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Common octopus

The common octopus (Octopus vulgaris), a cephalopod mollusk in the family Octopodidae, is characterized by its soft, bulbous head, large prominent eyes, bilaterally symmetrical body, and eight muscular arms lined with two rows of suckers for locomotion, predation, and manipulation.^[1] It lacks an internal shell, enabling remarkable flexibility, and possesses specialized skin with chromatophores, papillae, and iridophores that allow rapid color and texture changes for camouflage.^[2] Adults typically measure 25 to 90 centimeters in total length (from mantle to arm tip), with arm spans up to three times the mantle length, and weigh 1 to 5 kilograms, though exceptional individuals can reach 3 meters across and 10 kilograms.^[1]^[2] Octopus vulgaris is part of a species complex of morphologically similar cephalopods. The nominal species is native to coastal waters of tropical and temperate seas in the eastern Atlantic Ocean (including the Mediterranean Sea) and adjacent regions, thriving in diverse benthic habitats such as rocky reefs, seagrass beds, sandy plains, and coral areas, from the intertidal zone to depths of 200 meters, though it is most abundant between 0 and 150 meters.^[1]^[2] Cryptic species within the complex occur in other areas, such as the western Atlantic (O. americanus) and Indo-Pacific regions.^[3] A benthic predator, it primarily feeds on crustaceans, bivalve mollusks, and gastropods, using its beak and venomous saliva to subdue prey, often leaving shell middens near dens.^[2]^[4] Renowned for its intelligence—considered the most advanced among invertebrates—the common octopus exhibits problem-solving, tool use, observational learning, and sensory discrimination through vision, touch, and chemoreception.^[4]^[1] It is solitary and territorial, often residing in crevices or self-made dens, and employs jet propulsion for swift escapes, ink release for disorientation, and arm regeneration for defense.^[4]^[2] Reproduction is semelparous: females lay 100,000 to 500,000 eggs in clusters, brooding them for 4 to 5 months without feeding, after which both parents die, while planktonic hatchlings settle after 1 to 2 months.^[1]^[2] With a lifespan of 1 to 2 years, it faces threats from commercial fishing, yielding tens of thousands of metric tons annually, particularly in the Mediterranean.^[1]^[2]

Taxonomy and etymology

Scientific classification

The common octopus (Octopus vulgaris Cuvier, 1797) is a cephalopod mollusk classified in the order Octopoda and the family Octopodidae. Recent genetic studies have recognized O. vulgaris as a species complex comprising at least six cryptic species that are morphologically similar but genetically distinct, including O. vulgaris (Northeast Atlantic and Mediterranean), O. americanus (West Atlantic), and others; however, it remains accepted as a single species in major databases like WoRMS.^[5]^[6] This complex exemplifies the diverse adaptations within the class Cephalopoda, which includes advanced nervous systems and predatory behaviors unique among invertebrates. Its taxonomy reflects evolutionary relationships within the subclass Coleoidea, emphasizing internal shell structures absent in nautiloids.^[6] The full scientific classification, according to the World Register of Marine Species (WoRMS), is:

Kingdom: Animalia^[6]
Phylum: Mollusca^[6]
Class: Cephalopoda^[6]
Subclass: Coleoidea^[6]
Superorder: Octopodiformes^[6]
Order: Octopoda^[6]
Family: Octopodidae^[6]
Genus: Octopus^[6]
Species: Octopus vulgaris Cuvier, 1797^[6]

This hierarchy is corroborated by the Global Biodiversity Information Facility (GBIF), which aligns on the core levels from kingdom to species while noting the species' widespread recognition in marine biodiversity databases.^[7]

Naming and synonyms

The common octopus bears the binomial name Octopus vulgaris, which was first formally described by the French naturalist Georges Cuvier in 1797.^[8] The genus name Octopus originates from the Ancient Greek words okto (ὀκτώ), meaning "eight," and pous (ποῦς), meaning "foot," alluding to the animal's eight arms.^[9] The specific epithet vulgaris derives from Latin, signifying "common" or "ordinary," reflecting its widespread distribution and abundance in coastal waters.^[8] In English, it is commonly referred to as the common octopus, common European octopus, or common Atlantic octopus; other regional names include "scuttle" or "rock scuttle" in some dialects.^[8] Internationally, equivalents include poulpe commun in French, polpo comune in Italian, and pulpo común in Spanish, among dozens of vernacular names across its range.^[8] Several junior synonyms have been proposed over time, but all are now considered unaccepted in favor of O. vulgaris. Notable examples include Octopus tuberculatus Blainville, 1826 (a direct synonym based on morphological overlap); Sepia octopus Gmelin, 1791 (an early misclassification under the genus Sepia); Octopus cassiopea Gray, 1849 (synonym); and Octopus troschelii Targioni-Tozzetti, 1869 (dubious synonym due to uncertain type material).^[8] The International Commission on Zoological Nomenclature (ICZN) affirmed the validity of Octopus vulgaris as the type species of the genus Octopus through Opinion 233 in 1955, stabilizing its nomenclature amid historical taxonomic revisions.^[8]

Description

Physical characteristics

The common octopus (Octopus vulgaris) is a soft-bodied cephalopod mollusk characterized by a sac-like mantle that encloses the visceral organs, with no external shell or protective armor. The body exhibits bilateral symmetry and lacks fins, consisting of a bulbous head from which eight muscular arms radiate, enabling a highly flexible and maneuverable form adapted for benthic lifestyles. This structure allows the octopus to squeeze through narrow crevices, as the mantle can contract to a fraction of its resting size.^[10] Adults typically reach a mantle length of up to 25 cm, with total body lengths extending to 1 m including the arms, and weights up to 4 kg, though specimens can vary regionally from 500 g to up to 10 kg in exceptional cases. The mantle is broadly oval to elongate and cylindrical, widest in the posterior half, housing the gills, digestive system, and ink sac. The head features prominent, lateral eyes with a well-developed, two-part lens and a horizontal slit-shaped pupil, providing excellent binocular vision despite color blindness, which supports prey detection and environmental navigation.^[10]^[11]^[12] The eight arms are robust, tapering to rounded tips, and measure 0.5–1 m in length, with dorsal arms slightly longer than ventral ones; they lack the ability for autotomy common in some other cephalopods. Each arm bears 180–400 suckers arranged in two longitudinal rows, which are sessile, wide-based, and lined with soft, chitinous cuticles featuring radial grooves and denticles for enhanced grip. In males, the third right arm is modified into a hectocotylus with a spermatophore groove and spoon-like ligula for reproduction. The suckers' acetabular chamber is ellipsoidal with a prominent central protuberance occupying about 80% of the volume, aiding in adhesion through a combination of suction and frictional forces via three sphincters.^[10]^[13] The skin is smooth to warty, covered in low papillae and capable of rapid texture changes via muscular control, complemented by an advanced chromatophore system for camouflage. Chromatophores, along with leucophores and iridophores, enable instantaneous color shifts from brick-red to mottled browns and whites, matching substrates in under 30 ms for concealment or signaling. Four large erectile papillae form a diamond pattern on the dorsal mantle, with additional supraocular and ocular papillae enhancing visual deception.^[10]

Size, growth, and lifespan

The common octopus (Octopus vulgaris) exhibits considerable variation in size depending on geographic location, environmental conditions, and sex, with males typically achieving larger dimensions than females. Adults commonly reach a dorsal mantle length (DML) of 10–25 cm, with total length (including arms) extending to 60–130 cm. Maximum recorded weights are approximately 5–10 kg, though individuals over 5 kg are rare; for instance, in Mediterranean populations, the largest specimens weighed 4.7 kg for females and 5.3 kg for males.^[14]^[15] Growth in O. vulgaris is rapid and indeterminate, characterized by high specific growth rates that enable juveniles to reach maturity within months. Daily body weight increase averages around 3% under optimal conditions, with subadult octopuses (starting at ~300 g) capable of attaining commercial sizes of 750 g in as little as 2.5 months when fed high-protein diets like mackerel. In wild Mediterranean cohorts, growth increments in statoliths and stylets reveal strong positive correlations between age and size (R² = 0.85–0.91), influenced by hatching season, with summer-hatched individuals showing the fastest rates. Maturity is size-dependent, occurring at ~70 mm DML for males and ~120 mm for females, often within 6–12 months post-hatching.^[14]^[16]^[17] Lifespan varies regionally and by sex, generally spanning 1–2 years, though environmental factors like temperature and food availability can extend it. In Atlantic and Mediterranean populations, most individuals live 12–18 months, with females senescing earlier and more abruptly than males due to post-reproductive physiological decline. Studies using stylet and beak increment analysis in southern Tunisian waters indicate an average of ~2.5 years for the bulk of the population, with exceptional males reaching up to 3.5 years (1,251 days). In cooler eastern English Channel habitats, lifespans are shorter at 12–15 months, reflecting faster metabolism and growth.^[18]^[19]^[20]^[17]

Distribution and habitat

Geographic range

The common octopus, Octopus vulgaris (sensu stricto), has a geographic range confined to the Eastern Atlantic Ocean and the Mediterranean Sea, reflecting its adaptation to temperate and subtropical coastal waters. This species is distributed from the southern coasts of England and the English Channel southward along the western African coastline to northwest Africa (such as Mauritania and Senegal), including the Macaronesian archipelagos such as the Azores, Madeira, and Canary Islands.^[21]^[22] In the Mediterranean, it occupies the entire basin but is absent from the cooler, lower-salinity Sea of Marmara and Black Sea due to unsuitable environmental conditions.^[21] Genetic analyses have clarified that populations previously attributed to O. vulgaris in regions like the Western Atlantic, Indo-Pacific, and parts of the Southern Hemisphere belong to a cryptic species complex, distinct from the nominate form. For instance, Caribbean and Gulf of Mexico populations represent Type I (redescribed as Octopus americanus in 2020), while those off Brazil are Type II, and South African coastal waters host Type III variants.^[21]^[3] These distinctions arise from mitochondrial DNA and morphological studies revealing significant divergence, emphasizing the nominate O. vulgaris as primarily an Eastern Atlantic-Mediterranean endemic. Isolated populations have been confirmed at remote sites, such as the St. Paul and Amsterdam Islands in the central-southern Indian Ocean, expanding the verified range beyond continental margins but still within the broader Atlantic influence. Recent genomic surveys in the Northeastern Atlantic, from Iberian waters to northwestern Africa, further support connectivity along upwelling-driven currents, though local adaptations limit broader dispersal.

Habitat preferences

The common octopus (Octopus vulgaris) occupies a wide range of benthic habitats in coastal marine environments, primarily along continental shelves and insular slopes. It is most abundant in shallow to moderate depths of 0 to 100 meters, becoming scarce beyond 100 meters and occasionally recorded up to 200 meters. This species exhibits high adaptability to diverse substrates, including rocky reefs, sandy and muddy bottoms, seagrass meadows, and coral reefs, where it selects dens for shelter to minimize predation risk.^[23] In terms of substrate preferences, O. vulgaris favors areas with structural complexity for denning, such as hard bottoms composed of rocks, stones, or shells during spawning, where densities of spawning dens can reach 1.08 per hectare at around 20 meters depth. On soft sediments like sandy or muddy areas, individuals rely on available shelters including bivalve shells, anthropogenic debris, or self-dug wells, with juveniles particularly utilizing empty bivalve shells (e.g., Laevicardium crassum or Dosinia exoleta) in sandy habitats at 5–10 meters to match their body size and enhance camouflage. Den selection is influenced by sediment granulometry, octopus size, and proximity to shore, with larger individuals less dependent on rock-based shelters and smaller ones preferring wells in coarser sands.^[24]^[25]^[26] Environmental factors such as temperature and salinity also shape habitat suitability, with O. vulgaris tolerating a broad thermal range of 7–33°C and salinities of 32–40, though optimal growth occurs between 19.5–26°C depending on life stage and region. Pre-recruit stages show preferences for bottom temperatures around 14°C and salinities near 36, often in areas with low precipitation and coarse sediments. These preferences contribute to higher abundances in temperate to subtropical coastal zones, where seasonal thermoclines may drive larger individuals to deeper waters during warmer periods.^[27]^[28]^[29]

Anatomy and physiology

Integumentary system and camouflage

The integumentary system of the common octopus (Octopus vulgaris) comprises a thin epidermis overlaid by a protective mucus layer and a thicker dermis rich in specialized cells for coloration and texture modulation. The epidermis consists of columnar epithelial cells interspersed with goblet cells that secrete PAS-positive mucus, which shields the animal from parasites, desiccation, and environmental irritants while facilitating subtle sensory functions such as light detection via embedded photoreceptor cells.^[30] Beneath this, the dermis features areolar connective tissue with blood sinuses, collagen fibers, and hyaline cartilage for structural support, alongside a PAS-positive cuticle in the upper layer that enhances barrier properties against mechanical stress.^[30] Central to this system are the dermal chromatophores, iridophores, and leucophores, which enable dynamic skin patterning. Chromatophores, numbering up to 1-2 million in adults with densities of 100-200 per mm² primarily on the dorsal surface, are elastic sacs containing pigments (red, yellow, or brown) that expand up to sevenfold in diameter through contraction of surrounding radial muscles, innervated by the central nervous system for millisecond-scale responses.^[31] Iridophores, platelet-based reflectors, produce structural colors by selectively reflecting light wavelengths and angles, complementing chromatophores to generate iridescence over seconds to minutes.^[32] Leucophores scatter broadband light to create white patches, intensifying contrast in patterns without relying on pigmentation.^[32] Camouflage in O. vulgaris exploits these components to achieve disruptive, mottled, or uniform patterns that mimic environmental features like rocks or corals, often matching specific landmarks with up to 90% similarity in brightness and texture as assessed by image analysis.^[33] Despite color blindness—limited to a single mid-wavelength visual pigment—the octopus relies on luminance and edge detection for background matching, using visual cues to deploy acute patterns lasting seconds to minutes or chronic ones persisting hours.^[33] Texture adaptation occurs via papillae, muscular hydrostats that protrude to form bumps or spikes, disrupting body outlines and guided primarily by vision rather than touch.^[32] This neural orchestration allows rapid reconfiguration of skin appearance, blending seamlessly in complex habitats like rocky seabeds in the Mediterranean or Atlantic.^[32]

Respiratory and circulatory systems

The common octopus, Octopus vulgaris, possesses a highly efficient respiratory system adapted to its active lifestyle in marine environments. Oxygen acquisition primarily occurs through paired gills, or ctenidia, housed within the mantle cavity. These gills feature a complex structure of folded lamellae—primary, secondary, and tertiary folds—that maximize surface area for gas exchange. Water enters the mantle cavity via the mouth and funnel (siphon), flows over the gill filaments in a countercurrent manner relative to blood flow, and is expelled through the funnel, facilitating the uptake of dissolved oxygen from seawater. This mechanism allows O. vulgaris to extract 35-50% of available oxygen, supporting metabolic demands during rest and activity.^[34] The gills also play a role in acid-base regulation and ammonia excretion, with epithelial cells equipped with transporters such as Na⁺/K⁺-ATPase on basolateral membranes and V-type H⁺-ATPase in endothelial cells. During perfusion, blood pH drops by approximately 0.2 units as it passes through the gills, while ammonium ion (NH₄⁺) levels decrease by about 40 μM, aiding homeostasis. Although gills are the dominant respiratory organs, O. vulgaris exhibits limited cutaneous respiration through its skin, which can contribute approximately 41% of total oxygen uptake at rest, though this decreases to about 3% when the animal is coiled, enhancing survival flexibility under various conditions including hypoxia or emersion.^[35]^[36] The circulatory system of O. vulgaris is closed and high-pressure, a rarity among mollusks, enabling efficient oxygen delivery despite the lower oxygen-carrying capacity of its copper-based hemocyanin compared to vertebrate hemoglobin. It comprises three hearts: two branchial hearts, which pump deoxygenated blood from the body through afferent branchial vessels to the gills for oxygenation, and a central systemic heart that propels oxygenated blood via the aorta to peripheral tissues. Blood flows from the vena cava to renal appendages, then to the branchial hearts, through the gills, and finally to the systemic heart, with pressures reaching 40-50 mmHg in arteries to counter hemocyanin's viscosity. This tripartite design, augmented by pulsatile veins and accessory pumps, achieves oxygen delivery rates comparable to those in active teleost fish, supporting bursts of jet-propelled locomotion.

Excretory and osmoregulatory systems

The excretory system of the common octopus (Octopus vulgaris) primarily consists of paired renal sacs, also known as nephridia, located adjacent to the branchial hearts, along with renal appendages associated with the branchial hearts and the vena cava. These structures filter blood plasma and form urine, which is expelled through urinary papillae near the base of the gills. The renal sacs receive blood from the branchial hearts and function as filtration units, where ultrafiltration occurs across the podocyte-lined epithelium, producing a primary filtrate that is modified by tubular reabsorption and secretion in the renal appendages. Ammonia, the primary nitrogenous waste product in cephalopods, is excreted mainly as ammonium ions (NH₄⁺) via the gills and renal sacs, reflecting their ammonotelic metabolism. Urine composition includes approximately 3.25% salts, 0.08% high molecular weight material, and 0.21% small organic solutes, such as kynurenic acid (76% of organic solutes), hypoxanthine (12%), and taurine (1.3%). Ammonia excretion rates vary with body mass and protein intake; for instance, in octopuses weighing 490–3460 g, rates range from 43–657 mg total ammonia nitrogen (TAN) per day when starved, increasing linearly to up to 265 mg TAN kg⁻¹ day⁻¹ at high protein feeding (9 g day⁻¹). Temperature also influences excretion, with rates scaling according to the equation U (µmol h⁻¹) = e^(14.77 - 4324.7/Ta) × M^0.896, where Ta is temperature in Kelvin and M is body mass in grams, indicating higher metabolic and excretory demands at elevated temperatures (15.5–26°C). Water and salt balance is maintained partly through uptake via the digestive gland appendages (pancreas), where ligation of these ducts leads to rapid weight loss of about 11% body mass per day due to dehydration.^[37]^[38]^[39]^[40] Osmoregulation in O. vulgaris involves active ion transport to maintain hemolymph osmolality close to or slightly hypoosmotic to seawater (approximately 90–100% of seawater osmolality), preventing excessive water influx in their marine environment. The gills play a central role, facilitating NH₄⁺ excretion and H⁺ secretion via mechanisms including Na⁺/H⁺-exchanger 3 (NHE3), V-type H⁺-ATPase (VHA), and Na⁺/K⁺-ATPase (NKA) in epithelial cells, with NH₄⁺ transport mediated by Rhesus proteins (RhP). During blood passage over the gills, pH decreases by about 0.2 units, and in acidosis (pH 7.2), gills restore pH to 7.4–7.5 while excreting NH₄⁺ at rates up to 5.14 µmol h⁻¹ and H⁺ at 5.33–9.52 pmol h⁻¹, modulated by cAMP-dependent pathways. The renal appendages contribute to ion regulation by reabsorbing Na⁺ and Cl⁻, while the skin mucus aids in osmotic and ionic balance through mucin glycoproteins and ion channels. O. vulgaris exhibits moderate osmoregulatory capacity compared to more euryhaline cephalopods, with sensitivity to salinity drops (e.g., during storm runoff), which can disrupt ion homeostasis and lead to mortality. Digestive gland ducts further support osmoregulation by absorbing water and salts post-feeding, preventing osmotic imbalance during digestion.^[41]^[42]^[37]^[43]

Nervous system and senses

The nervous system of the common octopus (Octopus vulgaris) is highly distributed and complex, comprising approximately 500 million neurons, which enables sophisticated behaviors despite the absence of a centralized vertebrate-like brain. The central nervous system (CNS) includes a brain with about 45–50 million neurons that integrates sensory information and coordinates high-level functions, such as learning and decision-making. Connected to the brain are the optic lobes, containing 120–180 million neurons dedicated to visual processing, and the peripheral nervous system, which dominates with over two-thirds of total neurons located in the arms.^[44] Each of the eight arms houses an independent nervous system, including axial nerve cords for local processing and sucker ganglia, allowing arms to perform autonomous actions like grasping or exploration even when severed, with reflexes persisting for up to three hours.^[44] This decentralized architecture contrasts with vertebrate systems, emphasizing embodied cognition where sensory-motor integration occurs peripherally.01064-0) The octopus relies on a suite of advanced senses adapted for its aquatic, predatory lifestyle. Vision is mediated by large, camera-like eyes approximately 20 mm in diameter, featuring a spherical lens with a graded refractive index for sharp focus and an everted retina containing rhabdomeric photoreceptors sensitive primarily to blue light (peak at 475 nm).^[12] These eyes provide high visual acuity of about 1.7 cycles per degree and polarization sensitivity for detecting contrast in turbid waters, though the species is likely color-blind, relying on brightness and motion for prey identification.^[12] Optic lobes process this input, supporting shape discrimination and camouflage matching.^[12] Chemosensory capabilities are crucial for foraging and social cues, with paired olfactory organs near the mantle cavity entrance housing a pseudo-stratified epithelium of olfactory sensory neurons (OSNs) that detect waterborne chemicals like amino acids from distant prey.^[45] These organs exhibit plasticity, including cell turnover and shape changes for enhanced detection, connecting via olfactory nerves to dedicated brain lobes.^[45] Contact chemoreception occurs through epidermal receptors and the thousands of suckers per arm, which integrate chemical sampling with tactile exploration, enabling rapid prey identification (up to 88.9% accuracy) faster than vision alone.^[46] Tactile sensing is highly refined via the arms and suckers, which contain dense arrays of mechanoreceptors and proprioceptors for texture discrimination, object manipulation, and spatial mapping without a somatotopic brain representation.^[47] Balance and orientation are maintained by paired statocysts, balloon-shaped structures with a macula-statolith system for gravity detection and a crista-cupula system with hair cells for angular acceleration, contributing to low-frequency sound perception through particle motion sensitivity.^[48] A lateral line analogue on the head and arms detects water movements, aiding in predator avoidance and navigation, though hearing remains primitive compared to vision or chemosensation.^[48]

Thermoregulation

The common octopus (Octopus vulgaris) is an ectothermic cephalopod, with its body temperature equilibrating rapidly with the surrounding seawater due to its high surface-area-to-volume ratio and active lifestyle. Unlike endothermic vertebrates, it possesses no physiological mechanisms for endogenous heat production or significant thermal insulation, making it a classic poikilotherm whose metabolic processes are strongly influenced by ambient temperature. Thermal tolerance spans approximately 7–33°C, though prolonged exposure outside 13–28°C can impair growth, reproduction, and survival.^[27]^[49] Behavioral thermoregulation plays a central role in managing thermal stress, as individuals actively select microhabitats to optimize body temperature based on ontogenetic stage and size. Juveniles and smaller adults (50–150 g) exhibit a preference for warmer waters around 25°C, which supports faster growth and higher metabolic efficiency, while larger adults (>200 g) favor cooler regimes near 15°C to reduce energy expenditure and extend lifespan. This size-dependent preference is achieved through habitat shifts, such as relocating to shallower, sun-warmed coastal areas or deeper, stratified waters where thermoclines provide cooler refuges. In aquaculture settings, aligning rearing temperatures with these preferences—25°C for small octopuses and 15°C for large ones—maximizes specific growth rates (up to 2.5% day⁻¹) and protein utilization efficiency (over 30%).^[50]^[50] At the molecular level, O. vulgaris employs pervasive A-to-I RNA editing to fine-tune neural proteome function in response to temperature fluctuations, enabling acclimation without genetic mutations. In tropical populations exposed to 30°C waters, editing alters potassium channel transcripts (e.g., Kv1.3 and Kv1.4) to accelerate channel kinetics, compensating for slowed ion conductance in warm conditions and maintaining neuronal signaling efficiency. This post-transcriptional mechanism recodes dozens of sites across neural genes, with editing rates increasing under thermal stress to preserve synaptic transmission and axonal transport. Such adaptations are particularly vital during seasonal shifts or vertical migrations, where temperature can vary by 10–15°C over short distances.^[51] Temperature also modulates physiological responses, including oxygen consumption and specific dynamic action (SDA, the postprandial metabolic increment). SDA scope rises from ~1.4 at 13°C to ~2.2 at 28°C, reflecting heightened energetic costs of digestion in warmer water, which can limit foraging activity if not balanced by behavioral choices. Embryos and paralarvae show narrower tolerances (14–23°C preferred), with development accelerating at higher temperatures but risking yolk depletion and malformations above 21°C. Overall, these integrated behavioral and molecular strategies allow O. vulgaris to thrive across its temperate-to-tropical range, though climate-driven warming beyond 27–28°C may disrupt immunocompetence and population dynamics.

Reproduction and development

Mating behavior

The mating behavior of the common octopus (Octopus vulgaris) is characterized by male-initiated courtship displays that signal readiness to receptive females, often occurring in aquaria or natural dens during the breeding season from February to October. Males exhibit a distinctive "sucker display," raising and spreading their suckers in a fanning motion toward the female, which marks the start of the courtship phase and typically lasts until the female enters a receptive posture or retreats.^[52] This display, observed in laboratory settings, helps assess female interest and can involve subtle color changes or postural adjustments, though these are less pronounced than in some other octopus species.^[53] Once the female shows acceptance by remaining stationary or partially spreading her arms, the male approaches cautiously, often from the side or rear, and initiates copulation by grasping her mantle with his arms to position her. The male then employs his hectocotylized third right arm, which is specialized for sperm transfer, inserting it into the female's mantle cavity to deposit spermatophores—elongated sperm packets measuring up to 65 mm in length.^[54] This transfer process, documented in observations of 161 matings, occurs rapidly, with the full sequence from female introduction to spermatophore ejection taking approximately 3-4 minutes in O. vulgaris, shorter than in related species like O. cyanea.^[53] During insertion, the male may remove or displace prior spermatophores from other matings, promoting sperm competition.^[54] Females are typically polyandrous, mating with multiple males over a single reproductive event, which can extend the courtship phase across several days or encounters and results in multiple paternity within egg clutches.^[54] Copulation does not guarantee immediate fertilization, as spermatophores can remain viable in the female's mantle cavity for weeks until egg laying begins; however, post-mating, females often become aggressive toward males, ending the interaction.^[53] Experimental manipulations, such as optic gland removal or castration, do not alter these behavioral sequences, indicating they are robustly driven by innate mechanisms rather than glandular hormones alone.^[53]

Egg laying and hatching

Female common octopuses (Octopus vulgaris) typically lay their eggs in protected dens or lairs, such as under rocks, in crevices, or on sandy/muddy bottoms, where they attach them in long strings or clusters to the substrate using a specialized cement-like secretion from the oviducal glands.^[55] Fertilization occurs internally during or prior to spawning, with sperm stored from previous matings. Egg laying is an intermittent process that can span several weeks, often lasting around 35 days in the wild, during which the female produces 139,000 to 241,000 eggs on average, equivalent to 31–106 eggs per gram of body weight or up to 500,000 eggs in larger females.^[56]^[55]^[57] The number and quality of eggs can vary based on factors like diet, with females fed crustaceans producing up to five times more eggs per kilogram of body weight compared to those fed fish.^[58] Following egg laying, the female enters a brooding phase, during which she remains in the den to guard and care for the eggs, rarely venturing out to forage and thus not feeding, leading to significant weight loss. Maternal behaviors include gently cleaning the eggs with her arms to remove debris and algae, fanning water over them to oxygenate and aerate the developing embryos, and protecting them from predators by blocking the den entrance.^[57] This brooding period lasts 85–128 days in natural conditions, influenced by water temperature (typically 12.9–19.3°C), egg position within the clutch, and laying date, with warmer temperatures accelerating development.^[56] Spawning occurs year-round in many populations, with peaks from January to July (peaking in April) and October to November in subtropical regions like the Canary Islands.^[55] Hatching is also intermittent, often extending over 13–43 days, as paralarvae emerge progressively from the egg strings, facilitated by the female opening and closing the den entrance to allow exit while minimizing predation risk.^[56]^[58] Upon hatching, the planktonic paralarvae are miniature versions of adults, measuring about 2–3 mm in mantle length, and disperse into the water column; hatching success rates can reach 94–99% under optimal conditions, though without maternal care, eggs are prone to fungal contamination and failure.^[57]^[58] The female typically dies shortly after the hatching period due to senescence, having devoted her remaining energy to reproduction.^[55]

Paralarval stage

The paralarval stage of the common octopus (Octopus vulgaris) begins immediately upon hatching from eggs, marking the transition from embryonic development to a planktonic larval phase. At hatching, paralarvae measure approximately 1.0–1.5 mm in mantle length (ML) and 1.5–2.9 mm in total length, with a wet weight of about 1.4 mg, and possess three suckers per arm, giving them a squid-like appearance adapted for a pelagic lifestyle.^[59] The digestive system is fully formed at this point, featuring a U-shaped structure with descending (buccal mass, oesophagus, crop) and ascending (intestine, anus) branches, enabling immediate exogenous feeding alongside residual yolk reserves.^[60] During the early post-hatching period (0–5 days), paralarvae rely on a mix of yolk and captured prey, with the yolk fully depleting by day 5, after which growth becomes exponential. The radula surface area expands rapidly from 0.73% of the buccal mass at hatching to 34.62% by day 5, supporting increased prey processing. Over the first month, total length grows from about 3 mm (day 5) to 5.58 mm (day 35), accompanied by morphological shifts such as disproportionate arm elongation relative to the mantle, transforming the body form toward a more octopus-like structure. Sucker number per arm increases progressively, serving as an age proxy, from 3 at hatching to up to 23–25 before settlement.^[60] The planktonic phase typically lasts 30–54 days, depending on temperature (longer at cooler temperatures, e.g., 47–54 days at 21.2°C versus 30–35 days at 23°C), during which paralarvae are passively transported offshore by currents before returning to coastal benthic habitats. Settlement occurs as a transitional phase when paralarvae, now with extended arms and functional chromatophores for camouflage, attach to substrates and shift to a benthic lifestyle, often around 23 suckers per arm and a dry weight of about 9.5 mg. In the wild, diet consists primarily of small crustaceans, with crabs (e.g., Goneplax rhomboides, Liocarcinus spp.) comprising 63.9% of prey reads and 71.6% frequency of occurrence, supplemented by pteropods (15.1%), polychaetes (5.9%), ostracods (5.7%), euphausiids (3.8%), and siphonophores (2.1%); prey diversity decreases in older paralarvae (>5 suckers per arm).^[59]^[61] This stage is highly vulnerable, with elevated mortality due to predation, nutritional deficiencies (particularly in essential fatty acids like DHA/EPA), and environmental factors such as upwelling-driven dispersal, limiting survival to benthic recruitment. In aquaculture attempts, survival remains low (often <1% to settlement), highlighting ongoing challenges in replicating wild conditions for feeding and metabolic demands.^[60]^[61]

Behavior

Locomotion and movement

The common octopus (Octopus vulgaris) primarily moves by crawling across substrates using its eight flexible arms, which employ a hydrostatic muscular system to generate pushing and pulling forces. Suckers on the arms anchor to surfaces, allowing the animal to elongate proximal arm segments for propulsion while maintaining contact with at least two arms to ensure stability. This ad hoc recruitment of arms enables omnidirectional movement without reliance on central pattern generators, with direction determined by the vectorial summation of forces from the radially symmetric arms.^[62] Recent studies have highlighted the flexibility of octopus arms in facilitating complex behaviors, including 12 distinct arm actions such as shortening, elongating, bending, and torsion, which support diverse locomotion and manipulation tasks.^[63] For faster displacement, O. vulgaris employs jet propulsion swimming, expelling water through the siphon to achieve backward or head-first motion, often with arms trailing tightly behind the mantle. This mechanism supplements slower crawling and is commonly used for escape or foraging, involving synchronized arm undulations in some variants where the interbrachial web aids thrust during power strokes. Arm swimming, though less frequent, features closing and opening of arms in a rhythmic pattern to generate forward momentum.^[64] Acoustic tracking has revealed that O. vulgaris exhibits site fidelity within marine protected areas, with movement ranges typically under 1 km, informing patterns of locomotion in natural habitats.^[65] A specialized form of locomotion observed in juveniles is bipedal walking, where the octopus lifts most arms off the substrate and uses two (often the third and fourth on one side) as legs for forward or oblique progression, resembling a rolling or hopping gait. This behavior, part of anti-predator defenses, relies on differential muscle contractions to stiffen the "legs" via the hydrostatic skeleton, allowing brief aerial phases and maintaining dynamic stability due to the animal's small body mass. Adult O. vulgaris may exhibit similar but less sustained bipedal elements during heterogeneous escape sequences.^[66]

Foraging and diet

The common octopus (Octopus vulgaris) is a generalist predator with an opportunistic diet that varies by habitat, size, and prey availability, primarily consisting of crustaceans, molluscs, and teleost fishes. Studies across regions indicate that crustaceans, particularly brachyuran crabs, and bivalve mollusks dominate the diet, often comprising over 90% of consumed biomass by frequency of occurrence or index of relative importance (IRI). For instance, in the Mediterranean, molluscs account for approximately 80% of the diet, with key prey including bivalves such as Callista chione (up to 62% IRI) and Venus verrucosa, alongside crabs like those in the genus Liocarcinus (around 24% IRI).^[67]^[68] In South African waters, the swimming crab Plagusia chabrus represents 65% IRI, followed by the abalone Haliotis midae at 22% IRI, with teleosts and polychaetes as minor components (11% and 11% frequency, respectively).^[69] Larger individuals tend to target bigger prey, such as abalone shells exceeding 80 mm, while smaller octopuses favor more accessible crustaceans.^[69]^[67] Foraging occurs predominantly at night on hard-bottom substrates like rocky reefs and seagrass beds, where the octopus employs a saltatory search pattern—alternating between pauses for sensory exploration and rapid advances.^[70] It relies on chemotactile cues via its highly sensitive suckers and arms to detect prey in crevices, supplemented by visual scanning for movement, particularly in low-light conditions.^[71] Attack tactics vary by prey type: bivalves are subdued by drilling through the shell with radular rasping and salivary enzymes to inject paralytic toxins, often at non-random sites like the umbo or adductor muscle; crabs are crushed with the beak or immobilized similarly; and fishes are ambushed using a "parachute" maneuver, enveloping them with the web between arms.^[68]^[70] Prey handling can take from seconds for soft-bodied items to over an hour for heavily armored molluscs, with remains often discarded in middens near dens for later analysis of diet.^[68] Individual and population-level variability characterizes foraging strategies, with some octopuses acting as opportunistic feeders that sample broadly, while others are more selective, favoring high-value prey like preferred crabs over less palatable options such as thawed fish or mussels.^[71] In experimental settings, octopuses demonstrate behavioral flexibility, such as win-stay tactics (repeating successful choices) or avoidance of familiar low-reward sites, though reliance on advanced memory for timing prey replenishment is rare.^[71] This plasticity allows adaptation to local abundances, ensuring efficient energy intake in dynamic coastal environments, with no significant sex-based differences but ontogenetic shifts from smaller, more diverse prey in juveniles to larger, specialized items in adults.^[67]^[69] The common octopus (Octopus vulgaris) is predominantly solitary, with social interactions typically limited to brief encounters during mating or territorial disputes, and no evidence of long-term grouping or cooperative behaviors.^[72] Laboratory studies have demonstrated that O. vulgaris can recognize familiar conspecifics, exhibiting longer approach latencies and fewer physical contacts with previously encountered individuals compared to unfamiliar ones, suggesting a form of class-level individual recognition that may reduce aggression in repeated interactions—a phenomenon akin to the "dear enemy" effect in other animals. These interactions rely on visual and tactile cues, with memory of familiar individuals persisting for at least one day. Despite its asocial nature, O. vulgaris shows evidence of social learning through observational mechanisms. In a seminal experiment, naïve octopuses observed trained conspecifics selecting between red and white balls for food rewards, achieving 70-86% accuracy in choosing the rewarded color during subsequent trials—learning faster than through direct conditioning and retaining the behavior for up to five days without reinforcement.^[73] This capability highlights rudimentary social transmission of information, though it remains debated due to challenges in replication and controls, and is not indicative of complex social cognition.^[72] O. vulgaris exhibits notable intelligence, characterized by advanced associative learning, spatial memory, and problem-solving abilities. Individuals display interindividual variation in behavioral types, with "proactive" or neophilic octopuses approaching novel objects more readily and succeeding more often (up to 1.21 times higher probability) in tasks like opening puzzle boxes for food, though not necessarily faster.^[74] This flexibility extends to potential episodic-like memory, where octopuses recall specific past events to guide future actions, such as navigating to hidden food sources.^[72] Juveniles also modify their dens using available materials like shells or stones, demonstrating rudimentary tool use to enhance shelter security. Object play has been observed in O. vulgaris, including manipulation of non-food items like plastic bottles or Lego pieces without immediate functional purpose, potentially serving to exercise motor skills or explore environments—behaviors linked to cognitive development in intelligent species.^[75] Overall, these traits underscore O. vulgaris as a model for invertebrate cognition, driven by evolutionary pressures from predation and foraging in complex habitats, though its intelligence differs markedly from vertebrate forms due to a decentralized nervous system.^[72]

Ecology

Predators and anti-predator adaptations

The common octopus (Octopus vulgaris) faces predation from a diverse array of marine species across its coastal habitats in the Atlantic Ocean, Mediterranean Sea, and Indo-Pacific regions. Major predators include conger eels (Conger conger), which target octopuses in rocky substrates and rank them as the second most frequent prey item in some Northeast Atlantic populations.^[76] Bony fishes, particularly perciform species such as groupers and moray eels, represent the most taxonomically diverse group of predators, often ambushing octopuses during foraging excursions.^[77] Sharks, dolphins (e.g., bottlenose dolphins), and larger cetaceans like sperm whales also consume O. vulgaris, with sharks and rays detecting them via olfactory and electroreceptive cues.^[78] Seabirds, such as gannets, and marine mammals like seals prey on smaller or juvenile individuals near the surface.^[78] To counter these threats, O. vulgaris employs a multifaceted suite of anti-predator adaptations emphasizing crypsis, behavioral flexibility, and physical defenses. Primary among these is dynamic camouflage, achieved through rapid changes in skin color, texture, and posture via specialized chromatophores, iridophores, and papillae, allowing the octopus to match diverse substrates like sand, rock, or coral and evade visual hunters.^[79] This crypsis is often enhanced by disruptive patterning, where the octopus incorporates environmental objects like rocks or shells to break its body outline.^[78] When detection is imminent, O. vulgaris may resort to deimatic displays, rapidly paling its skin and expanding its interbrachial membrane to appear larger and more intimidating to potential predators.^[78] Behavioral strategies further bolster survival. Octopuses seek refuge in dens—natural crevices, burrows, or discarded shells—sealing entrances with stones or debris to deter intruders, a tactic particularly vital on soft sediments where suitable shelters are scarce. Ink release serves as a smokescreen, containing chemicals that disrupt a predator's senses, such as smell and vision, providing a brief window for escape.^[80] In close encounters, O. vulgaris exhibits aggressive retaliation, such as enveloping a predator's head to obscure its vision or forcing arms into gills to impair respiration, as documented in interactions with conger eels.^[76] Jet propulsion enables rapid flight, though it is energetically costly and typically a last resort.^[78] Physical and cognitive adaptations add layers of resilience. Autotomy, the voluntary detachment of arms, allows escape from bites targeting appendages, with regeneration occurring over approximately 42 days, though at a metabolic cost.^[76] Interindividual variability in responses—such as differing rates of camouflage or substrate-hiding tendencies—enables population-level adaptability to local predator pressures.^[81] Observational learning further refines these behaviors, with octopuses avoiding previously encountered threats based on social cues. These adaptations collectively underscore the species' reliance on intelligence and versatility over physical armor in a predator-rich environment.

Trophic role and interactions

The common octopus (Octopus vulgaris) occupies a mid-to-upper trophic level in coastal and benthic marine ecosystems, functioning as a secondary or tertiary consumer with a mean nitrogen stable isotope ratio (δ¹⁵N) of 11.86 ± 0.66‰ in its tissues, indicating enrichment of 2.5–3‰ over its prey.^[82] As an opportunistic generalist predator, it links lower trophic levels, such as primary consumers like zooplankton and small crustaceans, to higher predators, facilitating energy transfer across neritic and benthic food webs.^[82] In its predatory role, O. vulgaris exerts significant influence on benthic community structure through active hunting, employing camouflage, agility, and jet propulsion to capture prey. Adults primarily consume crustaceans (e.g., decapod crabs like Carcinus maenas and Pilumnus hirtellus), bivalves, gastropods, fish, and cephalopods, with diet composition varying by habitat, season, and prey availability; for instance, southern populations show a dominance of crustaceans.^[82] Juveniles and settling individuals specialize in smaller invertebrates, such as amphipods (with 90% of stomachs containing the invasive Jassa slatteryi in Mediterranean samples) and hydrozoans, potentially regulating invasive species populations and aiding native biodiversity.^[83] Paralarvae, during their planktonic phase, target mesozooplankton including copepods (Paracalanus parvus, Acartia clausi), euphausiids, and decapod larvae, with diets rich in proteins (28.26% dry weight) and lipids (9.45% dry weight) that support rapid growth.^[82] This high feeding rate and turnover contribute to controlling prey abundances, preventing overpopulation of molluscs and crustaceans in coastal habitats.^[82] Trophic interactions of O. vulgaris extend to competitive and facilitative dynamics within benthic assemblages, where its predation pressure enhances ecosystem resilience by maintaining prey diversity and reducing dominance by any single species.^[82] For example, in upwelling systems like the Iberian Canary Current, paralarval feeding on meroplankton influences zooplankton community composition, indirectly affecting primary production and larval recruitment of other invertebrates.^[61] In invaded ecosystems, such as the western Mediterranean, juveniles' preference for non-native amphipods demonstrates a role in biological control, potentially mitigating the spread of invasives like Jassa slatteryi through selective predation.^[83] Overall, as an abundant mesopredator, O. vulgaris supports food web stability, with its flexible diet allowing adaptation to environmental changes, though overexploitation could disrupt these interactions.^[82]

Human interactions

Commercial importance

The common octopus (Octopus vulgaris) is one of the most commercially significant cephalopod species worldwide, supporting extensive fisheries primarily through wild capture rather than aquaculture. Global octopus production, in which O. vulgaris plays a prominent role, reached 377,358 metric tons (MT) in 2018, more than double the 179,042 MT recorded in 1980. In Europe and North Africa, annual landings of O. vulgaris averaged approximately 110,000 MT between 2013 and 2017, with the species accounting for a major portion of cephalopod catches in these regions. It is the primary commercially harvested octopus in the European Union, where Portugal, Spain, Italy, and Greece contribute 77% of the EU's cephalopod fishery value.^[84]^[85]^[86] Key fishing grounds for O. vulgaris span the Northeast Atlantic (including Galicia and the Gulf of Cadiz in Spain, and the Algarve in Portugal) and the Eastern Central Atlantic (Morocco, Mauritania, and Senegal). In 2018, reported landings included 6,799 MT in Spain, 6,236 MT in Portugal, 40,620 MT in Morocco, 29,216 MT in Mauritania, and 11,236 MT in Senegal. Portugal's national landings totaled 5,227 MT in 2020, with over 50% from the Algarve region, primarily by artisanal fleets using pots and traps. In North Africa, the species drives rapid fishery development, with Morocco setting a quota of 18,000 MT for its first fishing season in 2019. These fisheries often involve small-scale operations, though trawling contributes in some areas.^[84]^[87]^[86] Economically, O. vulgaris holds high value, generating the highest revenue among Portuguese seafood products at an average price of 6.05 €/kg in recent years. In 2018, U.S. imports of octopus from Europe and North Africa totaled 9,216 MT valued at $119 million, with Spain serving as a major re-exporter of North African catches. The species supports employment in coastal communities, employing 1,501 fishers across 358 licensed vessels in Portugal's Algarve alone in 2019, and contributes significantly to local economies in Spain and North African artisanal sectors. Trade flows primarily to EU markets (Spain, Italy, Portugal), the U.S., and Japan, underscoring its role in global cephalopod commerce.^[87]^[84]^[86]

Aquaculture and research

The common octopus (Octopus vulgaris) has garnered significant interest for aquaculture due to its rapid growth, high market demand, and nutritional value, yet commercial-scale farming remains elusive as of 2025. Efforts to develop farming technologies have intensified in regions like Spain and Italy, driven by declining wild stocks and global consumption exceeding 100,000 metric tons annually, but production is limited to experimental and pilot stages with no industrial output reported. In Spain's Galicia region, a form of "octopus ranching" involves fattening wild-caught juveniles in offshore cages for 3-4 months to enhance market value, yielding small volumes, but this relies on wild inputs and does not constitute closed-cycle aquaculture. Challenges include high operational costs, with juveniles accounting for 41% of expenses, and technical hurdles that prevent economic viability.^[84]^[88]^[89] Key obstacles in O. vulgaris aquaculture center on the species' complex life cycle, particularly the paralarval stage, where survival rates are low due to nutritional deficiencies in live feeds like Artemia, which lack essential polyunsaturated fatty acids (PUFAs) such as docosahexaenoic acid (DHA). Cannibalism poses another major issue in high-density rearing, mitigated somewhat by providing shelters and size-grading individuals to densities no exceeding 10 kg/m³, though this increases labor costs. Reproduction in captivity has been achieved since 2001, with broodstock adapting well to recirculating aquaculture systems (RAS), but spawning success varies with diet; for instance, crustacean-based feeds (e.g., mantis shrimp and crabs) yield up to 115,928 eggs per kg body weight and 99.2% hatching rates, compared to 22,109 eggs/kg and 94.5% with fish-based diets. Growth rates in captivity can reach 13% body weight per day, with juveniles attaining 0.5-0.6 kg in 6 months and 1.6 kg in 8 months when fed low-value natural prey, but post-mortem protein degradation limits processing options.^[89]^[88]^[58] Research on welfare and environmental management is advancing to improve rearing conditions and support sustainable aquaculture. Studies in RAS demonstrate that enriched environments—incorporating substrates like PVC pipes and natural elements—increase behavioral diversity, with octopuses exhibiting 14 body patterns (e.g., camouflage) versus 9 in basic setups, alongside higher social interactions and weight gains of up to 1,373.9 g. These enrichments reduce stress indicators like hostile postures, enhancing overall growth and potentially reducing mortality in commercial trials. Recent investigations into bioactive compounds, such as plant extracts, show promise in boosting growth and welfare by modulating stress responses, while ultrasound techniques have established reliable predictors of body condition for non-invasive monitoring during farming. Additionally, assessments of stress from capture methods, using biomarkers like enzymatic activity, inform better handling protocols to minimize impacts on research and aquaculture stock.^[90]^[91]^[92]^[93] Ongoing research emphasizes nutritional optimization and genetic tools to overcome bottlenecks, with priorities including formulated feeds for paralarvae and closed-cycle reproduction to reduce reliance on wild juveniles. Projects in Europe, such as those evaluating lighting for paralarval feeding and enzymatic changes in cultured juveniles, indicate that commercial production may be feasible within the next decade if welfare standards and environmental impacts are addressed. As of 2025, proposed commercial farms, such as Nueva Pescanova's facility in Spain's Canary Islands, remain in planning stages amid ethical and environmental controversies. Ethical concerns, including sentience and suffering in intensive systems, have prompted legislative actions like a 2025 U.S. bill proposing bans on octopus farming and imports, highlighting the need for balanced sustainability assessments. Seminal work continues to build on early closures of the life cycle, positioning O. vulgaris as a high-potential candidate for diversifying aquaculture amid overfished wild populations.^[94]^[95]^[96]^[89]^[97]

Conservation

Status and threats

The common octopus (Octopus vulgaris) has not been evaluated by the IUCN Red List. Despite this, regional populations face significant pressures, particularly from overfishing in key fisheries. In the Northeast Atlantic and Eastern Central Atlantic (FAO areas 27 and 34), stocks are often fully exploited or overfished as of 2018-2019, with biomass ratios below sustainable levels in areas like Morocco (Bcur/B0.1 = 66%) and fishing mortality exceeding targets (Fcurr/FMSY > 114% in parts of Europe).^[84] Artisanal and industrial fisheries, using pots, traps, and trawls, contribute to high exploitation rates, exacerbated by illegal, unreported, and unregulated (IUU) fishing and underreporting in small-scale operations.^[98] Bycatch of non-target species, such as dolphins and sea turtles, and habitat degradation from bottom trawling further compound these issues in coastal ecosystems.^[84] Climate change poses an emerging threat by altering ocean temperatures and chemistry, potentially shifting suitable habitats for O. vulgaris. Projections indicate severe distribution losses for the species under high-emission scenarios (RCP8.5), with reduced suitability in core ranges due to warming waters disrupting embryonic development, protein function in vision, and overall metabolic rates.^[5]^[99] Additionally, the species is sensitive to pollutants, including heavy metals and plastics, which accumulate in coastal habitats and impair physiological processes.^[100] While aquaculture development could alleviate wild harvest pressure, current proposals raise concerns over disease transmission and escapes impacting wild stocks, though it remains limited globally.^[84]

Protection and management

Protection and management of O. vulgaris primarily occur through fishery regulations, as the species faces overexploitation in key regions like the Mediterranean, eastern Atlantic, and northwest Africa, where annual catches exceed 50,000 tonnes globally. The common octopus (Octopus vulgaris) has not been evaluated by the IUCN Red List, but ongoing monitoring is recommended for regional declines due to fishing pressures. In the European Union, cephalopod fisheries fall outside total allowable catch quotas under the Common Fisheries Policy, relying instead on national and regional measures to control effort and protect juveniles. For instance, Spain enforces a minimum landing size of 1 kg whole weight in the Gulf of Cádiz, coupled with closed seasons from May 1 to June 15 and September 15 to October 30 since 2017, to allow spawning recovery; similar restrictions apply in Galicia (May 29 to July 1) and Asturias (February 1 to May 1 outside designated plans).^[84]^[84] In Portugal, management includes a minimum landing weight of 750 g, limits on traps (up to 3,000 non-baited or 750–1,250 baited per vessel), and a weekend fishing ban since 2019 to reduce overall effort in small-scale artisanal fisheries, which dominate the sector and employ participatory approaches for local decision-making. The International Council for the Exploration of the Sea (ICES) supports these efforts through its Working Group on Cephalopod Fisheries, providing stock assessments and advice, though data gaps persist for precise biomass estimates. One notable success is the Marine Stewardship Council certification of the western Asturias trap fishery in Spain, which incorporates genetic monitoring to ensure sustainability and has maintained stable landings since 2010.^[84]^[101]^[19] North African fisheries, assessed by the FAO's Committee for Eastern Central Atlantic Fisheries, implement similar protective measures amid rising export demands. Morocco sets seasonal total allowable catches, enforces closed periods in spring and autumn, mandates a minimum market size of 500 g, and restricts operations to waters beyond 10 nautical miles with bans on certain trawls since 2018. Mauritania applies two-month closures in autumn (since 1996) and spring (since 2008), a 500 g minimum eviscerated weight, 70 mm trawl mesh sizes, and trawling prohibitions in depths under 20 m to safeguard shallow habitats. In Senegal, fleet-specific quotas, seasonal bans, a 350 g whole or 300 g eviscerated minimum landing weight, and individual transferable quotas via local councils aim to balance artisanal and industrial sectors, though enforcement challenges contribute to moderate management effectiveness ratings.^[102]^[84]^[84]^[84] Beyond fisheries, emerging protections address indirect threats; for example, Washington's 2024 ban on commercial octopus farming highlights welfare and ecological concerns, potentially reducing incentives for wild overharvesting by promoting alternatives. In 2025, California became the second U.S. state to prohibit octopus farming and sales of farmed octopus. Federally, the OCTOPUS Act was reintroduced in June 2025 to ban commercial octopus aquaculture operations and imports of farmed octopus nationwide.^[103]^[104] Overall, these measures prioritize juvenile protection and effort reduction, with pot and trap methods rated highly sustainable compared to trawling, which exacerbates bycatch and habitat damage.^[84]

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On the reproduction of Octopus vulgaris off the coast of the Canary ...
Males die after mating and females die after eggs hatch. The aim of this paper is to provide information on the reproductive cycle of O. vulgaris in waters off ...
[50]
new insights from a female Octopus vulgaris in the wild | Journal of ...
The brooding period, the egg laying interval and the duration of the hatching course lasted 128, 35 and 43 days, respectively. Both egg laying and hatching were ...
[51]
A practical staging atlas to study embryonic development of Octopus ...
1a) [4, 5]. Octopuses that lay eggs that hatch out as planktonic paralarvae generally produce thousands of small eggs, reaching 500,000 in O. vulgaris [6].
[52]
Evaluation of reproductive performances of the common octopus ...
Sep 17, 2020 · Evaluation of reproductive performances of the common octopus (Octopus vulgaris) reared in water recirculation systems and fed different diets.
[53]
Rearing of Octopus vulgaris paralarvae: Present status, bottlenecks ...
Jun 1, 2007 · This paper describes rearing techniques for the O. vulgaris paralarvae used by the different research participant teams, with regard to tank systems, feeding ...
[54]
https://pmc.ncbi.nlm.nih.gov/articles/PMC6794433/
[55]
Trophic ecology of Octopus vulgaris paralarvae along the Iberian ...
May 30, 2023 · Our knowledge of the diet of wild octopus paralarvae, Octopus vulgaris, is restricted to the first 2 weeks of its planktonic phase when they ...
[56]
https://www.cambridge.org/core/journals/journal-of-the-marine-biological-association-of-the-united-kingdom/article/from-brooding-to-hatching-new-insights-from-a-female-octopus-vulgaris-in-the-wild/66CB052E583951A953EF24627EA0003A
[57]
(PDF) Swimming Patterns of the Octopus Vulgaris - ResearchGate
Mar 16, 2016 · Although jet swimming is more frequently observed, relying primarily on the siphon, arm swimming has been encountered {kazakidi, zabulis, ...
[58]
https://www.nature.com/articles/s41598-020-72151-y
[59]
Diet of Octopus vulgaris from the Moroccan Mediterranean Coast
May 9, 2018 · In this paper the diet of octopus was studied by analyzing the stomach contents of 365 specimens obtained throughout the year from commercial catches.Missing: scientific paper
[60]
Predation by Octopus vulgaris in the Mediterranean - Ambrose - 1983
Collections of prey discards in octopus middens and in areas inhabited by octopuses revealed that molluscs comprise an estimated 80% of the O. vulguris diet.
[61]
Diet of Octopus vulgaris in False Bay, South Africa - ResearchGate
Aug 10, 2025 · Diet of Octopus vulgaris in False Bay, South Africa. January 2003; Marine Biology 143(6):1127-1133. DOI:10.1007/s00227-003-1144-2. Authors:.
[62]
Behavioral dynamics provide insight into resource exploitation and ...
Multiple octopus species inhabit overlapping ecohabitats worldwide yet little is known about the behavioral mechanisms that facilitate such coexistence.
[63]
Octopus vulgaris use multiple and individually variable strategies in ...
Oct 12, 2022 · Field studies show that common octopuses use different foraging strategies, with some being opportunistic and others selective, and ...
[64]
How intelligent is a cephalopod? Lessons from comparative cognition
Sep 6, 2020 · Social learning has been reported in the common octopus, Octopus vulgaris, whereby naïve octopuses were able to solve a colour discrimination ...
[65]
Observational Learning in Octopus vulgaris
### Summary of Observational Learning Experiment in Octopus vulgaris
[66]
Octopus vulgaris Exhibits Interindividual Differences in Behavioural ...
Dec 4, 2023 · Here, we investigated how Octopus vulgaris approached and solved a problem required for obtaining food from a puzzle box.
[67]
Fun and play in invertebrates - ScienceDirect.com
Jan 5, 2015 · To date, the only form of play demonstrated experimentally in octopuses is object play, which serves an obvious function in exercising muscle ...
[68]
https://onlinelibrary.wiley.com/doi/10.1111/j.1439-0485.1983.tb00299.x
[69]
Octopus vulgaris, the common octopus - ScienceDirect.com
Perciform fishes are the most diverse taxa of predators, followed by dolphins and sharks. Besides being a vector of harmful algal bloom toxins, O. vulgaris ...Missing: scientific | Show results with:scientific
[70]
https://www.sciencedirect.com/science/article/abs/pii/S0022098121000824
[71]
https://journals.biologists.com/jeb/article/225/19/jeb244234/277242/Unruly-octopuses-are-the-rule-Octopus-vulgaris-use
[72]
https://onlinelibrary.wiley.com/doi/10.1111/brv.12651
[73]
Anti-predator behavior of Octopus vulgaris, December 2016
Because of their soft bodies and lack of hard, protective outer covering octopuses are highly vulnerable to numerous predators. However, octopuses have evolved ...Missing: scientific review
[74]
[PDF] Ecology of the Common Octopus Octopus vulgaris (Cuvier
Nov 22, 2013 · Population biology of Octopus vulgaris on the temperate south-eastern ... paralarval stage affecting the present generation recruitment to ...<|control11|><|separator|>
[75]
Octopus diet during the settlement period using DNA metabarcoding
Jul 24, 2024 · The diet of recently settled Octopus vulgaris from a Mediterranean sandy bottom was studied through molecular methods.
[76]
[PDF] Common octopus - Seafood Watch
Mar 1, 2021 · The vertical overlap is also considered as high, as a wide range of depths are fished by the different gears used for targeting octopus. The ...
[77]
(PDF) World Octopus Fisheries - ResearchGate
Aug 6, 2025 · The common octopus Octopus vulgaris is a species with high commercial value that supports the most intense octopus fishery of the world (Sauer ...<|control11|><|separator|>
[78]
Fisheries for common octopus in Europe: socioeconomic importance ...
The common octopus (Octopus vulgaris) is the most important commercially harvested octopus species in the EU. ... Spawners prefer areas of moderate depth with ...
[79]
Environmental assessment of common octopus (Octopus vulgaris ...
Jun 8, 2022 · Common octopus is the fishing species with highest economic revenue in Portugal, and its consumption per capita is very high.
[80]
[PDF] Aquaculture of Octopus species: present status, problems ... - PEARL
Jul 1, 2011 · Abstract. The aquaculture of Octopus species is currently an active field of research around the world, but economic viability is not yet ...
[81]
Aquaculture potential of the common octopus (Octopus vulgaris ...
The potential for aquaculture of the cephalopod species Octopus vulgaris is evaluated, taking into consideration biological and physiological ...Missing: research | Show results with:research
[82]
Effects of Environmental Enrichment on the Behavior of Octopus ...
The results showed that octopuses kept in an enriched environment showed significantly more body patterns and gained significantly more weight than the ...
[83]
Effect of natural bioactive compounds on growth and welfare in ...
The aquaculture of Octopus vulgaris is gaining interest due to its high demand, rapid growth, and nutritional value. However, significant challenges remain, ...
[84]
Ultrasound measurements reveal predictable relationship between ...
Sep 15, 2025 · There has been a great interest in common octopus Octopus vulgaris aquaculture in recent years and commercial production is within reach.
[85]
Stress Induced by Fishing in Common Octopus (Octopus vulgaris ...
Also, the HSP70 gene resulted upregulated in males, which could be due to the effect of thermal stress occurring during the fishing and transportation ...
[86]
Changes in enzymatic activity and nutritional reserves of cultured ...
Aug 20, 2025 · Octopus vulgaris has a high market price and great potential for aquaculture diversification, due to fast growth and high conversion rates (Vaz- ...
[87]
Investigating lighting intensity and angle to facilitate feeding in ...
Aug 15, 2025 · This study investigated the ingestion of prey by Octopus tetricus paralarvae, aged 2 days post hatch, under different combinations of light intensity.
[88]
Octopus Farming in the U.S. Doesn't Exist, and a New Bill Wants to ...
Jun 24, 2025 · A bill that seeks to prohibit commercial octopus aquaculture operations in the United States and the import of farmed octopus.<|control11|><|separator|>
[89]
Octopus vulgaris, Common octopus : fisheries - SeaLifeBase
Octopus vulgaris, or common octopus, is found in temperate and tropical seas, reaching 180cm, and is commercially fished, especially in the Mediterranean.
[90]
https://www.mdpi.com/2076-2615/13/11/1862
[91]
Projecting future climate change impacts on the distribution of the ...
Historically, O. vulgaris was considered a cosmopolitan species, inhabiting shallow benthonic waters in disjunct populations spread around tropical waters ...Missing: sources | Show results with:sources
[92]
Projected ocean temperatures impair key proteins used in vision of ...
Apr 4, 2024 · These mechanisms include induction of heat shock proteins such as molecular chaperones, which had significantly elevated levels in the octopus ...
[93]
Octopus | National Wildlife Federation
Octopuses are marine mollusks with eight arms, three hearts, blue blood, and are intelligent, solitary, and excellent at camouflaging. They are about 90% ...
[94]
https://link.springer.com/article/10.1007/s10499-025-02194-3
[95]
https://www.sciencedirect.com/science/article/pii/S0044848625004466
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OCTOPUS Act - Animal Welfare Institute
The OCTOPUS Act would proactively protect octopuses from inhumane farming conditions and establish the United States as a global leader in animal welfare and ...