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A new Octopus Cuvier, 1797 species, Octopus djinda Amor, 2021 (previously treated as O. cf. tetricus and O. aff. tetricus), is described from the shallow waters off southwest Australia. This species was classified as conspecific with O. tetricus Gould, 1852 from Australia’s east coast and New Zealand but is shown here to be morphologically and genetically distinct. This description is based on 25 individuals across three localities in southwest Australia, encompassing most of its distribution. Greater and non-overlapping sucker counts on the males hectocotylised arm delimit east and west coast forms. DNA barcoding using cytochrome c oxidase subunit I also successfully differentiates between these taxa; 13 polymorphisms along a 349 bp partial fragment (3.7% sequence divergence). A close relative of the O. vulgaris Cuvier, 1797 species-group, O. djinda, sp. nov. supports a highly productive fishery and is currently one of two octopod fisheries worldwide to have received sustainable certification from the Marine Stewardship Council. The taxonomic description presented here provides formal recognition of the taxonomic status of southwest Australia’s common octopus, O. djinda, sp. nov. and facilitates appropriate fisheries catch reporting and management.

[ES] This study highlights for the first time individual differences in ethology and vulnerability of Octopus vulgaris (i.e. body postures, movements and skin displays) facing passive baited traps. Common octopus exposed to a baited trap during three consecutive first-capture tests exhibited diverse behavioural and body pattern sequences resembling when the octopus searches for and hunts its wild prey. Overall, they first visually recognized new objects or potential preys and rapidly moved out of the den, exploring, grabbing and approaching the trap with the arms (chemotactile exploration), and capturing the bait with the arms and feeding on top over long periods inside the trap. Simultaneously, O. vulgaris displayed diverse skin textural and chromatic signs, the regular pattern being the most frequent and long-lasting, followed by broad mottle, passing cloud and dark patterns. All individuals (n=8) caught the bait at least once, although only five octopuses (62.5%) entered the trap in all three tests. In addition, high variability among individuals was observed regarding behaviour and body patterns during the first-capture tests, which might evidence different individual temperaments or life-history traits. Differences in behavioural responses at individual level might have population consequences due to fisheries-induced selection, although there is a high necessity to assess how behavioural traits might play an important role in life-history traits of this species harvested by small-scale trap fisheries., [ES] Este estudio muestra por primera vez las diferencias individuales en cuanto al comportamiento y la vulnerabili-dad del pulpo Octopus vulgaris (posturas corporales, movimientos, patrones de piel) frente a las trampas con cebo (nasas). Los pulpos fueron expuestos a una trampa con cebo durante tres pruebas consecutivas para estudiar la primera captura, y exhibieron secuencias comportamentales y patrones corporales que se asemejan a cuando el pulpo busca y caza sus presas en el medio natural. En general, primero reconocen visualmente nuevos objetos o potenciales presas, y rápidamente salen de su refugio, explorando el entorno y acercándose a la trampa, agarrando con los brazos (exploración quimiotáctil), y capturando el cebo con los brazos y alimentándose durante largos períodos dentro de la trampa. Simultáneamente, O. vul-garis mostró diversos patrones cromáticos y de textura de la piel, siendo el patrón “regular” el más frecuente y duradero, seguido de amplios patrones moteados, dinámicos y oscuros. Todos los individuos (n=8) capturaron el cebo al menos una vez, aunque sólo cinco pulpos (62.5%) entraron en la trampa en las tres pruebas. Además, se observó una gran variabilidad entre los individuos en cuanto al comportamiento y los patrones corporales durante las pruebas de primera captura, lo que podría evidenciar diferentes temperamentos individuales o rasgos de la historia de la vida. Las diferencias en las respues-tas conductuales a nivel individual podrían tener consecuencias para la población debido a una selección inducida por la pesca, aunque es necesario evaluar cómo los rasgos conductuales podrían desempeñar un papel importante en el ciclo vital de esta especie, capturada por pescadores artesanales con trampas o nasas., This work is a contribution of the Joint Associated Unit IMEDEA-LIMIA. G.F-B. was supported by a Spanish PhD fellowship (FPI-INIA) from the National Institute for Agricultural and Food Research and Tech-nology (INIA). P.A.L. was supported by a post-doc-toral grant (Juan de la Cierva–Incorporación; IJCI-2015-25595) from the Spanish Ministry of Economy, Industry and Competitiveness.

Cephalopods are important economic shellfish that have been developed extensively in the coastal water of various countries. Octopus vulgaris is a large-scaled economic cephalopod that is mainly cultured in South China. This study explored the effect of different diets on the volatile flavor and nutritional ingredients of O. vulgaris. Four diets were tested in four groups: Group A (fish (Scomberomorus niphonius)), Group B (crab (Helice tridens tientsinensis Rathbun)), Group C (clam (Mactra veneriformis)), and Group D (squid (Loligo japonica)). Octopus muscles were sampled after 36 days of feeding, and volatile flavor substances (VFSs), fatty acids (FAs), and amino acids (AAs) were detected. Results showed that the VFSs, FAs, and AAs of octopus in the four groups were obviously different. The sum of volatile ketones and aldehydes was higher in Group B than in the other groups, which could present much more flavors. All groups were abundant in unsaturated FAs, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). In terms of content and variety, the FAs in Group B were more beneficial to human health than those in the other groups. The content of each AA in Group B was basically higher than those in the other groups and was significantly higher than that in Group D (P < 0.05). Comparing the VFSs, FAs, and AAs in samples fed with four kinds of diets, the results indicate that using crab to feed O. vulgaris can achieve better effects on volatile flavor and nutritional ingredients.

Purpose Review octopus ocular anatomy and describe the histopathologic findings in three octopuses diagnosed with phakitis and retinitis. Animals Two common octopuses (Octopus vulgaris) and one giant Pacific octopus (Enteroctopus dofleini) with a history of ophthalmic disease. Methods A literature search was performed for the ocular anatomy section. Both eyes from all three octopuses, and two control eyes, were submitted for histopathologic evaluation. Hematoxylin and eosin stain was used for standard histopathologic evaluation; GMS stain was used to screen for fungi, gram stain for bacteria; and Fite's acid fast stain for acid fast bacteria. Results Anatomically, the anterior chamber of the octopus has direct contact with ambient water due to an opening in the dorsal aspect of a pseudocornea. The octopus lens is divided into anterior and posterior segments. The anterior half is exposed to the environment through the opening into the anterior chamber. Neither part of the lens has a lens capsule. The retina is everted, unlike the inverted vertebrate retina, and consists of just two layers. Histopathology revealed inflammatory phakitis and retinitis of varying severity in all six eyes of the study animals. No intraocular infectious organisms were recognized but one common octopus eye had clusters of coccidian parasites, identified as Aggregata sp., in extraocular tissues and blood vessels. Conclusion We describe inflammatory phakitis and retinitis in two species of octopuses. The underlying cause for the severe intraocular response may be direct intraocular infection, water quality, an ocular manifestation of a systemic disease, or natural senescence.

A common feeding association among reef fishes involves nuclear and follower species, where the former disturbs the bottom, during which the latter opportunistically feeds on items exposed. Here, we report such interactions between Western Australian common octopuses (Octopus (cf) tetricus) and brown-spotted wrasse (Notolabrus parilus) observed on eight occasions while snorkeling at four temperate-water reefs along the coast of Perth in Western Australia. We compare the interactions observed to other octopus-fish nuclear–follower associations known. In general, these interactions usually benefit the follower species and could play a significant role on reef trophodynamics.

The complete mitochondrial genome of the East Asian common octopus (Octopus sinensis) was determined and analyzed in this work. The circular mitogenome of O. sinensis is 15,737 bp in length with 21.53% GC content, which contains two ribosomal RNA genes (rRNAs), 22 transfer RNA genes (tRNAs), 13 protein-coding genes (PCGs) and a non-coding region (D-loop). The analysis of the SNPs revealed 4 conservative SNPs for COI gene of O. sinensis compared with Octopus vulgaris. Phylogenetic analysis suggested that O. sinensis is closely related to O. vulgaris. This sequence data would play an important role in the investigation of phylogenetic relationship and taxonomy of the class Cephalopoda.

The reproductive performance of Octopus vulgaris broodstocks fed two different diets (mixed fish [F group, BW 1,048.14 g] or mixed crustaceans [C group, BW 998.44 g]) was analyzed using an experimental recirculating aquaculture system consisting of a tank equipped with spawning and incubation chambers. A total of 8 females (F1–4; C1–4), and 8 males (M1–M8) were selected. DI of the C group females was significantly (p

17 pages, 4 tables, 8 figures, The common octopus Octopus vulgaris Cuvier, 1797, once considered a cosmopolitan species, is a species complex composed by six species: O. tetricus, O. cf tetricus and O. sinensis in the Pacific; type I and II, in the West Atlantic; and type III in the Indian Ocean around South Africa. The tropical western central Atlantic is an important octopus fishing ground targeting O. maya, O. insularis, and a cryptic species considered to be O. vulgaris type I. In order to clarify the identification of this octopod, phylogenetic analyses were carried out with mitochondrial (COI and 16S) and nuclear (rhodopsin) genes, together with morphological analyses of 16 specimens caught in the northeastern continental shelf of Yucatan (Mexico). The main morphological traits differing from O. vulgaris were the presence, position and size of enlarged suckers and hectocotylus sucker number in males. Genetic distances and haplotype networks of the species complex were estimated using 285 COI sequences of nine Octopus species from 14 different locations around the world. The octopod sequences from Yucatan clustered within a monophyletic group that included sequences of O. vulgaris type II for the three genes analyzed. Phylogenetic distances with other members of the complex ranged between 2.71 and 3.89% using COI data. These genetic results support the presence of Octopus americanus Monfort, 1802 (formerly known as O. vulgaris type II) along the Yucatan continental shelf, a new octopod extending from the north of Argentina to the northwest coast of the USA, The results of this study were obtained as part of the project “Distribution, reproduction, biomass and movement patterns of the Octopus vulgaris common octopus, Cuvier 1797, on the Yucatan coast” with funding from the National Council of Science and Technology of Mexico (CONACyT) (No. 237057). This work was partially supported by the Project CALECO (CTM2015-69519-R) funded by the Spanish Ministry of Economy and Competitiveness and FEDER Funds

The East Asian common octopus Octopus sinensis is a bottom-dwelling species, but goes through a planktonic phase as ‘paralarvae’ during the first several weeks of life. As the swimming performance of the paralarvae is relatively poor, their dispersion relies primarily on ocean currents; however, vertical swimming may play an important role in their horizontal dispersion by controlling their buoyancy in the current. Within this context, ontogenic changes in vertical swimming in relation to the ambient water flow are key to understanding the dispersion properties of the paralarvae and the subsequent onset of settlement, yet this information remains largely unknown. Here, we investigated the effects of different water flows (downward × 4 velocities, stagnant and upward × 5 velocities) on the vertical swimming position in test columns using laboratory-raised O. sinensis paralarvae aged 0, 5, 10 and 15 days during the day and at night. Paralarvae younger than 10 days ( 5 mg) commenced short clinging behaviour, and their swimming positions dispersed downwards during daytime regardless of the water flow, indicating the onset of the transition to settlement. In contrast, their position shifted to near the upper limit at night by swimming upwards, even under downward water flows. Our results suggest that O. sinensis exhibits characteristic behaviour that alternates between diurnal descent dispersion with clinging (hyperbenthic trait) and nocturnal upward swimming (planktonic trait) during the transition to permanent benthic life.

This study assessed the presence of 27 pharmaceutically active compounds belonging to common therapeutic groups (cardiovascular, antiashmatic, psychoactive, diuretic, analgesic/anti-inflammatory, and antibiotic drugs) in the tissues of representative seafood species of bivalves, cephalopods, arthropods, and fish of high economic importance and consumption rates in North-Western Spain. Four pharmaceutical compounds, out of the 27 analyzed, were detected in the collected samples. The benzodiazepine citalopram was detected in the tissues of common octopus (14.1 ng g−1 dry weight) and pod razor (9.4 ng g−1 dw). The anxiolytic venlafaxine was detected in the tissues of common cockle (2.9 ng g−1 dw). The veterinary antiparasitic ronidazole was found in pod razor (2.3 ng g−1 dw) and, finally, the psychoactive compound alprazolam was also measured in common octopus (0.3 ng g−1 dw). Hazard quotients were calculated to assess the hazard posed by the consumption of the sampled seafoods. Octopus and pod razor tissues containing citalopram and alprazolam exceeded our chosen hazard limits (HQ > 0.1) for toddlers who are high consumers of seafood (HQ values between 0.18 and 0.27). A battery of biochemical biomarkers of effects (acetylcholinesterase, glutathione S-transferase; catalase, glutathione peroxidase and glutathione reductase enzymes activities and reduced/oxidized glutathione and malondialdehyde levels) was applied to samples of the study species with the aim of characterizing their basal levels and evaluating their suitability as a tool in the monitoring chronic exposure to environmental contaminants such as those analyzed in this study. According to the measured biomarkers, pod razor and cockles have the potential to be good bioindicator species, based on the observed among-site differences detected on acetylcholinesterase, glutathione S-transferase, catalase, glutathione peroxidase activities; reduced/oxidized glutathione and malondialdehyde levels.

Few studies focused on behaviour adaptations of organisms to marine litter (ML) pollution in Mediterranean Sea. This research, investigates on some behavior traits of Octopus vulgaris, focusing on the interaction with ML during the artisanal fishing activities by the bottom traps in a small coastal area of the southern Tyrrhenian Sea. For the first time, this pilot study uses an integrated approach based on the Fishermen Ecological Knowledge as well as the analysis of ML found in the traps. First assessment of plastic ingestion in this species are also reported. Plastic and metal were the predominant ML categories observed into the bottom traps. A total of 62 plastics, mainly small microplastics and fibres shaped, were ingested. The ML finding in the bottom traps suggests an interesting behavior of the common octopus regarding its interaction with ML, in fact, it seems to bring ML inside its dens, as a collector.

Octopuses have evolved incredibly large and complex nervous systems that allow them to perform impressive behaviors, like plan ahead, navigate and solve puzzles. The nervous system of the common octopus (also known as Octopus vulgaris) contains over half a billion nerves cells called neurons, similar to the number found in small primates. Two thirds of these cells reside in the octopuses’ arms, while the rest make-up a central brain that sits between their eyes. Very little is known about how this central brain forms in the embryo, including where the cells originate and which molecular factors drive their maturation in to adult cells. To help answer these questions, Deryckere et al. studied the brain of Octopus vulgaris at different stages of early development using various cell staining and imaging techniques. The experiments identified an important pool of dividing cells which sit in an area outside the central brain called the ‘lateral lips’. In these cells, genes known to play a role in neural development in other animals are active, indicating that the cells had not reached their final, mature state. In contrast, the central brain did not seem to contain any of these immature cells at the point when it was growing the most. To investigate this further, Deryckere et al. used fluorescent markers to track the progeny of the dividing cells during development. This revealed that cells in the lateral lips take on a specific neuronal fate before migrating to their target region in the central brain. Newly matured neurons have also been shown to travel large distances in the embryos of vertebrates, suggesting that this mechanism may be a common strategy for building large, complex brains. Although the nervous system of the common octopus is comparable to mammals, they evolved from a very distant branch of the tree of life; indeed, their last common ancestor was a worm-like animal that lived about 600 million years ago. Studying the brain of the common octopus, as done here, could therefore provide new insights into how complex nervous systems, including our own, evolved over time.

Summary Octopods are masters of camouflage and solve complex tasks, and their cognitive ability is said to approach that of some small mammals. Despite intense interest and some research progress, much of our knowledge of octopus neuroanatomy and its links to behavior and ecology comes from one coastal species, the European common octopus, Octopus vulgaris. Octopod species are found in habitats including complex coral reefs and the relatively featureless mid-water. There they encounter different selection pressures, may be nocturnal or diurnal, and are mostly solitary or partially social. How these different ecologies and behavioral differences influence the octopus central nervous system (CNS) remains largely unknown. Here we present a phylogenetically informed comparison between diurnal and nocturnal coastal and a deep-sea species using brain imaging techniques. This study shows that characteristic neuroanatomical changes are linked to their habits and habitats. Enlargement and division of the optic lobe as well as structural foldings and complexity in the underlying CNS are linked to behavioral adaptation (diurnal versus nocturnal; social versus solitary) and ecological niche (reef versus deep sea), but phylogeny may play a part also. The difference between solitary and social life is mirrored within the brain including the formation of multiple compartments (gyri) in the vertical lobe, which is likened to the vertebrate cortex. These findings continue the case for convergence between cephalopod and vertebrate brain structure and function. Notably, within the current push toward comparisons of cognitive abilities, often with unashamed anthropomorphism at their root, these findings provide a firm grounding from which to work.

This study evaluated the effects of shelter pipes (PS), tube shelters (TS), and no shelter (NS) on the growth of juvenile common octopus (Octopus vulgaris). The grow-out was studied in situ by conducting a passive follow-up survey using integrated transponder tags. The growth and survival rates were evaluated in two experiments. Each experiment included two replicates. Both experiments ran for 60 days, for which each trial included 24 octopuses that were fed once a day a diet of frozen sardines (Sardinops melanostictus) and swimming crabs (Portunus trituberculatus), at 3–8% body weight. We investigated the relationship between the beak microstructure of the common octopus and possible stress events caused by culture conditions at 15 °C for 15 days. The nine juveniles were separated into three groups (NC: natural conditions, PS: culture conditions as a group, and TS: culture conditions with individuals kept separately) to analyze the amount of stress caused by rearing conditions. Stress marks were observed using a high-resolution stereo fluorescence microscope. In Experiment 1, the specific growth rates (SGRs) were 0.20 ± 0.15% per day in the PS group, 0.24 ± 0.10% per day in the TS group, and 0.68 ± 0.48% per day in the NS group. The survival rate was 62.5 ± 6.25%, 37.5 ± 18.75%, and 12.5% in the TS, PS, and NS groups, respectively. The experimental conditions of Experiment 2 were the same as those in Experiment 1, except that Experiment 2 involved different individuals and occurred during a different season. In Experiment 2, the SGRs were 0.54 ± 0.20% per day in the PS group, 0.59 ± 0.22% per day in the TS group, and 0.44 ± 0.10% per day in the NS group. Survival rate was 87.5 ± 6.25%, 75 ± 6.25%, and 75% in the TS, PS, and NS groups, respectively. Regression analysis showed that the water temperature (from 5.4–23.1 °C) affected the growth of octopuses in Experiments 1 and 2. Capture stress was detected in six of the nine individuals (NC, PS, and TS combined). Statistically significant differences in the stress levels were detected between the PS and TS groups (P ≤ 0.1), with the NC group exhibiting no stress lines after initial adaptation, unlike PS. In conclusion, octopuses kept in TS were not affected by stress after initial adaptation.

Despite recent advances in culture technology for East Asian common octopus Octopus sinensis paralarvae using upwelling systems, securing suitable feed for the paralarvae is an unresolved issue. The zoea of the swimming crab Portunus trituberculatus is a good candidate for paralarval feed because of the high fecundity of the adult females. To investigate the effects of supplying P. trituberculatus zoeae and their feeding method on paralarvae, we cultured paralarvae with supplying different combination ratios of zoeae and Artemia (10:0, 7:3, 5:5, 3:7 and 0:10), and with or without supplementing rotifers using small‐scale (3‐L) upwelling systems. Paralarval survival rate and growth were improved when zoeae were supplied as the main feed, but reduced when the proportion of Artemia exceeded half the whole preys. Supplementing rotifers did not affect the paralarval survival and growth. Subsequently, paralarvae were cultured by supplying zoeae (partially augmented by Artemia) using three large (1‐kl) upwelling systems to assess their feeding effectiveness in juvenile octopus production. Paralarvae could be cultured at high survival rates of 77.1 ± 5.1% to reach benthic juveniles at 23 days after hatching. In conclusion, supplying P. trituberculatus zoeae augmented with Artemia under an upwelling culture system has great potential for juvenile octopus production.

Stock overexploitation, bycatch, discards and gear impacts on the environment are outstanding issues for Mediterranean fisheries. The adoption of alternative fishing gears is an appealing solution to ensure a more sustainable exploitation of resources. We discuss the pros and cons of pots as alternative gears by reviewing their main designs, spatial distribution and target species in the Mediterranean basin. We assessed the technical factors affecting the catch efficiency of the different pot designs for four target species: spiny lobster, Palinurus elephas; Norway lobster, Nephrops norvegicus; common octopus, Octopus vulgaris and pandalid shrimps, Plesionika spp. We found that pot volume is important to catch Octopus; mesh size to catch Nephrops and Plesionika; entrance surface to catch Octopus, Nephrops and Plesionika; pot shape/colour and entrance shape/position to catch Octopus and Plesionika; and bait type to catch Octopus and Nephrops. The literature review shows that pot fisheries have several considerable advantages over conventional gears, especially in terms of discards, bycatch, seabed impacts (particularly compared with bottom trawls and passive set nets), size and species selectivity, gear depredation, catch quality and gear cost, besides saving time and labour. Disadvantages hampering their wider diffusion include ghost fishing, a low catch of finfish species, the narrow range of species targeted by each pot design and the current early stage of research. These data make a clear case for using pots as alternative gears to traditional ones in the Mediterranean Sea in some areas and seasons to catch certain target species.

14 pages, 6 figures, 4 table.-- This is an open access article distributed under the Creative Commons Attribution License, The common octopus (Octopus vulgaris) is a highly valued cephalopod species which is marketed with different grades of processing, such as frozen, cooked or even canned, and is likely to be mislabeled. Some molecular methods have been developed for the authentication of these products, but they are either labor-intensive and/or require specialized equipment and personnel. This work describes a newly designed rapid, sensitive and easy-to-use method for the detection of Octopus vulgaris in food products, based on Recombinase Polymerase Amplification (RPA) and a detection using a Lateral Flow assay (LFA). After studying several gene markers, a system of primers and nfo-probe was designed in the COI (Cytochrome Oxidase I) region and was successfully tested in 32 reference samples (covering 14 species) and 32 commercial products, after optimization. The method was also validated in a ring trial with eight European laboratories and represents a useful tool for food authenticity control at all levels of the value chain, This study is part of the SEATRACES project (www.seatraces.eu), funded by the EU Interreg Atlantic Area Programme (project number EAPA_87/2016)

A peptide with structural features similar to those of chordate GnRHs was originally isolated from the central nervous system of the Japanese common octopus, Octopus vulgaris. It was named oct-GnRH, and was the first GnRH-related peptide in mollusks. Oct-GnRH has also been characterized from the central nervous systems of the common cuttlefish Sepia officinalis, and the swordchip squid Uroteuthis edulis. Oct-GnRH induces gonadal maturation and oviposition by regulating sex steroidogenesis and a series of egg-laying behaviors, as a key peptide in the octopus analog of the hypothalamo-hypophysial-gonadal axis. The localization of oct-GnRH mRNA expression and immunoreactive fibers in the brain, and the distribution of the oct-GnRH receptor in the brain and the peripheral tissues, suggest that oct-GnRH acts as a multifunctional modulatory factor in higher brain functions such as feeding behavior, the touch and visual memory system, cardiac control, arm movement, postural regulation, and sensory and autonomic functions. Molluscan GnRHs including the octopus, sea hare, and yesso scallop increase the Ca2 +-level but not cAMP production via their receptors.

11 pages, 3 tables, 2 figures, The European Union (EU) is one of the most important markets for cephalopods in the world. Currently, small-scale fisheries targeting the common octopus in the EU are of considerable social and economic importance, especially in southern European waters where more octopus are consumed as part of the traditional diet. Octopuses in Europe are excluded from quota regulations under the Common Fisheries Policy and EU Member States manage their fisheries employing different input and output control measures, especially in small-scale fisheries targeting the common octopus. The level of participation of the fishing industry in the management of their activity varies amongst Member States and some management arrangements in place are tailored at the local level. This manuscript focuses on four European countries with important small-scale artisanal common octopus fisheries (Portugal, Spain, Italy and Greece). It describes and compares the current status of small-scale common octopus fisheries in each country, their socioeconomic importance, the management arrangements in place, and the opportunities and challenges for their future. Despite the increasing importance of octopus fisheries in southern Europe, few countries have collected detailed data on the socioeconomic importance and management of these fisheries. The information provided contributes to increase the knowledge about the human dimensions of octopus fisheries in Europe, This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. The print of figures in colour were financed by the INTERREG project CephsandChefs (EAPA 282/2016)

Octopods are masters of camouflage, solving complex tasks, expressing emotion and their cognitive ability is said to approach that of some small mammals. Despite intense interest and some research progress, much of our knowledge of octopus neuroanatomy and its links to behaviour and ecology comes from one coastal species, the European common octopus, Octopus vulgaris a largely nocturnal coastal dweller. Octopod species are found in habitats including complex coral reefs to the relatively featureless deep mid-water. There they encounter different selection pressures, may be nocturnal or diurnal and mostly solitary or partially social. How these different ecologies and behavioural differences influence the octopus central nervous system (CNS) or brain remains largely unknown. Here we present a phylogenetically-informed comparison between diurnal and nocturnal coastal and a deep-sea species using brain imaging techniques. This study shows that characteristic neuroanatomical changes are linked to their life modes and ecological niches. Octopods are voracious visual predators and we demonstrate enlargement and division of the optic lobe as well as structural foldings and complexity in the underlying CNS. It appears these modifications are linked to behavioural adaptation (diurnal versus nocturnal; social versus solitary) and ecological niche (reef versus deep sea), but phylogeny may play a part also. The difference between solitary and social life is mirrored within the brain including the formation of multiple compartments, or gyri, in the vertical lobe. This brain region has previously been linked to cognitive capability and is likened to the vertebrate cortex. Some of the life-mode related modifications described here are convergent with similar progressions of complexity found within the vertebrates. These findings continue the case for convergence between cephalopod and vertebrate brain structure and function. Notably, within the current push towards comparisons of cognitive abilities, often with unashamed anthropomorphism at their root, these findings provide a firm grounding from which to work.

Recent research hypothesised that the Siculo-Tunisian Strait might fit, at least for some species, the picture of a genetic transitional zone instead of a sharp genetic break between the Western and Eastern Mediterranean basins. The present study aimed at using the common Octopus, Octopus vulgaris as an empirical test-case to evaluate this hypothesis. To accomplish this goal, 458 new sequences of the mitochondrial gene cytochrome c oxidase subunit I were used. Combining the new sequences with those available on public databases, we assembled a dataset containing 920 sequences to investigate the spatial genetic patterns across 34 Mediterranean populations of O. vulgaris. The genetic structure of this species was assessed combining analysis of molecular variance and Median-Joining networks. Results supported the hypothesis of a complex spatial genetic pattern across the Sicilian channel. Contemporary factors, such as marine currents, likely affect the species’ genetic structuring across this area. Overall, our results highlighted that focusing the attention on the whole transitional area rather than on a unique genetic break might help to detect similar patterns across different species. Finally, acknowledging the occurrence of complex spatial genetic patterns across transitional zones may improve stock identification and management practices for commercially valuable species.

BACKGROUND Dicyemids are parasites found in the renal sac of cephalopods. The first species of dicyemid was found from kidneys of the Korean common octopus Callistoctopus minor. OBJECTIVES This study aimed to identify the dicyemid and investigate the effect on renal sac of host. METHODS In this study, we compared the morphological characteristics of isolate to dicyemids (Dicyema sphyrocephalum, Dicyema clavatum, and Dicyema dolichocephalum) reported from C. minor in Japan. We compared the 18S ribosomal RNA (rDNA) and cytochrome c oxidase subunit I (COI) sequences of isolate to the sequences of D. shyrocephalum and D. clavatum. The infected octopuses renal tissues were histologically compared with the tissues of uninfected individuals. RESULTS The morphological characteristic of this isolated species corresponds to D. sphyrocephalum. The sequences similarities of 18S rDNA and COI gene of isolate are 99.7% and 98.1% with D. sphyrocephalum. We observed morphological changes in the epithelia folds of kidney at the dicyemids attached areas. CONCLUSIONS The present study identified the isolate as D. sphyrocephalum and this is the first report of dicyemid species from Republic of Korea. Further studies on the effects of dicyemids on growth and health status of cephalopods will be needed.

Artemia are potential food organisms for the mass culture of common octopus paralarvae but cause poor paralarval growth and mortality. To understand problems arising from Artemia use, we focused on Artemia flocculation in paralarval culture tanks; Artemia get caught up with each other, exhibit disrupted swimming, are deposited on the tank bottom and eventually die. To clarify whether paralarvae induce the flocculation of food organisms or not, we cultured newly hatched Artemia nauplii, 3-day-old metanauplii and decapod crustacean zoeae with or without paralarvae at different growth stages (weight). Flocculation occurred only when Artemia were cultured with paralarvae; metanauplii had a higher susceptibility for flocculation than nauplii. Flocculated Artemia proportion increased with increasing paralarval weight. Scanning electron microscopy revealed that flocculated metanauplii had deformed setules on their setae, with hook-shaped tips and adhesion of neighbouring tips, suggesting that flocculation may occur via a mechanism similar to the ‘hook-and-loop fastener’. As octopus paralarvae exhibit external digestion, digestive enzymes secreted by paralarvae may deform Artemia setules and result in flocculation. As flocculation did not occur when metanauplii were cultured in water in which paralarvae were cultured and then removed, causative enzymes were probably rapidly inactivated after secretion.

Background: Octopus vulgaris has been an iconic cephalopod species for neurobiology research as well as for cephalopod aquaculture. It is one of the most intelligent and well-studied invertebrates, possessing both long- and short-term memory and the striking ability to perform complex cognitive tasks. Nevertheless, how the common octopus developed these uncommon features remains enigmatic. O. vulgaris females spawn thousands of small eggs and remain with their clutch during their entire development, cleaning, venting and protecting the eggs. In fact, eggs incubated without females usually do not develop normally, mainly due to biological contamination (fungi, bacteria, etc.). This high level of parental care might have hampered laboratory research on the embryonic development of this intriguing cephalopod. Results: Here, we present a completely parameter-controlled artificial seawater standalone egg incubation system that replaces maternal care and allows successful embryonic development of a small-egged octopus species until hatching in a laboratory environment. We also provide a practical and detailed staging atlas based on bright-field and light sheet fluorescence microscopy imaging for precise monitoring of embryonic development. The atlas has a comparative section to benchmark stages to the different scales published by Naef (1928), Arnold (1965) and Boletzky (2016). Finally, we provide methods to monitor health and wellbeing of embryos during organogenesis. Conclusion: Besides introducing the study of O. vulgaris embryonic development to a wider community, this work can be a high-quality reference for comparative evolutionary developmental biology., Sí

Octopus vulgaris, well-known from temperate waters of the Mediterranean Sea and a well-cited model species among the cephalopods, has large eyes with which it scans its environment actively and which allow the organism to discriminate objects easily. On cursory examination, the single-chambered eyes of octopus with their spherical lenses resemble vertebrate eyes. However there are also apparent differences. For example, the retina of the octopus is everted instead of inverted, and it is equipped with primary rhabdomeric photoreceptors rather than secondary ciliary variety found in the retina of the vertebrate eye. The eyes of octopus are well adapted to the habitat and lifestyle of the species; the pupil closes quickly as a response to sudden light stimuli mimicking a situation in which the octopus leaves its den in shallow water during daytime. Although the many general anatomical and physiological features of octopus vision have been described elsewhere, our review reveals that a lot of information is still missing. Investigations that remain to be undertaken include a detailed examination of the dioptric apparatus or the visual functions such as brightness discrimination as well as a conclusive test for a faculty analogous to, or in lieu of, color vision. For a better understanding of the octopus eye and the functions mediated by it, we suggest that future studies focus on knowledge gaps that we outline in the present review.

21 pages, 11 figures.-- This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY), The common octopus, Octopus vulgaris, has a short life cycle, growing rapidly to maturity, spawning once, and characterized by an asynchronic oocyte development and a synchronic ovulation dying after breeding. This species has a protein and amino acid metabolism and it is usually defined as an income breeder. However, most biochemical studies lack an examination of the whole reproductive cycle, in particular the spawning process. We here studied the biochemical changes and determined the energy strategy along reproduction in female O. vulgaris, and found that proteins were the main energy reserve, primarily located in the body muscle when sexually maturing and decreasing during breeding. Lipids were also an important source of energy in the ovary and digestive gland and decreased during breeding too. By contrast, glycogen had a minor contribution to the energy content and was the unique compound that increased in spawning and post-spawning females. Additionally, the most abundant fatty acids (FA) in all tissues were 16:0, 18:0, 20:1n9, 20:4n6 (ARA), 20:5n3 (EPA) and 22:6n3 (DHA), with a clear predominance of long-chain polyunsaturated FA. The FA profile of mature ovaries was compared with other life stages finding similitudes with eggs, hatchlings and juveniles but considerable differences with paralarvae which showed higher DHA/ARA and EPA/ARA ratios. Therefore, we found important biochemical changes along the reproductive cycle that determined the energetic signature in each tissue, though no significant energy trade-offs between tissues were found, suggesting that, on the one hand, female O. vulgaris obtained energy directly from food accumulated simultaneously in the somatic and reproductive tissues during sexual maturation. However, an energy reallocation from somatic to reproductive growth would occur once vitellogenesis has started, so that the rate at which body growths would decrease in favor of ovary growth. On the other hand, during breeding, a general decrease in the energy content occurred in all tissues, so that the ovary would be responsible for the spawning success, whereas muscle tissues and digestive gland would independently supply the energy needed for the body maintenance safeguarding the female survival needed for the maternal care, This work was funded by the Comisión Interministerial de Ciencia y Tecnología (CICYT, Spain) (Project VEM 2003–20010) and by Xunta de Galicia (PGIDIT04PXIC40207PN). PS was supported by a doctoral grant of Universidade de Vigo and a fellowship of Departamento de Postgrado y Especialización (CSIC)

This study aimed at selecting effective histological indicators of the freezing process, for the discrimination of fresh and frozen common octopus Octopus vulgaris. Histological indices of freezing process were selected in mantle and arm muscle and axial nerve tissues. Seven histological parameters were chosen: overall muscle tissue structural organization (a); gaping among muscle bundles (b); presence of optically empty spaces between and within muscle bundles (c); white spaces percentage between and within muscle bundles (d); overall nerve structural organization (e); presence of linear fissures and/or empty spaces within neuropil and axonal tract (f); presence of empty spaces within connective tissue matrix surrounding the nerve (g); empty space percentage within arm axial nerve region (h). The parameters were assessed on 150 mantle muscle sections (a, b, c, d), 150 arm muscle (b, c) and nervous (e, f, g, h) tissue sections belonging to 20 fresh exemplars further subdued to conventional freezing procedure at − 20 °C, 25 fresh curled exemplars, 25 exemplars industrially frozen at − 80 °C, and 20 thawed, curled, and individually quick frozen exemplars. Overall structural organization (a, e), gaping (b), and presence of optically empty spaces (c, f) confirmed significant morphological freezing indices in mantle and arm sections. In mantle, two d values (d

10 pages, 5 figures, 1 table, The common octopus (Octopus vulgaris) is a species of great interest to the aquaculture industry. However, the high mortalities registered during different phases of the octopus lifecycle, particularly the paralarvae stage, present a challenge for commercial aquaculture. Improvement of diet formulation is seen as one way to reduce mortality and improve growth. Molecular growth-markers could help to improve rearing protocols and increase survival and growth performance; therefore, over a hundred orthologous genes related to protein balance and muscle growth in vertebrates were identified for the common octopus and their suitability as molecular markers for growth in octopus paralarvae explored. We successfully amplified 14 of those genes and studied their transcription in paralarvae either fed with artemia, artemia + zoea diets or submitted to a short fasting-refeeding procedure. Paralarvae fed with artemia + zoea had higher growth rates compared to those fed only with artemia, as well as a significant increase in octopus mtor (mtor-L) and hsp90 (hsp90-L) transcription, with both genes also up-regulated during refeeding. Our results suggest that at least mtor-L and hsp90-L are likely linked to somatic growth in octopus paralarvae. Conversely, ckip1-L, crk-L, src-L and srf-L had expression patterns that did not match to periods of growth as would be expected based on similar studies in vertebrates, indicating that further research is needed to understand their function during growth and in a muscle specific context, This work has been carried out with financial support from the European Union under grant project AQUAEXCEL2020 (652831, TNA AE050063- Octogrowth) to DGS and MP. DGS is a Serra Húnter Fellow at the University of Barcelona. JHU is supported by a Juan de la Cierva’s post-doc research grant (# FJCI-2016-30990) funded by the Spanish Ministry of Science, Innovation and Universities

Despite a growing interest in common octopus for aquaculture, massive mortalities during the planktonic paralarval stage still hamper production. Prior to die-off during rearing trials for paralarvae, it could be observed that the food-capturing paralarvae tended to be carried downward in a current induced by the aeration system, eventually depositing the animals on the tank bottom. The aim of this study was to investigate the effect of upwelling water-flow, that might support paralarval swimming and floating, on paralarval survival and growth. A new artificial upwelling rearing system using a strong downward flow in the center to the bottom of the tank was developed. The effects of the new system in combination with supplying natural zooplankton (mainly decapod crustacean zoeae) or Artemia were evaluated using three different broods hatched from three mothers (broods A, B, and C). As food items for zooplankton, n-3 highly unsaturated fatty acid (n-3 HUFA)-fortified rotifers and digestible microalgae Nannochloropsis oculata were supplemented. The hatchling dry weight was significantly different among broods, showing heavier weight in order of broods A > C > B. Use of the upwelling rearing system significantly improved the rate of paralarval survival as compared with using the standard system, and paralarval growth was significantly faster when reared in the upwelling system with zooplankton supplementation. Paralarvae in the upwelling + zooplankton group kept high survival rates over 80% until 18 days after hatching (DAH). The survival rate of the tank of brood A could achieve 80.8% at 20 DAH, however, those of broods B and C dropped to 8.2% and 54.4% at 20 DAH, respectively, presumably due to combined effect of small hatchling size and insufficient food supply. The octopuses of broods A and C reached benthic stage by 25 and 23 DAH, with survival rates of 51.0% and 45.3%, respectively. The overall results suggest that an inadequate water-flow environment in combination with poor food quality and quantity are major causes of paralarval mortality of the common octopus. For culturing paralarvae, the combined use of an upwelling rearing system and supplying decapod crustacean zoeae supplemented with n-3 HUFA fortified rotifers and digestible N. oculata was recommended.

11 pages, 3 figures, The salivary apparatus of the common octopus (Octopus vulgaris) has been the subject of biochemical study for over a century. A combination of bioassays, behavioral studies and molecular analysis on O. vulgaris and related species suggests that its proteome should contain a mixture of highly potent neurotoxins and degradative proteins. However, a lack of genomic and transcriptomic data has meant that the amino acid sequences of these proteins remain almost entirely unknown. To address this, we assembled the posterior salivary gland transcriptome of O. vulgaris and combined it with high resolution mass spectrometry data from the posterior and anterior salivary glands of two adults, the posterior salivary glands of six paralarvae and the saliva from a single adult. We identified a total of 2810 protein groups from across this range of salivary tissues and age classes, including 84 with homology to known venom protein families. Additionally, we found 21 short secreted cysteine rich protein groups of which 12 were specific to cephalopods. By combining protein expression data with phylogenetic analysis we demonstrate that serine proteases expanded dramatically within the cephalopod lineage and that cephalopod specific proteins are strongly associated with the salivary apparatus, This study was funded by a La Trobe University Understanding Disease Research Focus Area small project grant

This study aimed to develop a method of administering F-18-FDG to the common octopus in order to perform a PET biodistribution assay characterizing glucose metabolism in organs and regenerating tissues. Methods: Seven animals (two of which had a regenerating arm) were anesthetized with 3.7% MgCl2 in artificial seawater and then injected with 18-30 MBq of isosmotic F-18-FDG through either the left branchial heart or the anterior vena cava. After an uptake time of about 50 min, the animals were sacrificed and placed on the bed of a small-animal PET scanner, and 10-min static acquisitions were obtained at 3-4 bed positions to visualize the entire body. To confirm image interpretation, internal organs of interest were collected and counted with a.-counter. Results: Administration through the anterior vena cava resulted in a good full-body distribution of F-18-FDG as seen on the PET images. Uptake was high in the mantle mass and relatively lower in the arms. In particular, the brain, optic lobes, and arms were clearly identified and were measured for their uptake (SUVmax: 6.57 +/- 1.86, 7.59 +/- 1.66, and 1.12 +/- 0.06, respectively). Interestingly, F-18-FDG uptake was up to 3-fold higher in the highly proliferating areas of regenerating arms. Conclusion: This study represents a stepping-stone to the use of non-invasive functional techniques for addressing questions about invertebrate neuroscience and regenerative medicine.

The common octopus (Octopus vulgaris) has aroused great interest in recent years as a new species for aquaculture. The current research is focused on developing a formulated feed, although a proper diet management has also promoted rearing success of other commercial cultured species. It is documented that wild animals eat depending on prey availability and most experience fasting in nature. Hence, O. vulgaris subadults were subjected to two different feeding schemes, with a similar semi-moist diet, including either 2 (2FDb, control) or 3 (3FDb) non-consecutive days of fasting per week. Growth, feed efficiency (FE), digestibility and condition were assessed after 56 days of rearing. Both feeding schemes promoted similar growth and digestibility (P>0.05), 100% of survival and higher food-intake after fasting. Interestingly, feed efficiency (FE) was enhanced with the 3 fasting days scheme (58.6% vs. 48.3% for 2FDb scheme; P

Domoic acid (DA) is a neurotoxin that causes degenerative damage to brain cells and induces permanent short-term memory loss in mammals. In cephalopod mollusks, although DA is known to accumulate primarily in the digestive gland, there is no knowledge whether DA reaches their central nervous system. Here we report, for the first time, the presence of DA in brain tissue of the common octopus (Octopus vulgaris) and the European cuttlefish (Sepia officinalis), and its absence in the brains of several squid species (Loligo vulgaris, L. forbesi and Todarodes sagittatus). We argue that such species-specific differences are related to their different life strategies (benthic/nektobenthic vs pelagic) and feeding ecologies, as squids mainly feed on pelagic fish, which are less prone to accumulate phycotoxins. Additionally, the temporal persistence of DA in octopus’ brain reinforces the notion that these invertebrates can selectively retain this phycotoxin. This study shows that two highly-developed invertebrate species, with a complex central nervous system, where glutamatergic transmission is involved in vertebrate-like long-term potentiation (LTP), have the ability of retaining and possibly tolerating chronic exposure to DA, a potent neurotoxin usually acting at AMPA/kainate-like receptors. Here, we filled a gap of information on whether cephalopods accumulated this neurotoxin in brain tissue, however, further studies are needed to determine if these organisms are neurally or behaviourally impaired by DA.

During a Scuba survey in Iskenderun Bay at night time on November 2018, a female Urocaridella pulchella individual was observed with nocturnal cleaning on Octopus vulgaris at 16 m in depth. Some photos of the shrimp and its symbiont were taken. Although the nocturnal cleaning relationship between U. pulchella and various marine species has been reported in some studies, the nocturnal cleaning relationship between O. vulgaris and U. pulchella has been observed for the first time. In addition, in the present study, we first reported Indo-Pacific palaemonid shrimp U. pulchella which was encountered in its natural habitat during an underwater observation from Iskenderun Bay, and this report is the first observation for this area and fills a gap in the distribution range of this species. Keywords: eastern Mediterranean, Iskenderun coast, nocturnal cleaning, Palaemonidae, Turkey.

Settlement is the process whereby benthic octopuses with a planktonic paralarval phase make a behavioural change from being active swimmers to assume adult life on the seabed . This process is poorly understood, mainly because octopus juveniles are highly cryptic in the natural habitat and they lack any distinct morphological changes (i.e. metamorphosis) in concert with settlement. To investigate behaviour during the settlement process, ontogenetic changes in swimming, clinging and shelter-utilizing behaviours were examined during both day- and night-time using laboratory-raised East Asian common octopus, Octopus sinensis, aged from 10 to 28 days after hatching (ranging from 1.7 to 16.4 mg mean dry weight, DW). The accompanying change in feeding habit from planktivorous to benthivorous was assessed by comparing rates of consumption of planktonic zoea (of the swimming crab Portunus trituberculatus ) and benthic juveniles of the Manila clam , Ruditapes philippinarum . During the daytime, octopus behaviour changed rapidly from swimming to clinging onto the surface of the wall and bottom of the test tank during growth from 3 to 9 mg DW. At night, the frequency of clinging behaviour increased along with growth but the behavioural change progressed more slowly, indicating a tendency to continue swimming during darkness. Shelter utilization during the day commenced mainly after reaching 8 mg DW, after which shelter use gradually increased with growth. In contrast, shelter utilization at night was rarely observed throughout the experiment. Regarding octopus prey preference , consumption of clam juveniles increased with growth while zoeae consumption remained constant. The increase in clam consumption, however, was gradual, indicating that the shift of feeding habit from planktivorous to benthivorous is by no means an abrupt transition. These results indicate that O. sinensis requires a considerable period of time to complete the transition to benthic life. The alternating behaviours of diurnal clinging and nocturnal swimming in the water column may facilitate safe migration of the octopuses from the location to which they have been passively advected towards a more suitable benthic habitat while minimizing their exposure to visual predators. Since shelter utilization and feeding on bivalves are likely to require the use of a certain degree of force and complex coordination of the arms and suckers, the extended, gradual increase in shelter utilization frequency and clam consumption may be attributable to the degree of arm and sucker development.

Genetic information is crucial for the proper exploitation of Octopus vulgaris, the most commercially valuable octopus species worldwide. The main aim of the present study was to investigate genetic structure, with the intent to inform effective management of the common octopus in Sardinia (western Mediterranean Sea), one of the most productive areas within Italian waters. Patterns of population structure were assessed in 246 specimens from seven population samples. Variation in five nuclear-encoded microsatellites and sequences of two mitochondrial genes (COI and COIII) highlighted high variability and low but significant genetic differentiation among populations, which clustered into four groups corresponding to the north, northwest, south, and east coasts of Sardinia. Secondarily, the sequence data from Sardinia were compared with GenBank data from other areas. AMOVA and Bayesian analyses supported the occurrence of significant differences within the Mediterranean Sea, and between Eastern Atlantic and Mediterranean samples. The described genetic differentiation at a regional geographical scale could be determined by a combination of historical and/or current events restricting gene flow. The occurrence of significant genetic structuring at different spatial scales is an important piece of information to define the most appropriate conservation strategies in the area, both at the local and regional level.

Adult common octopus individuals were intramuscularly infected with Photobacterium damsela subsp. piscicida in order to investigate if this species is sensitive to this common and important fish pathogen. The fate of the bacterial antigens and the tissue responses of Octopus vulgaris were studied employing immunohistochemical techniques. Strong reaction at the site of injection was evident from day 2 post-infection that continued until day 14. Great numbers of hemocytes that were attracted at the site of infection were involved in phagocytosis of bacteria. Very early in the infection, a transition of cells to fibroblasts and an effort to isolate the infection was observed. During the course of the study, very large necrotic cells were seen at the site of infection, whereas during the later stages hemocytes with phagocytosed bacteria were observed in well-defined pockets inside the muscle tissue. None of the internal organs tested for the presence of the bacterium were positive with the exception of the digestive gland where antigen staining was observed which was not associated with hemocyte infiltration. The high doses of bacterial cells used in this experimental infection and the lack of disease signs from Octopus vulgaris suggest that, under normal conditions, octopus is resistant to Photobacterium damsela subsp. piscicida.

Co-management has shown promising results for the sustainable use of fishery resources. The common octopus (Octopus vulgaris) pot and trap fishery in the Algarve (Portugal) holds the potential for implementation of a co-management system. To explore this potential, seven participatory workshops took place between 2014-2015, bringing together 60 participants from 10 fishing associations and 16 fisheries management and research institutions. The exercise resulted in promising outcomes with regards to the possible implementation of a co-management system for the fishery. In the present work an overview of the outcomes of the participatory workshops is given and compared with initiatives worldwide. Among the management actions identified, some have direct impacts on the octopus' life cycle, while all target the same overall objective: to regulate fishing effort. In the informal setting of the workshops, a formal request was developed: the establishment of an annual closed season in the Algarve. This request was taken into consideration by the responsible management institution. Portuguese Science Foundation (FCT) [SFRH/BD/51274/2010] FCT/MEC national funds FEDER [UID/AMB/50017/2013] info:eu-repo/semantics/publishedVersion

Behavioral asymmetries exhibited by the common octopus, Octopus vulgaris, a cephalopod mollusk, during predatory and exploratory responses were investigated. Animals were tested for eye preferences while attacking a natural (live crab) or an artificial (plastic ball) stimulus, and for side preferences while exploring a T-maze in the absence of any specific intra- or extra-maze cues. We found individual-level asymmetry in some animals when faced with either natural or artificial stimuli, but not when exploring the maze. Our findings suggest that visual lateralization in O. vulgaris is context-dependent.

Industrial cooking of common octopus (Octopus vulgaris) under well-established procedures is advantageous for current consumers, which demand healthy and convenient food. This work aimed to evaluate the effect of industrial water boiling, without the addition of salt, on the nutritional profile of common octopus. True retentions (TRs) were calculated for essential nutrients and toxic elements. After boiling, the moisture content decreased, resulting in a concentration of other constituents (protein, fat, fatty acids, majority of amino acids, phosphorus, zinc, and iodine). High TRs were obtained for some essential nutrients: 90.2% (eicosapentaenoic acid, EPA), 89.1% (docosahexaenoic acid, DHA), &ge, 74.6% (indispensable amino acids, IAA), and 86.8% (iodine). In both raw and boiled octopus, polyunsaturated fatty acids (252.2 and 425.1 mg/100 g), leucine (940.1 and 1613.4 mg/100 g), glutamate (1971.5 and 3257.1 mg/100 g), sodium (393.3 and 332.5 mg/100 g), and zinc (12.6 and 16.6 mg/kg) were, respectively, the most abundant fatty acids, IAA, dispensable amino acids, macro, and micro elements. Cadmium, lead, and mercury levels found in boiled octopus were 0.02, 0.10, and 0.08 mg/kg, respectively. The consumption of 150 g (usual portion) of boiled octopus is advisable because it contributes to significant daily intakes of EPA+DHA (&gt, 100%), selenium (75.6%), and iodine (12.4%), and 25% of the daily adequate intake of sodium for adults.

Spontaneous nerve regeneration in cephalopod molluscs occurs in a relative short time after injury, achieving functional recovery of the lost capacities. In particular, transection of the pallial nerve in the common octopus (Octopus vulgaris) determines loss and subsequent restoring of two functions fundamental for survival, i.e. breathing and skin patterning, the latter involved in communication between animals and concealing. The phenomena occurring after lesion have been investigated in a series of previous studies, but a complete analysis of the changes occurring at the level of the axons and the effects on animals appearance during the whole regenerative process is still missing. Our goal is to determine the course of events following injury. Our goal is to determine the course of events following injury, from impairment to full recovery.We observed nerve regeneration, end-target re-innervation and functional reconnections between central brain and periphery, using the contralateral nerve in the same animal as internal control. The final architecture of the regenerated nervous tissue does not mirror the original structure, however functionality returns to match the phenotype of an intact octopus, and with no visible impact on the behaviour of the animal. This provides exceptional value to these findings for future studies.Summary statementHere we report events occurring after interruption of the peripheral neural circuitry inOctopus vulgaris, from the dramatic loss of normal functioning to full recovery.

17 pages, 8 figures, 4 tables.-- This article is licensed under a Creative Commons Attribution 4.0 International License, Common octopus, Octopus vulgaris, is an economically important cephalopod species. However, its rearing under captivity is currently challenged by massive mortalities previous to their juvenile stage due to nutritional and environmental factors. Dissecting the genetic basis and regulatory mechanism behind this mortality requires genomic background knowledge. A transcriptomic sequencing of 10 dph octopus paralarvae from different experimental conditions was constructed via RNA-seq. A total of 613,767,530 raw reads were filtered and de novo assembled into 363,527 contigs of which 82,513 were annotated in UniProt carrying also their GO and KEGG information. Differential gene expression analysis was carried out on paralarvae reared under different diet regimes and temperatures, also including wild paralarvae. Genes related to lipid metabolism exhibited higher transcriptional levels in individuals whose diet includes crustacean zoeas, which had an impact over their development and immune response capability. High temperature induces acclimation processes at the time that increase metabolic demands and oxidative stress. Wild individuals show an expression profile unexpectedly similar to Artemia fed individuals. Proteomic results support the hypothesis revealed by transcriptional analysis. The comparative study of the O. vulgaris transcriptomic profiles allowed the identification of genes that deserve to be further studied as candidates for biomarkers of development and health. The results obtained here on the transcriptional variations of genes caused by diet and temperature will provide new perspectives in understanding the molecular mechanisms behind nutritional and temperature requirements of common octopus that will open new opportunities to deepen in paralarvae rearing requirements, Proteomic and statistics analysis was performed in the SCSIE University of Valencia that belongs to ProteoRed PRB2-ISCIII, supported by grant PT13/0001 (PE I + D + i 2013–2016) funded by ISCIII and FEDERPT13/0001. This work was funded by “AGL20134910- C02–2R” and “AGL2017-89475-C2-1R” research projects from the Spanish Ministerio de Economía, Industria y Competitividad. P. García-Fernández thanks (PhD student “Marine Science, Technology and Management, University of Vigo”) Xunta de Galicia for his predoctoral fellowship (“Plan galego de investigación, innovación e crecemento 2011-2015 (Plan I2C)” ref. ED481A-2015/446). M. Prado-Alvarez thanks EU Marie-Sklodowska- Curie Actions for her postdoctoral contract MSC-IF-RESISGAL 659072. DGDLS is a Serra Húnter Fellow of the University of Barcelona

Octopus vulgaris constitute an important part of most suitable marine resources for human consumption, however, they can represent a source in chemical contaminants intake such as heavy metals. In this scenario, the aim of the study was the evaluation of the concentration of lead (Pb), cadmium (Cd) and mercury (Hg) in the muscle and digestive gland of octopus caught from two different locations along Campania coast (Castellammare di Stabia and Napoli) and the estimation of their weekly human intake derived from the ingestion of octopus. Analysing 38 samples showed a higher concentration of Pb in the muscle of octopus in Castellammare di Stabia than in Napoli. No statistical differences were reported for Cd, Pb and Hg concentrations in the digestive gland of octopus between two sampling sites. Differences were observed between the two tissue types, with a higher level of Cd and Pb observed in the digestive gland compared with the muscle. Noteworthy, the consumption of muscle from Castellammare di Stabia could increase Pb intake in heavy consumers of local octopus. In conclusion, the present work determines that it is important to improve strategies to minimize environmental pollution sources in these areas.

The common octopus, Octopus vulgaris, is an active marine predator known for the richness and plasticity of its behavioral repertoire, and remarkable learning and memory capabilities. Octopus and other coleoid cephalopods, cuttlefish and squid, possess the largest nervous system among invertebrates, both for cell counts and body to brain size. O. vulgaris has been at the center of a long-tradition of research into diverse aspects of its biology. To leverage research in this iconic species, we generated 270 Gb of genomic sequencing data, complementing those available for the only other sequenced congeneric octopus, Octopus bimaculoides. We show that both genomes are similar in size, but display different levels of heterozygosity and repeats. Our data give a first quantitative glimpse into the rate of coding and non-coding regions and support the view that hundreds of novel genes may have arisen independently despite the close phylogenetic distance. We furthermore describe a reference-guided assembly and an open genomic resource (CephRes-gdatabase), opening new avenues in the study of genomic novelties in cephalopods and their biology., Design Type(s)species comparison design • sequence analysis objective • sequence assembly objectiveMeasurement Type(s)whole genome sequencing assayTechnology Type(s)DNA sequencingFactor Type(s) Sample Characteristic(s)Octopus vulgaris • testis • ocean biome Machine-accessible metadata file describing the reported data (ISA-Tab format)

The aim of the present study was to determine the effect of Artemia metanauplii endogenous fatty acid (FA) metabolism in the actual availability of dietary essential fatty acids (EFA) for Octopus vulgaris paralarvae development. To this end, both Artemia metanauplii inherent radiolabelled FA metabolism and the Octopus vulgaris paralarvae FA metabolism, after being fed with Artemia metanauplii incubated with radiolabelled. FAs, were determined. Metanauplii were incubated in tissue culture plates during 12 h, with 0.3 mu M of a [1-C-14]FA, including either 18:3n-3, 20:4n-6 (ARA), 20:5n-3 (EPA) or 22:6n-3 (DHA), added individually to separate wells as their potassium salts bound to bovine serum albumin. A total of 3600 one-day-old paralarvae were reared up to 24 h in order to ensure the ingestion of a minimum amount of the labelled Artemia. Paralarvae rearing was performed in 4 L cylinder conical tanks at a density of 25 paralarvae L-1. Labelled Artemia metanauplii were added to each paralarvae rearing tank according to a specific [1-C-14]FA treatment. Artemia in vivo metabolism results showed a preferential catabolism of DHA, which was translated into (1) the lower incorporation of this FA into Artemia total lipids (TL) (2) the highest amount of de novo synthesis of shorter chain-length FAs, as a result of the beta-oxidation of the original DHA substrate. The registered amounts of radiolabelled substrates incorporated into O. vulgaris paralarvae TL fed with labelled Artemia metanauplii were extremely low. Nonetheless, certain amount of intact [1-C-14]ARA and [1-C-14]EPA was recovered into octopus paralarvae TL, and particularly into polar lipid classes, suggesting the possibility of using Artemia as a vehicle to provide ARA and EPA to octopus paralarvae without interfering their bioavailability for the de novo synthesis of phospholipids. On the other hand, and despite of the high amount of [1-C-14]18:3n-3 incorporated into Artemia TL, the FAs with the highest esterification rate into Anemia TAG (18:3n-3 and DHA) were also the lowest incorporated into paralarvae TL. Therefore, the present results suggest that O. vulgaris paralarvae may have a potentially low capacity to metabolise dietary TAG, and so, Artemia may not be the most appropriate vehicle to provide DHA to paralarvae. Spanish GovernmentSpanish Government [AGL2010-22120-CO3] Fundacao para a Ciencia e a Tecnologia (FCT)Portuguese Foundation for Science and Technology [SFRH/BD/76863/2011] FCTPortuguese Foundation for Science and Technology [IF/00576/2014]