, Octopus vulgaris, to emersion. The octopuses' physiological performance was determined by measuring metabolic rates in different emersion treatments and biochemical markers. The size-adjusted maximum metabolic rates (MMRadj) of octopuses exposed to 2:30 min of air exposure followed by re-immersion did not differ significantly from the MMRadj of the chased individuals (control group). Yet, most biochemical markers revealed no significant differences among the different emersion treatments. Our findings showed that O. vulgaris could tolerate exposure to short-term emersion periods due to an efficient antioxidant machinery and cellular repair mechanisms. Alongside, we argue that the use of atmospheric air through the mucus-covered gills and/or cutaneous respiration may also help octopus withstand emersion and crawling on land. [ABSTRACT FROM AUTHOR]

Background: The Octopus vulgaris species complex consists of numerous morphologically similar but genetically distinct species. The current publicly available mitogenome of this species has been generated from a specimen collected from Tsukiji Fish Market, Tokyo, Japan. Octopus from the northwestern Pacific Ocean are now considered to be a separate species, Octopus sinensis. For this reason, we hypothesised that the current record of O. vulgaris was sequenced from a specimen of O. sinensis. Here, we sequenced the first complete mitogenome of a specimen of Octopus vulgaris sensu stricto that was collected from the species’ confirmed distribution areas in northeastern Atlantic. Methods and results: The complete mitogenome was assembled de novo and annotated using 250 bp paired-end sequences. A single circular contig 15,655 bp in length with a mean read coverage of 1089 reads was reconstructed. The annotation pipeline identified 13 protein-coding genes (PCGs), 22 transfer RNAs (tRNA) and two ribosomal RNAs. A maximum likelihood phylogenetic tree recovered the assembled mitogenome as the sister taxon of a monophyletic group comprising O. sinensis and the previously published mitogenome of “O. vulgaris” from Japan. This confirms that the latter was a Japanese specimen of O. sinensis. Conclusion: The mitogenome sequenced here is the first to be published for Octopus vulgaris sensu stricto. It represents an important first step in genetics-informed research on the evolution, conservation, and management of this commercially important species. [ABSTRACT FROM AUTHOR]

Background: The Octopus vulgaris species complex consists of numerous morphologically similar but genetically distinct species. The current publicly available mitogenome of this species has been generated from a specimen collected from Tsukiji Fish Market, Tokyo, Japan. Octopus from the northwestern Pacific Ocean are now considered to be a separate species, Octopus sinensis. For this reason, we hypothesised that the current record of O. vulgaris was sequenced from a specimen of O. sinensis. Here, we sequenced the first complete mitogenome of a specimen of Octopus vulgaris sensu stricto that was collected from the species' confirmed distribution areas in northeastern Atlantic. Methods and results: The complete mitogenome was assembled de novo and annotated using 250 bp paired-end sequences. A single circular contig 15,655 bp in length with a mean read coverage of 1089 reads was reconstructed. The annotation pipeline identified 13 protein-coding genes (PCGs), 22 transfer RNAs (tRNA) and two ribosomal RNAs. A maximum likelihood phylogenetic tree recovered the assembled mitogenome as the sister taxon of a monophyletic group comprising O. sinensis and the previously published mitogenome of "O. vulgaris" from Japan. This confirms that the latter was a Japanese specimen of O. sinensis. Conclusion: The mitogenome sequenced here is the first to be published for Octopus vulgaris sensu stricto. It represents an important first step in genetics-informed research on the evolution, conservation, and management of this commercially important species. [ABSTRACT FROM AUTHOR]

Simple Summary: Here, we investigated how Octopus vulgaris approached and solved a problem required for obtaining food from a puzzle box. We also explored the relationship between individual octopuses' problem-solving abilities and various behavioural characteristics (e.g., their interest in novel objects), and biotic and environmental factors (age, season, and site of capture). We found that octopuses more inclined to approach new objects were quicker to approach the puzzle box and more likely to succeed in opening it, but they did not reach the solution before other individuals. This suggests that an excessive inclination towards novelty could hinder problem-solving efficiency. The study also revealed that the season and the fishing site are important drivers of octopuses' behavioural differentiation. Our findings offer valuable insights into the individuality of octopuses. By presenting individual Octopus vulgaris with an extractive foraging problem with a puzzle box, we examined the possible correlation between behavioural performances (e.g., ease of adaptation to captive conditions, prevalence of neophobic and neophilic behaviours, and propensity to learn individually or by observing conspecifics), biotic (body and brain size, age, sex) and abiotic (seasonality and place of origin) factors. We found more neophilic animals showing shorter latencies to approach the puzzle box and higher probability of solving the task; also, shorter times to solve the task were correlated with better performance on the individual learning task. However, the most neophilic octopuses that approached the puzzle box more quickly did not reach the solution earlier than other individuals, suggesting that strong neophilic tendency may lead to suboptimal performance at some stages of the problem-solving process. In addition, seasonal and environmental characteristics of location of origin appear to influence the rate of expression of individual traits central to problem solving. Overall, our analysis provides new insights into the traits associated with problem solving in invertebrates and highlights the presence of adaptive mechanisms that promote population-level changes in octopuses' behavioural traits. [ABSTRACT FROM AUTHOR]

Cephalopods are emerging animal models and include iconic species for studying the link between genomic innovations and physiological and behavioral complexities. Coleoid cephalopods possess the largest nervous system among invertebrates, both for cell counts and brain-to-body ratio. Octopus vulgaris has been at the center of a long-standing tradition of research into diverse aspects of cephalopod biology, including behavioral and neural plasticity, learning and memory recall, regeneration, and sophisticated cognition. However, no chromosome-scale genome assembly was available for O. vulgaris to aid in functional studies. To fill this gap, we sequenced and assembled a chromosome-scale genome of the common octopus, O. vulgaris. The final assembly spans 2.8 billion basepairs, 99.34% of which are in 30 chromosome-scale scaffolds. Hi-C heatmaps support a karyotype of 1n = 30 chromosomes. Comparisons with other octopus species' genomes show a conserved octopus karyotype and a pattern of local genome rearrangements between species. This new chromosome-scale genome of O. vulgaris will further facilitate research in all aspects of cephalopod biology, including various forms of plasticity and the neural machinery underlying sophisticated cognition, as well as an understanding of cephalopod evolution. [ABSTRACT FROM AUTHOR]

Simple Summary: Anaesthetising invertebrates is a welfare issue, but because there are so many different invertebrates (97% of all animal species), it is of the utmost importance to work out the most appropriate way to anaesthetise each group or even particular species of animals. In order to reduce stress and pain to the animals, clinical anaesthetics offer a standardised approach, given their known and well-studied effects at both system and cellular levels. Here, we show that the clinical anaesthetic isoflurane (1%), often used by veterinarians, can anaesthetise octopuses quickly and efficiently when used in conjunction with 1% magnesium chloride, which acts as a muscle relaxant. Recovery is equally quick, and the whole process from anaesthetisation to recovery is completed in 30 to 35 min, minimising animal stress. A wide variety of substances have been used to anaesthetise invertebrates, but many are not anaesthetics and merely incapacitate animals rather than preventing pain. In essence, the role of an ideal general anaesthetic is to act as a muscle relaxant, an analgesic, an anaesthetic, and an amnesic. To achieve all these properties with a single substance is difficult, and various adjuvants usually need to be administered, resulting in a cocktail of drugs. In a clinical setting, the vast majority of patients are unaware of surgery being carried out and have no memory of it, so they can claim to have felt no pain, but this is much more difficult to demonstrate in invertebrates. Here, we show that 1% MgCl2, a muscle relaxant, is a useful adjuvant for the clinical anaesthetic isoflurane on Octopus vulgaris when applied alone in seawater for 10 min before the clinical anaesthetic. After this, full anaesthesia can be achieved in 5 min using 1% isoflurane insufflated into the saline still containing MgCl2. Full recovery takes place rapidly in about 10 to 15 min. The depth of anaesthesia was monitored using changes in respiratory rate, chromatophore pattern, and withdrawal movements of the arms and siphon. This methodology reduces stress on the animal and minimises the quantity of anaesthetic used. [ABSTRACT FROM AUTHOR]

Achieving complex behavior in soft-bodied animals is a hard task, because their body morphology is not constrained by a fixed number of jointed elements, as in skeletal animals, and thus the control system has to deal with practically an infinite number of control variables (degrees of freedom). Almost 30 years of research on Octopus vulgaris motor control has revealed that octopuses efficiently control their body with strategies that emerged during the adaptive coevolution of their nervous system and body morphology. In this minireview, we highlight principles of embodied organization that were revealed by studying octopus motor control, and that are used as inspiration for soft robotics. We describe the evolved solutions to the problem, implemented from the lowest level, the muscular system, to the network organization in higher motor control centers of the octopus brain. We show how the higher motor control centers, where the sensory–motor interface lies, can control and coordinate limbs with large degrees of freedom without using body-part maps to represent sensory and motor information, as they do in vertebrates. We demonstrate how this unique control mechanism, which allows efficient control of the body in a large variety of behaviors, is embodied within the animal's body morphology. Hochner et al. review our knowledge of motor control in octopus, highlighting the principles of embodied organization where unique solutions from the muscular system to the network organization of the octopus brain allow efficient and flexible control of the body in the wide variety of behaviors manifested by the animal. [ABSTRACT FROM AUTHOR]

This study focused on the recovery of valuable lipid compounds from octopus (Octopus vulgaris) by-products. Extraction conditions of total lipids (TLs), phospholipids (PLs), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) were optimized by employing a Simplex-Lattice design; for it, different relative concentrations of three low-toxicity solvents (ethanol, acetone, and ethyl acetate) were considered. The optimization process was also addressed in reference to fatty acid (FA) ratios (total polyunsaturated FAs/total saturated FAs and total ω3 FAs/total ω6 FAs). The variance analysis of multiple regression data demonstrated that the quadratic model was significant (p < 0.05) for TL, PL, and DHA values and the ω3/ω6 ratio. As a result, the following optimized values were obtained: 113.8 g·kg−1 dry by-products (TLs), 217.3 g·kg−1 lipids (PLs), 22.55 g·100 g−1 total FAs (DHA), and 3.70 (ω3/ω6 ratio). According to the model developed, optimized values were shown to correspond to the following relative solvent concentrations (ethanol/acetone/ethyl acetate): 0.46/0.00/0.54, 0.93/0.07/0.00, 0.83/0.17/0.00, and 0.64/0.00/0.36, respectively. Comparison to yields obtained by the conventional chloroform/methanol method was carried out. A novel strategy based on the employment of low-toxicity solvents is proposed for the extraction of valuable lipid constituents from octopus waste. A different solvent ratio would be necessary according to the lipid compound concerned. [ABSTRACT FROM AUTHOR]

0ctoGANN is an experimental fiction, operating through multi-sensory imagination, that draws on my experiences of freediving in the Great African Kelp Forest off the coast of Capetown – home to the common octopus – together with an ongoing commitment to refiguring AI. The writing emerges from imagining into the lifeworld of the octopus, made possible by my immersion in the ocean flows and surges. It is a call to (western) human-centric perspectives to embrace knowledge-gathering through embodied intelligence, and to consider how AI might be trained on the decentralized distributed somatic tendencies of the octopus rather than on current corporate marketing/surveillance agendas. It is also a paean to this protean, incoherent (to humans) and experimental creature, living in a constant state of change and fluidity. 0ctoGANN is certainly an expression of hope for the contemporary world, though not necessarily human. [ABSTRACT FROM AUTHOR]

Considering the need for developing new senior-friendly processed seafood, this study aimed to develop octopus pulpo with high preference and excellent quality characteristics for elderly individuals by optimizing the vinegar immersion and sous vide softening treatment conditions for octopus (Octopus vulgaris) arms. The optimal sous vide heating temperature (70.0–100.0 °C), time (69.5–170.5 min), and vinegar concentration (0.2–0.8%) were established using response surface methodology (RSM). The pulpo prototype was produced using an octopus arm softened under optimal conditions and seasoned with a potato and olive oil sauce. The physicochemical and nutritional properties of the prototype were evaluated, followed by sensory evaluation and safety assessments. The hardness of softened octopuses obtained by 0.48% vinegar immersion and sous vide treatment (84.3 °C, 139.8 min), determined using RSM, was 394.5 × 1000 N/m2, showing a reduction of 83.0%; this was confirmed by electron microscopic observation. The texture of the pulpo prototype with softened octopus arms showed the highest preference (8.4 points) and high physicochemical and nutritional properties. Overall, the octopus pulpo a La Gallega prototype produced using texture-modified octopus arms was suitable for consumption by elderly people with chewing disorders and could help improve their quality of life. [ABSTRACT FROM AUTHOR]

Antipredator behavior of the paralarval stages of merobenthic octopuses is largely unknown. Reported here is an investigation of the behavioral response of Octopus sinensis paralarvae to the sympatric predator fish Girella punctata. Fishes of this species exhibited predatory behavior by engulfing individual paralarvae, but most fishes almost immediately rejected the paralarva from the mouth. No paralarvae died after being engulfed and ejected. The number of such temporary engulfings of a paralarva by a fish during the test period (10 min) decreased with the increase in the number of times a paralarva was engulfed. The frequency of engulfing attacks by the fish also declined. The paralarvae did not eject ink before being engulfed, but 43% of the paralarvae exhibited inking immediately after ejection from the fish's mouth. The fishes ingested the ink masses released by the paralarvae, and the proportion of fish ingesting the ink masses increased with increasing experience of encountering the ink. When the paralarvae ejected ink, the time interval between first engulfing and subsequent engulfing increased, apparently in relation to distraction of the fish by the ink. These results suggest that paralarvae have an antipredatory mechanism which causes predatory fish to eject them after they have been engulfed. In addition, the paralarvae use the stimulus of being ejected from the mouth of a fish as a cue for ink ejection. The ink mass may be attractive to the fish as a food item because of its potential action as a phagomimetic distraction, enabling the paralarvae to escape. [ABSTRACT FROM AUTHOR]

The United Nations (UN) Decade of Ocean Science highlights a need to improve the way in which scientific results effectively inform action and policies regarding the ocean. Our research contributes to achieving this goal by identifying practical actions, barriers, stakeholder contributions and resources required to increase the sustainability of activities carried out in the context of artisanal fisheries to meet UN Sustainable Development Goals (SDG) and International Year of Artisanal Fisheries and Aquaculture (IYAFA) Global Action Plan (GAP) Pillar targets. We conducted a novel 'social value chain analysis' via a participatory workshop to elicit perspectives of value chain actors and fisheries stakeholders associated with two Spanish artisanal common octopus (Octopus vulgaris) fisheries (western Asturias—Marine Stewardship Council [MSC] certified, and Galicia—non-MSC certified) about their priorities regarding sustainable octopus production and commercialization. Our adapted Rapfish sustainability framework emphasised the importance of economic, environmental, ethical, institutional, social, and technological indicators to different actors across the value chain. We mapped participants' shared sustainability priorities (e.g. integrated fisheries management, knowledge-based management, product traceability) to six Rapfish indicators, seven IYAFA Pillars and twelve SDGs to reveal how our results can inform ocean policy and actions. This identified how certification incentives and other cooperative approaches can facilitate environmental, economic and social sustainability (e.g. value-added products, price premiums for producers, gender inclusive organisations); support IYAFA priority outcomes (raised awareness, strengthened science-policy interface, empowered stakeholders, partnerships); and help to achieve UN SDG targets (e.g. SDG 14.b, SDG 17.17). The results can inform actors, stakeholders and policymakers about how different actors contribute to efforts to achieve the SDGs and how to manage priorities for sustainable actions within artisanal fisheries and their value chains. We recommend inclusive and equitable participatory knowledge transfer and governance platforms as part of the UN Decade of Ocean Science and beyond where participants can create theories of change towards sustainability involving the development of multi-sectoral ocean policies framed at the level of the value chain and supported by appropriate governance structures. [ABSTRACT FROM AUTHOR]

Simple Summary: The artisanal octopus fishery is a great tradition and has a large economic impact in Northern Spain. Despite its importance, there is scarce genetic information for this exploited population. The uniqueness of an exploited population and the effects that exploitation may have on its long-term survival is essential information that can be obtained by studying the past and current spatial and temporal genetic patterns. The mitochondrial DNA is used here as a genetic tool to gain insight into Northeast Atlantic octopus populations and their evolutionary history. Although it is not sensitive enough to detect differences in nearby populations, it allows us to differentiate the two main lineages that originated during the Quaternary glaciations. One of the lineages is present exclusively in northern latitudes and the other mainly in the south, although, for the first time, its presence is demonstrated also in the north of the Iberian Peninsula. This implies a more continuous distribution than previously thought for this lineage. We also detect temporal changes in the distribution of the two lineages in contact zones. These changes seem to be associated with the effect of changing oceanographic conditions. Future studies on these associations could be of interest for fisheries in the scenario of global climate change. Octopus vulgaris is one of the most harvested octopus species in the world. In the Iberian Peninsula, there are several small-scale fisheries that have a long-term tradition of harvesting octopus. The Asturias fleet (in Northern Spain) has an internationally recognized MSC label for its exploitation. Of concern, genetic assessments of exploited stocks are currently scarce, which could prevent the implementation of adequate managing strategies. We use two mitochondrial regions (cytochrome oxidase subunit 1 and control region) to analyze the genetic status and evolutionary events that conditioned octopus populations' characteristics in the Northeastern Atlantic. A total of 90 individuals were sampled from three different localities in the Iberian Peninsula as well as a location in Macaronesia. Temporal genetic analyses on Asturias and Algarve populations were also performed. Results indicated the absence of fine spatial genetic structuring but showed the Canary Islands (in Macaronesia) as the most distinct population. Our analyses detected two distinct clades, already described in the literature, but, for the first time, we confirmed the presence of the α-southern haplogroup in the Northern Iberian Peninsula. This result indicates a more continuous cline for the distribution of these two haplogroups than previously reported. Temporal changes in the distribution of both haplogroups in contact zones were also detected. [ABSTRACT FROM AUTHOR]

This retrospective study examines pathologic findings in 593 captive cephalopods (340 octopuses, 130 cuttlefish, 33 squid, and 90 nautiluses; 22 species in total) submitted to International Zoo Veterinary Group Pathology between May 2003 and August 2022. Common octopus, European common cuttlefish, hummingbird bobtail squid, and chambered nautilus were the most numerous species from the included orders of Octopoda, Sepiida, Sepiolida, and Nautilida, respectively. Commonly identified conditions included coccidiosis and renal dicyemid mesozoan infection in octopuses, amebiasis in squid, bacterial infections in cuttlefish, and idiopathic multisystemic inflammatory disease in nautiluses. Coccidiosis was most frequent in common octopuses, giant Pacific octopuses, and California 2-spot octopuses (present in 68.4%, 46.3%, and 23.8% of these species, respectively) and was the attributed cause of death in 32.3%, 36.0%, and 60.0% of such cases, respectively. Ulcerative dermatitis (UD) was common, affecting squid, cuttlefish, and octopuses, while many nautiluses exhibited black shell disease and/or UD. Notable differences in the prevalence of UD were detected between laboratory and aquaria-housed decapodiforms; 52.2% for laboratory squid versus 20.0% in aquaria; 51.3% in laboratory cuttlefish versus 11.0% in aquaria. All octopuses and nautiluses in the study were derived from aquaria. Semelparity-associated death in Coleoidea species was identified in 22.4% of octopuses, 11.5% of cuttlefish, and 6.1% of squid. This report aims to provide an overview and reassessment of species-specific disease patterns under aquarium and laboratory management as a starting point for future developments in husbandry and disease investigation. [ABSTRACT FROM AUTHOR]

Parasitism of cephalopods is common, including infection with Aggregata spp., Ichthyobodo spp., dicyemids, cestodes of the orders Tetraphyllidea and Trypanorhynchidea, and various crustaceans. Cestodiasis in octopuses is reported, although a full histologic description of lesions has not been previously described. Cestodiasis was identified in 10 octopuses of 4 different species, which included 4 common octopuses (Octopus vulgaris), 3 Caribbean reef octopuses (Octopus briareus), 2 two-spot octopuses (Octopus bimaculoides), and 1 giant Pacific octopus (Enteroctopus dofleini). Larval cestodes were present in the cecum (n = 5), intestines (n = 4), digestive gland (n = 3), chitinous alimentary tract (n = 2), renal appendage (n = 1), and salivary duct (n = 1). In 5 cases, larval cestodes invaded tissue and were associated with hemocytic inflammation and tracts of necrotic tissue in the intestines (n = 3), digestive gland (n = 3), and/or renal appendage (n = 1). When present in the chitinous alimentary tract (esophagus, stomach) or cecum, larval cestodes were in the central lumen and not associated with lesions. One adult cestode was identified in the mantle cavity and was not associated with lesions. Other common concurrent parasitic infections included enteric Aggregata spp. infection, branchial Rickettsia-like organism infection, enteric nematodiasis, and an arthropod-associated branchitis. [ABSTRACT FROM AUTHOR]

The article advocates for the U.S. Congress to pass the OCTOPUS Act to prevent the establishment of commercial octopus farms, emphasizing that these farms cannot meet welfare standards and are unsustainable. Topics discussed include the ethical concerns of octopus captivity, the environmental impact of farming carnivorous species, and the motivations behind the demand for exotic meats.

Here, we present the first analysis of the connectome of a small volume of the Octopus vulgaris vertical lobe (VL), a brain structure mediating the acquisition of long-term memory in this behaviorally advanced mollusk. Serial section electron microscopy revealed new types of interneurons, cellular components of extensive modulatory systems, and multiple synaptic motifs. The sensory input to the VL is conveyed via~1.8 × 106 axons that sparsely innervate two parallel and interconnected feedforward networks formed by the two types of amacrine interneurons (AM), simple AMs (SAMs) and complex AMs (CAMs). SAMs make up 89.3% of the~25 × 106 VL cells, each receiving a synaptic input from only a single input neuron on its non-bifurcating primary neurite, suggesting that each input neuron is represented in only~12 ± 3.4SAMs. This synaptic site is likely a ‘memory site’ as it is endowed with LTP. The CAMs, a newly described AM type, comprise 1.6% of the VL cells. Their bifurcating neurites integrate multiple inputs from the input axons and SAMs. While the SAM network appears to feedforward sparse ‘memorizable’ sensory representations to the VL output layer, the CAMs appear to monitor global activity and feedforward a balancing inhibition for ‘sharpening’ the stimulus-specific VL output. While sharing morphological and wiring features with circuits supporting associative learning in other animals, the VL has evolved a unique circuit that enables associative learning based on feedforward information flow. [ABSTRACT FROM AUTHOR]

The distribution of octopuses within the Octopus vulgaris species complex remains inadequately understood. Species determination can be complex and involves characterizing a specimen’s physical features and comparing its genetic makeup to other populations. In this study, we present the first genetic confirmation of Octopus insularis (Leite and Haimovici, 2008) inhabiting the coastal waters of the Florida Keys, United States. We employed visual observations to identify species-specific body patterns of three wild-caught octopuses and used de novo genome assembly to confirm their species. All three specimens exhibited a red/white reticulated pattern on their ventral arm surface. Two specimens displayed body pattern components of deimatic display (white eye encircled by a light ring, with darkening around the eye). All visual observations were consistent with distinguishing features of O. insularis. We then compared mitochondrial subunits COI, COIII, and 16S in these specimens across all available annotated octopod sequences, including Sepia apama (Hotaling et al., 2021) as a control outgroup taxon. For species exhibiting intraspecific genomic variation, we included multiple sequences from geographically distinct populations. Laboratory specimens consistently clustered into a single taxonomic node with O. insularis. These findings confirm O. insularis presence in South Florida and suggest a more extensive northern distribution than previously assumed. Whole genome Illumina sequencing of multiple specimens enabled taxonomic identification with well-established DNA barcodes while also generating the first de novo full assembly of O. insularis. Furthermore, constructing and comparing phylogenetic trees for multiple conserved genes is essential for confirming the presence and delineation of cryptic species in the Caribbean. [ABSTRACT FROM AUTHOR]

This study presents the results of the examination of cephalopod remains extracted from the digestive tract of 40 loggerhead turtles, Caretta caretta, stranded along the Campanian coasts (Southern Italy, eastern Tyrrhenian Sea). We retrieved the remains of 23 cephalopods from 16 turtles (frequency of occurrence = 40%). They belonged to Sepia officinalis (19 specimens) and Octopus vulgaris (2 specimens), both of them benthic neritic species, and Histioteuthis reversa (2 specimens), an oceanic species. Accordingly, loggerheads appear to feed both on the bottom, seemingly in shallow waters, and in the open seawater column; both on muscular items (S. officinalis and O. vulgaris) and ammoniacal ones (H. reversa). This is the first record of H. reversa as a prey of the loggerhead turtle. [ABSTRACT FROM AUTHOR]

Simple Summary: Octopuses, like other cephalopods, have specific behaviors that correspond to a sequence of body patterns. Each pattern is the result of various components that, when performed simultaneously, have different outcomes. The vast repertoire in pattern production is associated with the complexity and variety of environmental enrichment. The greater the complexity of the environment, the greater the possibility of observing a wide variety of patterns. In this study, we evaluated how different environmental conditions affect subjects of Octopus vulgaris maintained in an aquaculture system through the observation of major body patterns. The results showed that octopuses kept in an enriched environment showed significantly more body patterns and gained significantly more weight than the subjects kept in a basic environment. The body patterns manifested by the octopuses maintained in a basic environment were similar to those exhibited under situations of hostility and inter/intra-specific conflict. They did not interact much with the surrounding habitat, the conspecifics, or the operator. Therefore, environmental enrichment is recommended for the individuals of this species that are kept in a recirculating aquaculture system (RAS). Octopus vulgaris is a commercially valuable species. It is overexploited in the natural environment and is considered to be an innovative species for aquaculture. However, large-scale farming is generally designed only based on economic requirements, disregarding any form of enrichment that induces the natural behavior of aquatic species. Although many studies have shown the influence of environmental enrichment on terrestrial vertebrates, fish, and cephalopod mollusks, information on the effect of environmental enrichment on the body patterns of O. vulgaris is limited. Therefore, in this study, we assessed how different environmental conditions (Basic vs. Enriched) affect sub-adults of O. vulgaris kept in recirculation systems, through qualitative–quantitative studies of the main body patterns and their potential application in the commercial production of this species. The results indicated that octopuses kept in the enriched environment showed several body patterns and gained a significantly higher weight than those kept in the basic environment. The body patterns displayed by the individuals kept in the basic environment were similar to those exhibited under situations of hostility and inter/intra-specific conflict. Hence, the environment of octopuses needs to be enriched, especially for the large-scale production of this species. [ABSTRACT FROM AUTHOR]

Our knowledge of the diet of wild octopus paralarvae, Octopus vulgaris, is restricted to the first 2 weeks of its planktonic phase when they are selective hunters found near the coastline. These small paralarvae, bearing only three suckers per arm, are transported by oceanic currents from the coast towards offshore waters, where they complete the planktonic phase over 2 months. Here, we have investigated the trophic ecology of O. vulgaris paralarvae in two contrasting upwelling sub-regions of the Iberian Canary current (ICC) eastern boundary upwelling system and have evaluated dietary change as paralarvae develop (inferred by counting the number of suckers per arm, ranging from three to 15) along the coastal-oceanic gradient during their planktonic phase. Using high-throughput amplicon sequencing, we have characterised the diet of 100 paralarvae collected along the Northwest Iberian Peninsula (n = 65, three to five suckers per arm) and off the west coast of Morocco (n = 35, three to 15 suckers per arm), identifying up to 87 different prey species. The diet of paralarvae varied along the ICC, with crabs (53.4%), siphonophores (12.2%), copepods (12.3%), cnidarians (8.4%) and pteropods (3.7%) accounting for 90% of the variability detected off NW Iberian Peninsula, whereas off W Morocco, crabs (46.2%), copepods (23.1%), cnidarians (12.9%), krill (9.3%) and fishes (4.2%) explained 95.6% of the variability observed using frequency of observance (FOO%) data. Ontogenetic changes in the diet based on groups of paralarvae with similar numbers per arm were evidenced by the decreasing contribution of coastal meroplankton and an increase in oceanic holoplankton, including siphonophores, copepods, pteropods and krill. Trophic niche breadth values ranged from 0.06 to 0.67, with averaged values ranging from 0.23 to 0.33 (generalist = 1 and specialist = 0), suggesting that O. vulgaris paralarvae are selective predators through their ontogenetic transition between coastal and oceanic environments. [ABSTRACT FROM AUTHOR]

Octopus vulgaris is a cephalopod mollusk and an active marine predator that has been at the center of a number of studies focused on the understanding of neural and biological plasticity. Studies on the machinery involved in e.g., learning and memory, regeneration, and neuromodulation are required to shed light on the conserved and/or unique mechanisms that these animals have evolved. Analysis of gene expression is one of the most essential means to expand our understanding of biological machinery, and the selection of an appropriate set of reference genes is the prerequisite for the quantitative real-time polymerase chain reaction (qRT-PCR). Here we selected 77 candidate reference genes (RGs) from a pool of stable and relatively high-expressed transcripts identified from the fulllength transcriptome of O. vulgaris, and we evaluated their expression stabilities in different tissues through geNorm, NormFinder, Bestkeeper, Delta-CT method, and RefFinder. Although various algorithms provided different assemblages of the most stable reference genes for the different kinds of tissues tested here, a comprehensive ranking revealed RGs specific to the nervous system (Ov-RNF7 and Ov-RIOK2) and Ov-EIF2A and Ov-CUL1 across all considered tissues. Furthermore, we validated RGs by assessing the expression profiles of nine target genes (Ov-Naa15, Ov-Ltv1, Ov-CG9286, Ov-EIF3M, Ov-NOB1, Ov-CSDE1, Ov-Abi2, Ov-Homer2, and Ov-Snx20) in different areas of the octopus nervous system (gastric ganglion, as control). Our study allowed us to identify the most extensive set of stable reference genes currently available for the nervous system and appendages of adult O. vulgaris. [ABSTRACT FROM AUTHOR]

Merobenthic octopods like Octopus vulgaris undergo a transitional period between the planktonic and benthic phases, known as settlement stage. In this work, three sub-stages ("pre-settlement", "settlement" and "post-settlement") have been defined based on morphological, anatomical, and behavioural changes. At the end of the planktonic phase advanced paralarvae are transparent with 65–80 chromatophores, iridophores covering eyes and digestive system, Kölliker organs, circular pupils, ~ 20 suckers per arm (spa), and mantle length (ML) bigger than total length (TL; ML/TL > 60%). The "pre-settlement" sub-stage (ML/TL from 65 to 55%, ~ 20–25 spa) is marked by the onset of clinging reflexes, where the pre-settlers touch the walls and bottom of the tank and start crawling clumsily. Morphologically, they are transparent with increased chromatophores along the arms and iridophores around the eyes and head. During the "settlement" sub-stage (~ 55–48% ML/TL, ~ 25–35 spa) there is an exponential increase of chromatophores in the dorsal area of head and mantle, and the settlers show strong negative phototaxis, crawling for shelter when disturbed. The skin is still transparent but new chromatic cells (leucophores) develop and Kölliker organs are almost lost. During the "post-settlement" sub-stage (~ 48–40% ML/TL, > 35 spa) the post-settlers display very fast and coordinated movements, have horizontal pupils, and develop the "eye-bar". The chromatic cells keep increasing exponentially, giving a pale appearance to the skin. The beginning of the benthic phase in O. vulgaris juveniles is marked by the presence of skin sculptural components (papillae) and a complex display of chromatic, postural, and cryptic patterns. [ABSTRACT FROM AUTHOR]

The common octopus is a cephalopod species subject to active fisheries, with great potential in the aquaculture and food industry, and which serves as a model species for biomedical and behavioral studies. The analysis of the skin mucus allows us to study their health in a non-invasive way, by using a hardly exploited discard of octopus in the fishing sector. A shotgun proteomics approach combined with liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) using an Orbitrap-Elite instrument was used to create a reference dataset from octopus skin mucus. The final proteome compilation was investigated by integrated in-silico studies, including Gene Ontology (GO), the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, network studies, and prediction and characterization analysis of potential bioactive peptides. This work presents the first proteomic analysis of the common octopus skin mucus proteome. This library was created by merging 5937 identified spectra of 2038 different peptides. A total of 510 non-redundant proteins were identified. Obtained results show proteins closely related to the defense, which highlight the role of skin mucus as the first barrier of defense and the interaction with the environment. Finally, the potential of the bioactive peptides with antimicrobial properties, and their possible application in biomedicine, pharmaceutical, and nutraceutical industry was addressed. [ABSTRACT FROM AUTHOR]

The high demand and economic relevance of cephalopods make them prone to food fraud, including related to harvest location. Therefore, there is a growing need to develop tools to unequivocally confirm their capture location. Cephalopod beaks are nonedible, making this material ideal for traceability studies as it can also be removed without a loss of commodity economic value. Within this context, common octopus (Octopus vulgaris) specimens were captured in five fishing areas along the Portuguese coast. Untargeted multi‐elemental total X‐ray fluorescence analysis of the octopus beaks revealed a high abundance of Ca, Cl, K, Na, S, and P, concomitant with the keratin and calcium phosphate nature of the material. We tested a suite of discrimination models on both elemental and spectral data, where the elements contributing most to discriminate capture location were typically associated with diet (As), human‐related pressures (Zn, Se, and Mn), or geological features (P, S, Mn, and Zn). Among the six different chemometrics approaches used to classify individuals to their capture location according to their beaks' element concentration, classification trees attained a classification accuracy of 76.7%, whilst reducing the number of explanatory variables for sample classification and highlighting variable importance for group discrimination. However, using X‐ray spectral features of the octopus beaks further improved classification accuracy, with the highest classification of 87.3% found with partial least‐squares discriminant analysis. Ultimately, element and spectral analyses of nonedible structures such as octopus beaks can provide an important, complementary, and easily accessible means to support seafood provenance and traceability, whilst integrating anthropogenic and/or geological gradients. [ABSTRACT FROM AUTHOR]

Consumer expectations regarding the quality of octopus are often frustrated and dissatisfaction is frequent, namely due to the excessive reduction in weight after cooking. Therefore, a rapid and non-destructive method based in time domain reflectometry (TDR) was developed for the control of water added to octopus (Octopus vulgaris and Eledone cirrhosa). O. vulgaris had significant higher values of moisture content, moisture/protein ratio, and cooking loss than E. cirrhosa. Immersion in freshwater increased the weight of O. vulgaris in ca. 32% after 32 h, and of E. cirrhosa in ca. 21% after 36 h, and cooking losses increased about 13.9% and 26.1%, respectively. The results reveal how consumers can be misled by abusive water addition. Changes in electrical conductivity and TDR curves were linked with the increasing incorporation of water and dilution effect of salts from octopus muscle. TDR technology and linear discriminant analysis were combined to detect added water in octopus. The classification model developed was cross-validated and 98.6% of samples were correctly classified. The method can be used to proof the authenticity of octopus (O. vulgaris and E. cirrhosa) or to detect fraudulent practices regarding added water. [ABSTRACT FROM AUTHOR]

Octopus vulgaris (Cuvier, 1797) is a cephalopod species with great economic value. In western Asturias (northwest of Spain), O. vulgaris artisanal fisheries are relatively well monitored and conditionally eco-labeled by the Marine Stewardship Council (MSC). Despite this, the Asturian octopus stocks have not been genetically assessed so far. In order to improve the current fishery plan and contrast the octopus eco-label validity in Asturias, 539 individuals from five regions of the O. vulgaris geographic distribution, including temporal samplings in Asturias, were collected and genotyped at thirteen microsatellite loci. All the samples under analysis were in agreement with Hardy–Weinberg expectations. Spatial levels of genetic differentiation were estimated using F-statistics, multidimensional scaling, and Bayesian analyses. Results suggested that the O. vulgaris consists of at least four genetically different stocks coming from two ancestral lineages. In addition, temporal analyses showed stability in terms of genetic variation and high NE (> 50) for several generations in different localities within Asturias, pointing out to indeed sustainable fishery exploitation levels. Even though, the current Asturias fishery plan shows no significant genetic damages to the stocks, the regional-specific management plans need systematic genetic monitoring schemes as part of an efficient and preventive regional fishery regulation strategy. [ABSTRACT FROM AUTHOR]

Octopus vulgaris type III preys upon molluscs by drilling a hole in the shell, through which it injects venom, weakening the muscles and allowing the octopus to remove and eat the mollusc flesh. In False Bay, South Africa, the abalone Haliotis midae, the kelp limpet Cymbula compressa and the helmet snail Semicassis zeylanica, are all common octopus prey, but each has a very different shell morphology and underlying anatomy. It is hypothesized that O. vulgaris type III targets the muscle attachment site of all three species and that the precision of drilling should correlate with the relative size of these muscle attachment sites. Measurements of the locations of drill holes from collected shells of each species showed that drilling locations were significantly non-random. In the abalone and limpet, the muscle attachment site was targeted two and 4.5 times more frequently than expected, respectively. Octopus vulgaris type III drilled helmet snails with extreme precision, with over half the holes drilled on the spire at an angle of 45° and 90° from the lip. Kernel density heat maps demonstrated that octopus drilled abalone with low precision, limpets with medium precision and helmet snails with high precision. The reason for the high precision in the helmet snail remains speculative, as the main drilling location did not align with the columellar muscle attachment and no target could be defined. This study is the first to assess octopus drilling in temperate southern Africa and to compare drilling precision across different prey species. [ABSTRACT FROM AUTHOR]