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These animals have a life span of 12 to 24 months.
There is the potential for the overfishing of these animals, which threatens their proliferation. However, at this time, they are not at any specific risk.
The duration of embryonic development is related to temperature, as it is in all cephalopods, and it also depends on the size of the egg.
In 1975, some 121,000 tons of O. vulgaris were caught by fisheries. In 1976, the number was 137,000 tons.
Octopus vulgaris are active predators that feed primarily on gastropods and bivalves. Small hatchlings typically spend several weeks as active predators in the plankton before they settle down to the benthic mode of life at a size of about 0.2 grams.
Reach 1-3 feet in length including arms. The skin is smooth. Like other octopuses, members of this species have 8 arms that are lined with suckers, and they lack any internal shell.
Other Physical Features: ectothermic ; bilateral symmetry
Octopus vulgaris is found in tropical, subtropical, and temperate waters between the surface and a depth of 100 to 150 meters. . It is not found in polar or subpolar regions. It lives in costal waters and the upper part of the continental shelf.
Habitat Regions: temperate ; tropical
Aquatic Biomes: benthic ; reef ; coastal
This species has a world-wide distribution. It is abundant in the Mediterranean Sea, the Eastern Atlantic Ocean, and in Japanese waters.
Biogeographic Regions: indian ocean (Native ); atlantic ocean (Native ); pacific ocean (Native )
Octopus vulgaris has individuals of both sexes. During mating, the male approaches the female, who fends him off for a while, but then accepts him. He sits next to her or mounts her, inserting the hectocotylus in her mantle cavity to pass the spermatophores. They may copulate for several hours. The same pair often repeat mating over a period of a week or so, but a male copulates with other females and a female accepts other males. Mating often occurs when the females are immature. Only females ready to lay eggs consistently fend off the males.
Mating System: polygynandrous (promiscuous)
Females become restless and search for a sheltered place where they can lay and brood the eggs without disturbance. The spermatophores are placed in the oviducts and empty cases are discarded. Fertilization takes place in the oviductal glands as the mature eggs pass through them on thir way out of the oviducts. Two secretions from the oviductal glands, together with the mucus, are used to stick the egg stalks together in strings and attach these to a substrate. Eggs are laid in shallow water. They are always attached to a substrate. On rocky shores, females find a hole, a crevice or sheltered place and they often protect their homes with shells, stones and other solid objects that they gather. Coral reefs provide suitable shelter. On sandy or muddy bottom, eggs are laid in empty mollusc shells or in man-made objects such as cans, tins, bottles, tires, boots, and amphorae . In tropical and subtropical waters, eggs are laid throughout the year. The total number of eggs laid by a female varies from 100,000 to 500,000. During egg laying and subsequent brooding, the female rarely leaves the egg mass. She usually does not feed during the entire period of spawning and brooding, which can be as long as 4-5 months at low temperatures. Egg care includes cleaning the eggs with the arm tips and directing jets of water from the funnel through the strings. Intruders, including potential prey, are pushed away, although crabs left overnight may occasionally be eaten. As a rule, females die shortly after the hatching of the last embryos after losing one-third of their pre-spawning weight.
Range number of offspring: 100000 to 500000.
Key Reproductive Features: semelparous ; seasonal breeding ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); oviparous
Die Gewone seekat (Octopus vulgaris) is 'n seekat wat dwarsoor die wêreld, en ook langs die hele kus van Suid-Afrika voorkom. In Engels staan die seekat bekend as die Common octopus.
Die seekat word tot 300 mm lank. Die lyf is sag, rond en bevat geen bene of dop nie. Die dier het agt arms elk met twee rye suiers op. Die mannetjie se derde arm is klein en lepelvormig en word gebruik om sperm na die wyfie oor te dra. Die seekat leef in vlak poele, koraal- en rotsriwwe in water tot 200 m diep is. Hulle vreet krappe, krewe en vis.
Die Gewone seekat (Octopus vulgaris) is 'n seekat wat dwarsoor die wêreld, en ook langs die hele kus van Suid-Afrika voorkom. In Engels staan die seekat bekend as die Common octopus.
El pop roquer (Octopus vulgaris) és l'espècie més estudiada de totes les espècies de polps. La seva distribució natural va des del mar Mediterrani i les costes del sud d'Anglaterra fins al Senegal. N'hi ha a les Açores, illes Canàries, i illes de Cap Verd.[1]
El mant del cos fa fins a 25 cm de llargada i amb els braços un total d'1 metre. Cada any se'n pesquen unes 20.000 tones. S'alimenta principalment de crancs i mol·lusc bivalves, però menja gairebé qualsevol animal que pugui capturar, incloent de la seua pròpia espècie.[2] Pot canviar de color. Com els pops en general, són animals relativament intel·ligents.
El pop roquer (Octopus vulgaris) és l'espècie més estudiada de totes les espècies de polps. La seva distribució natural va des del mar Mediterrani i les costes del sud d'Anglaterra fins al Senegal. N'hi ha a les Açores, illes Canàries, i illes de Cap Verd.
Chobotnice pobřežní (Octopus vulgaris) je hlavonožec z čeledi chobotnicovití (Octopodidae). Pochází ze Středozemního moře a východního Atlantiku.[1][2]
Chobotnice pobřežní má velikost pláště až 25 cm s rameny až 1 m dlouhými.[3]
Chobotnice pobřežní pochází ze Středozemního moře a z východního Atlantiku od jižní Anglie po Senegal, od mělčin do hloubky asi 100 metrů. Preferuje oblasti se skalnatým nebo kamenitým dnem, vzácně se vyskytuje i na písčinách.
Chobotnice je odděleného pohlaví. Sameček pomocí ramen přenáší spermie k samičce – má přímý vývoj.
Je významným úlovkem rybářů, ročně je uloveno přibližně 20 000–100 000 tun chobotnic pobřežních.
Obrázky, zvuky či videa k tématu chobotnice pobřežní ve Wikimedia Commons
Chobotnice pobřežní (Octopus vulgaris) je hlavonožec z čeledi chobotnicovití (Octopodidae). Pochází ze Středozemního moře a východního Atlantiku.
Der Gewöhnliche Krake oder Gemeine Krake (Octopus vulgaris), teilweise nur Oktopus (Plural Oktopoden) genannt, ist ein Kopffüßer aus der Ordnung der Kraken.
Das Pallium (die mantelartige Rückenoberfläche) des Gewöhnlichen Kraken besitzt eine weite Öffnung und wird bis zu 25 Zentimeter lang; die Fangarme erreichen eine Länge bis zu einem Meter und sind mit zwei Reihen Saugnäpfen besetzt. Die dorsalen (rückwärtigen) Arme sind am kürzesten. Die lateralen (seitlichen) Arme sind länger als die ventralen (vorderen), die ventrolateralen Arme sind nur etwas länger als die dorsolateralen Arme. Der Sipho ist W-förmig. Ein Tintensack ist vorhanden. Der Gewöhnliche Krake besitzt keine Ocelli (Punktaugen) zwischen den Augen und der Basis der lateralen Arme. Der Gewöhnliche Krake hat keine Schale. Das befähigt ihn zu großer Beweglichkeit und macht es ihm möglich, sich durch engste Öffnungen zu zwängen.[1]
Der Gewöhnliche Krake kommt weltweit in den Meeren der tropischen und gemäßigten Zone vor, am häufigsten nahe Großbritannien und der südostasiatischen Küste. Der Gewöhnliche Krake sensu stricto ist möglicherweise nur in europäischen und nordafrikanischen Gewässern verbreitet, während es sich bei den übrigen Populationen um Vertreter von mindestens vier Arten handelt, die sich morphologisch nicht vom Gewöhnlichen Kraken unterscheiden lassen. Die Unterscheidung ist nur durch molekulargenetische Untersuchungen möglich, und die Erstbeschreibung der betreffenden Arten steht noch aus.[2]
Die Art besiedelt das Benthos von der Küste bis zum äußeren Rand der Kontinentalschelfe in Tiefen bis 200 Meter, wo der Gewöhnliche Krake eine Vielzahl von Lebensräumen wie Felsen, Korallenriffen und Seegraswiesen vorfindet.
Nachweise von Octopus vulgaris liegen aus allen Weltmeeren vor, wobei sich die Systematiker einig darüber sind, dass es sich um einen Artenkomplex handelt. Die Beziehungen zwischen den einzelnen Populationen sind noch nicht näher untersucht.
Der Gewöhnliche Krake ernährt sich hauptsächlich von Krebstieren (Krabben und Hummerartigen) sowie Weichtieren (Muscheln und Schnecken).
Weibchen produzieren zwischen 120.000 und 400.000 Eier, die in Schnüren vor allem in Spalten und Höhlen seichter Gewässer abgelegt werden. Die Eiablage kann sich bis zu einem Monat hinziehen. Während der Brutzeit (25–65 Tage, abhängig von der Wassertemperatur) nehmen die Weibchen fast keine Nahrung zu sich, weshalb viele nach dem Schlupf der Paralarven sterben. Der sich entwickelnde Krake (Paralarve) ist planktonisch.
Der Gewöhnliche Krake lebt in freier Wildbahn bis zu zwei Jahre, kann jedoch in Gefangenschaft unter optimalen Haltungsbedingungen bis zu drei Jahre alt werden.[3]
Der Gewöhnliche Krake wird vor allem für den menschlichen Verzehr gefangen und als fangfrische Ware, gefroren oder getrocknet und gesalzen angeboten. Nach den Angaben der Food and Agriculture Organization wurden 1999 34.262 Tonnen gefangen, wobei Mexiko mit 19.081 und Italien mit 8.844 Tonnen die größten Mengen fingen.
Generell sinken die Fangmengen seit den späten 1960er Jahren. Damals wurden mehr als 100.000 Tonnen pro Jahr gefangen.
Der Gewöhnliche Krake oder Gemeine Krake (Octopus vulgaris), teilweise nur Oktopus (Plural Oktopoden) genannt, ist ein Kopffüßer aus der Ordnung der Kraken.
De Eenfache Krake oder Slichte Krake (Octopus vulgaris), ok woll fökener bloß Oktopus (Plural Oktopoden) nömmt, höört to de Koppfööt, un dor to de Ornen vun de Kraken mit to.
Den Eenfachen Kraken sien Mantel steiht wiet open un warrt bit hen to 25 cm lang. De Fangarms könnt bit hen to een Meter lang weern. Dor sitt twee Regen mit Suugproppens an. Düsse Kraken hefft en Dintenbüdel. Vunwegen datt de Slichte Krake keen Buten- un ok keen Binnenskelett hett, kann he sik bannig goot rögen un kummt allerwegens dör, ok wenn dat bannig eng is.[1]
De Eenfache Krake leevt in de Tropen un in de matigen Zonen in de See up de ganze Welt. An’n fökensten antodrepen is he nich wiet af vun Grootbritannien un de Küst vun Süüdoostasien. De Aart leevt up’n Grund vun de See, bit hen to 200 m deep, an den üteren Rand vun de Kontinentalschelfe. Dor gifft dat allerhand verscheden Levensrüme, as Felsen, Korallenriffe un Seegraswischen.
Octopus vulgaris is in all Seen up’e Welt funnen wurrn. Systematikers meent, dor hannelt sik dat um en Aardenkumplex bi un nich bloß um en enkelte Aart. Wie de allerhand Populatschonen tosamenhangt, is noch nich akraat unnersocht wurrn.
De enfache Krake fritt sunnerlich Kreefte (Krabben un Hummers) un Weekdeerter (Musseln un Sniggen).
De Seken produzeert twuschen 120.000 un 400.000 Eier un leggt de as Snöre af in Klöven un Höhlen in siede Waters. Dat Afleggen vun de Eier kann sik bit to en Maand lang hentrecken. In de Brödeltied (25-65 Dage, dat hangt vun de Temperatur vun’t Water af) fritt dat Seken meist nix. Vundeswegen gaht allerhand Krakenmudders ok in, wenn de Larven utkrapen sünd. De Larve, wenn se sik entwickeln deit, höört to dat Plankton mit to. Buten in’e See kann de Eenfache Krake bit hen to twee Johre oold weern, man wenn he bi Minschen optimal holen warrt, kann he ok bit hen to dree Johre oold weern.[2]
De Eenfache Kraken warrt sunnerlich to’n Eten fungen un kummt fangfrisch, fraren oder dröögt un solten up’n Markt. De Food and Agriculture Organization seggt, in dat Johr 1999 sünd 34.262 Tons fungen wurrn, dormank 19,081 Tons ut Mexiko un 8.844 Tons ut Italien. Generell kann seggt weern, datt de Fangtahlen vun de laten 1960er Johre af an torüch loopt. Dormols sünd mehr, as 100.000 Tons in’t Johr fungen wurrn.
. Mehr Biller, Videos oder Audiodateien to’t Thema gifft dat bi Wikimedia Commons. De Eenfache Krake oder Slichte Krake (Octopus vulgaris), ok woll fökener bloß Oktopus (Plural Oktopoden) nömmt, höört to de Koppfööt, un dor to de Ornen vun de Kraken mit to.
De Gewéinlechen Tëntefësch (Octopus vulgaris) ass eng Aart aus der Famill vun den Octopodidae. Si kënnt am ëstlechen Atlantik vum Mëttelmier bis virun d'Küst vu Senegal vir, an och ronderëm den Inselen déi do sinn,[1] an och am westlechen Atlantik[2].
Den O. vulgaris kann eng Kierperlängt vu bis zu 25 cm erreechen, mat Äerm, déi bis zu 1m laang ginn.[1] All Joer gi méi wéi 20.000 Tonnen O. vulgaris virun der Nordwestküst vun Afrika gefaangen.[1]
De Gewéinlechen Tëntefësch jot, wann et ufänkt däischter ze ginn, virun allem Krabben, Kriibsen a Muschelen. E ka seng Faarf der Ëmgéigend upassen. E fänkt seng Beit, andeems e mat sengem Spaut e Gëft ausstéisst, a se da mat sengen Tentakele gräift.
De Gewéinlechen Tëntefësch ass déi Aart vun Tëntefësch déi am beschten erfuerscht ass. Experimenter hu gewisen, datt en och relativ intelligent ass, sou kann en z. B. en Amaachglas opschrauwen, fir un eng Belounung ze kommen, déi dran ass. Si hunn et och eraus, wéi een an Hommard-Falen eran- an nees erauskënnt (nodeem den Hommard gefriess gouf).
De Gewéinlechen Tëntefësch (Octopus vulgaris) ass eng Aart aus der Famill vun den Octopodidae. Si kënnt am ëstlechen Atlantik vum Mëttelmier bis virun d'Küst vu Senegal vir, an och ronderëm den Inselen déi do sinn, an och am westlechen Atlantik.
'O purpo commune (Octopus vulgaris Cuvier, 1797) è nu cefalopode d''a famiglia d''e Octopodidae. Nc'è songo 289 specie deverze specie 'e purpe, nu bbuon tierzo 'e tutt'ê specie 'e cefalopode note 'int'ô munno.
Pô cagnà culore velocemente assaje e cu granne precisione 'int'ô dettaglio. Grazzie a chesta abbeletà n'esce a mimetizzarse e a parlà cu 'e pare suje. Caratteristeca prencepale è 'a presenza 'e na duppia filera 'e ventose ncoppa agnuno d''e otto rranfe che 'o sparte d''o purpo muscariello (cu diece rranfe ed na sola filera 'e ventose).
È nu mollusco spannuto assaje 'int'ê vasce funnale, nun cchiù ca 'e 100 m.
Ang Karaniwang Pugita (Octopus vulgaris) ay isa sa mga pinakainaral na mga uri ng pugita. Ang likas nitong tirahan ay nagmumula sa Dagat Mediteranyo hanggang katimugang baybayin ng Inglatera at sa Senegal sa Aprika. Makikita rin ito sa Azores, Kapuluan ng Kanaryo, at Cabo Verde.[1]
Ang lathalaing ito ay isang usbong. Makatutulong ka sa Wikipedia sa nito.
'O purpo commune (Octopus vulgaris Cuvier, 1797) è nu cefalopode d''a famiglia d''e Octopodidae. Nc'è songo 289 specie deverze specie 'e purpe, nu bbuon tierzo 'e tutt'ê specie 'e cefalopode note 'int'ô munno.
Ang Karaniwang Pugita (Octopus vulgaris) ay isa sa mga pinakainaral na mga uri ng pugita. Ang likas nitong tirahan ay nagmumula sa Dagat Mediteranyo hanggang katimugang baybayin ng Inglatera at sa Senegal sa Aprika. Makikita rin ito sa Azores, Kapuluan ng Kanaryo, at Cabo Verde.
The common octopus (Octopus vulgaris) is a mollusc belonging to the class Cephalopoda. Octopus vulgaris is one of the most studied of all octopus species, and also one of the most intelligent. It ranges from the eastern Atlantic, extends from the Mediterranean Sea and the southern coast of England, to the southern coast of South Africa. It also occurs off the Azores, Canary Islands, and Cape Verde Islands. The species is also common in the Western Atlantic.
Octopus vulgaris grows to 25 cm (10 inches) in mantle length with arms up to 1 m (3.3 feet) long.[3] It lives for 1–2 years and may weigh up to 9 kg (20 pounds).[4][5] Mating may become cannibalistic.[6] O. vulgaris is caught by bottom trawls on a huge scale off the northwestern coast of Africa. More than 20,000 tonnes (22,000 short tons) are harvested annually.[3]
The common octopus hunts at dusk. Crabs, crayfish, and bivalve molluscs (such as cockles) are preferred, although the octopus eats almost anything it can catch. It is able to change colour to blend in with its surroundings, and is able to jump upon any unwary prey that strays across its path. Using its beak, it is able to break into the shells of shelled molluscs. It also possesses venom to subdue its prey.[7]
They have evolved to have large nervous systems and brains. An individual has about 500 million neurons in its body, almost comparable to dogs. They are intelligent enough to distinguish brightness, navigate mazes, recognize individual people, learn how to unscrew a jar or raid lobster traps.[8][9][10] They have also been observed keeping "gardens", in which they collect various marine plant life and algae, alongside collections of shells and rocks; this behavior may have inspired the 1969 Beatles title, "Octopus' Garden". O. vulgaris was the first invertebrate animal protected by the Animals (Scientific Procedures) Act 1986 in the UK.[11] Training experiments have shown the common octopus can distinguish the brightness, size, shape, and horizontal or vertical orientation of objects.
The common octopus has world wide distribution in tropical, subtropical and temperate waters throughout the world.[12][13][14] They prefer the floor of relatively shallow, rocky, coastal waters, often no deeper than 200 m (660 feet).[14] Although they prefer around 36 grams per liter (0.0013 lb/cu in), salinity throughout their global habitat is found to be between roughly 30 and 45 grams per liter (0.0011 and 0.0016 lb/cu in).[15] They are exposed to a wide variety of temperatures in their environments, but their preferred temperature ranges from about 15 to 16 °C (59 to 61 °F).[15] In especially warm seasons, the octopus can often be found deeper than usual to escape the warmer layers of water.[16] In moving vertically throughout the water, the octopus is subjected to various pressures and temperatures, which affect the concentration of oxygen available in the water.[15] This can be understood through Henry's law, which states that the concentration of a gas in a substance is proportional to pressure and solubility, which is influenced by temperature. These various discrepancies in oxygen availability introduce a requirement for regulation methods.[17]
Primarily, the octopus situates itself in a shelter where a minimal amount of its body is presented to the external water.[18] When it does move, most of the time it is along the ocean or sea floor, in which case the underside of the octopus is still obscured.[18] This crawling increases metabolic demands greatly, requiring they increase their oxygen intake by roughly 2.4 times the amount required for a resting octopus.[19] This increased demand is met by an increase in the stroke volume of the octopus' heart.[20]
The octopus does sometimes swim throughout the water, exposing itself completely.[15] In doing so, it uses a jet mechanism that involves creating a much higher pressure in its mantle cavity that allows it to propel itself through the water.[20] As the common octopus' heart and gills are located within its mantle, this high pressure also constricts and puts constraints on the various vessels that are returning blood to the heart.[20] Ultimately, this creates circulation issues and is not a sustainable form of transportation, as the octopus cannot attain an oxygen intake that can balance the metabolic demands of maximum exertion.[20]
The octopus uses gills as its respiratory surface. The gill is composed of branchial ganglia and a series of folded lamellae. Primary lamellae extend out to form demibranches and are further folded to form the secondary free folded lamellae, which are only attached at their tops and bottoms.[21] The tertiary lamellae are formed by folding the secondary lamellae in a fan-like shape.[21] Water moves slowly in one direction over the gills and lamellae, into the mantle cavity and out of the octopus' funnel.[22]
The structure of the octopus' gills allows for a high amount of oxygen uptake; up to 65% in water at 20 °C (68 °F).[22] The thin skin of the octopus accounted for a large portion of oxygen uptake in an in-vitro study; the estimate suggests around 41% of all oxygen absorption is through the skin when at rest.[18] This number is affected by the activity of the animal – the oxygen uptake increases when the octopus is exercising due to its entire body being constantly exposed to water, but the total amount of oxygen absorption through skin is actually decreased to 33% as a result of the metabolic cost of swimming.[18] When the animal is curled up after eating, its absorption through its skin can drop to 3% of its total oxygen uptake.[18] The octopus' respiratory pigment, hemocyanin, also assists in increasing oxygen uptake.[17] Octopuses can maintain a constant oxygen uptake even when oxygen concentrations in the water decrease to around 3.5 kPa (0.51 psi)[22] or 31.6% saturation (standard deviation 8.3%).[17] If oxygen saturation in sea water drops to about 1–10% it can be fatal for Octopus vulgaris depending on the weight of the animal and the water temperature.[17] Ventilation may increase to pump more water carrying oxygen across the gills but due to receptors found on the gills the energy use and oxygen uptake remains at a stable rate.[22] The high percent of oxygen extraction allows for energy saving and benefits for living in an area of low oxygen concentration.[21]
Water is pumped into the mantle cavity of the octopus, where it comes into contact with the internal gills. The water has a high concentration of oxygen compared to the blood returning from the veins, so oxygen diffuses into the blood. The tissues and muscles of the octopus use oxygen and release carbon dioxide when breaking down glucose in the Krebs cycle. The carbon dioxide then dissolves into the blood or combines with water to form carbonic acid, which decreases blood pH. The Bohr effect explains why oxygen concentrations are lower in venous blood than arterial blood and why oxygen diffuses into the bloodstream. The rate of diffusion is affected by the distance the oxygen has to travel from the water to the bloodstream as indicated by Fick's laws of diffusion. Fick's laws explain why the gills of the octopus contain many small folds that are highly vascularised. They increase surface area, thus also increase the rate of diffusion. The capillaries that line the folds of the gill epithelium have a very thin tissue barrier (10 µm), which allows for fast, easy diffusion of the oxygen into the blood.[23] In situations where the partial pressure of oxygen in the water is low, diffusion of oxygen into the blood is reduced,[24] Henry's law can explain this phenomenon. The law states that at equilibrium, the partial pressure of oxygen in water will be equal to that in air; but the concentrations will differ due to the differing solubility. This law explains why O. vulgaris has to alter the amount of water cycled through its mantle cavity as the oxygen concentration in water changes.[22]
The gills are in direct contact with water – carrying more oxygen than the blood – that has been brought into the mantle cavity of the octopus. Gill capillaries are quite small and abundant, which creates an increased surface area that water can come into contact with, thus resulting in enhanced diffusion of oxygen into the blood. Some evidence indicates that lamellae and vessels within the lamellae on the gills contract to aid in propelling blood through the capillaries.[25]
The octopus has three hearts, one main two-chambered heart charged with sending oxygenated blood to the body and two smaller branchial hearts, one next to each set of gills. The circulatory circuit sends oxygenated blood from the gills to the atrium of the systemic heart, then to its ventricle which pumps this blood to the rest of the body. Deoxygenated blood from the body goes to the branchial hearts which pump the blood across the gills to oxygenate it, and then the blood flows back to the systemic atrium for the process to begin again.[26] Three aortae leave the systemic heart, two minor ones (the abdominal aorta and the gonadal aorta) and one major one, the dorsal aorta which services most of the body.[27] The octopus also has large blood sinuses around its gut and behind its eyes that function as reserves in times of physiologic stress.[28]
The octopus' heart rate does not change significantly with exercise, though temporary cardiac arrest of the systemic heart can be induced by oxygen debt, almost any sudden stimulus, or mantle pressure during jet propulsion.[29] Its only compensation for exertion is through an increase in stroke volume of up to three times by the systemic heart,[29] which means it suffers an oxygen debt with almost any rapid movement.[29][30] The octopus is, however, able to control how much oxygen it pulls out of the water with each breath using receptors on its gills,[22] allowing it to keep its oxygen uptake constant over a range of oxygen pressures in the surrounding water.[29] The three hearts are also temperature and oxygen dependent and the beat rhythm of the three hearts are generally in phase with the two branchial hearts beating together followed by the systemic heart.[26] The Frank–Starling law also contributes to overall heart function, through contractility and stroke volume, since the total volume of blood vessels must be maintained, and must be kept relatively constant within the system for the heart to function properly.[31]
The blood of the octopus is composed of copper-rich hemocyanin, which is less efficient than the iron-rich hemoglobin of vertebrates, thus does not increase oxygen affinity to the same degree.[32] Oxygenated hemocyanin in the arteries binds to CO2, which is then released when the blood in the veins is deoxygenated. The release of CO2 into the blood causes it to acidify by forming carbonic acid.[33] The Bohr effect explains that carbon dioxide concentrations affect the blood pH and the release or intake of oxygen. The Krebs cycle uses the oxygen from the blood to break down glucose in active tissues or muscles and releases carbon dioxide as a waste product, which leads to more oxygen being released. Oxygen released into the tissues or muscles creates deoxygenated blood, which returns to the gills in veins. The two brachial hearts of the octopus pump blood from the veins through the gill capillaries. The newly oxygenated blood drains from the gill capillaries into the systemic heart, where it is then pumped back throughout the body.[26]
Blood volume in the octopus' body is about 3.5% of its body weight[28] but the blood's oxygen-carrying capacity is only about 4 volume percent.[29] This contributes to their susceptibility to the oxygen debt mentioned before. Shadwick and Nilsson[30] concluded that the octopus circulatory system is "fundamentally unsuitable for high physiologic performance". Since the binding agent is found within the plasma and not the blood cells, a limit exists to the oxygen uptake that the octopus can experience. If it were to increase the hemocyanin within its blood stream, the fluid would become too viscous for the myogenic[34] hearts to pump.[31] Poiseuille's law explains the rate of flow of the bulk fluid throughout the entire circulatory system through the differences of blood pressure and vascular resistance.[31]
Like those of vertebrates, octopus blood vessels are very elastic, with a resilience of 70% at physiologic pressures. They are primarily made of an elastic fibre called octopus arterial elastomer, with stiffer collagen fibres recruited at high pressure to help the vessel maintain its shape without over-stretching.[35] Shadwick and Nilsson[30] theorized that all octopus blood vessels may use smooth-muscle contractions to help move blood through the body, which would make sense in the context of them living under water with the attendant pressure.
The elasticity and contractile nature of the octopus aorta serves to smooth out the pulsing nature of blood flow from the heart as the pulses travel the length of the vessel, while the vena cava serves in an energy-storage capacity.[30] Stroke volume of the systemic heart changes inversely with the difference between the input blood pressure through the vena cava and the output back pressure through the aorta.
The hemolymph, pericardial fluid and urine of cephalopods, including the common octopus, are all isosmotic with each other, as well as with the surrounding sea water.[36] It has been suggested that cephalopods do not osmoregulate, which would indicate that they are conformers.[36] This means that they adapt to match the osmotic pressure of their environment, and because there is no osmotic gradient, there is no net movement of water from the organism to the seawater, or from the seawater into the organism.[36] Octopuses have an average minimum salinity requirement of 27 g/L (0.00098 lb/cu in), and that any disturbance introducing significant amounts of fresh water into their environment can prove fatal.[37]
In terms of ions, however, a discrepancy does seem to occur between ionic concentrations found in the seawater and those found within cephalopods.[36] In general, they seem to maintain hypoionic concentrations of sodium, calcium, and chloride in contrast to the salt water.[36] Sulfate and potassium exist in a hypoionic state, as well, with the exception of the excretory systems of cephalopods, where the urine is hyperionic.[36] These ions are free to diffuse, and because they exist in hypoionic concentrations within the organism, they would be moving into the organism from the seawater.[36] The fact that the organism can maintain hypoionic concentrations suggests not only that a form of ionic regulation exists within cephalopods, but also that they also actively excrete certain ions such as potassium and sulfate to maintain homeostasis.[36]
O. vulgaris has a mollusc-style kidney system, which is very different from mammals. The system is built around an appendage of each branchial heart, which is essentially an extension of its pericardium.[36] These long, ciliated ducts filter the blood into a pair of kidney sacs, while actively reabsorbing glucose and amino acids into the bloodstream.[36] The renal sacs actively adjust the ionic concentrations of the urine, and actively add nitrogenous compounds and other metabolic waste products to the urine.[36] Once filtration and reabsorption are complete, the urine is emptied into O. vulgaris' mantle cavity via a pair of renal papillae, one from each renal sac.[36]
Temperature and body size directly affect the oxygen consumption of O. vulgaris, which alters the rate of metabolism.[19] When oxygen consumption decreases, the amount of ammonia excretion also decreases due to the slowed metabolic rate.[19] O. vulgaris has four different fluids found within its body: blood, pericardial fluid, urine, and renal fluid. The urine and renal fluid have high concentrations of potassium and sulphate, but low concentrations of chloride. The urine has low calcium concentrations, which suggests it has been actively removed. The renal fluid has similar calcium concentrations to the blood. Chloride concentrations are high in the blood, while sodium varies. The pericardial fluid has concentrations of sodium, potassium, chlorine and calcium similar to that of the salt water supporting the idea that O. vulgaris does not osmoregulate, but conforms. However, it has lower sulphate concentrations.[36] The pericardial duct contains an ultrafiltrate of the blood known as the pericardial fluid, and the rate of filtration is partly controlled by the muscle- and nerve-rich branchial hearts.[36] The renal appendages move nitrogenous and other waste products from the blood to the renal sacs, but do not add volume. The renal fluid has a higher concentration of ammonia than the urine or the blood, thus the renal sacs are kept acidic to help draw the ammonia from the renal appendages. The ammonia diffuses down its concentration gradient into the urine or into the blood, where it gets pumped through the branchial hearts and diffuses out the gills.[36] The excretion of ammonia by O. vulgaris makes them ammonotelic organisms. Aside from ammonia, a few other nitrogenous waste products have been found to be excreted by O. vulgaris such as urea, uric acid, purines, and some free amino acids, but in smaller amounts.[36]
Within the renal sacs, two recognized and specific cells are responsible for the regulation of ions. The two kinds of cells are the lacuna-forming cells and the epithelial cells that are typical to kidney tubules. The epithelia cells are ciliated, cylindrical, and polarized with three distinct regions. These three regions are apical, middle cytoplasmic, and basal lamina. The middle cytoplasmic region is the most active of the three due to the concentration of multiple organelles within, such as mitochondria and smooth and rough endoplasmic reticulum, among others. The increase of activity is due to the interlocking labyrinth of the basal lamina creating a crosscurrent activity similar to the mitochondrial-rich cells found in teleost marine fish. The lacuna-forming cells are characterized by contact to the basal lamina, but not reaching the apical rim of the associated epithelial cells and are located in the branchial heart epithelium. The shape varies widely and are occasionally more electron-dense than the epithelial cells, seen as a "diffused kidney" regulating ion concentrations.[38]
One adaptation that O. vulgaris has is some direct control over its kidneys.[36] It is able to switch at will between the right or left kidney doing the bulk of the filtration, and can also regulate the filtration rate so that the rate does not increase when the animal's blood pressure goes up due to stress or exercise.[36] Some species of octopuses, including O. vulgaris, also have a duct that runs from the gonadal space into the branchial pericardium.[36] Wells[36] theorized that this duct, which is highly vascularized and innervated, may enable the reabsorption of important metabolites from the ovisac fluid of pregnant females by directing this fluid into the renal appendages.
As an oceanic organism, O. vulgaris experiences a temperature variance due to many factors, such as season, geographical location, and depth.[39] For example, octopuses living around Naples may experience a temperature of 25 °C (77 °F) in the summer and 15 °C (59 °F) in the winter.[39] These changes would occur quite gradually, however, and thus would not require any extreme regulation.
The common octopus is a poikilothermic, eurythermic ectotherm, meaning that it conforms to the ambient temperature.[40] This implies that no real temperature gradient is seen between the organism and its environment, and the two are quickly equalized. If the octopus swims to a warmer locale, it gains heat from the surrounding water, and if it swims to colder surroundings, it loses heat in a similar fashion.
O. vulgaris can apply behavioral changes to manage wide varieties of environmental temperatures. Respiration rate in octopods is temperature-sensitive – respiration increases with temperature.[41] Its oxygen consumption increases when in water temperatures between 16 and 28 °C (61 and 82 °F), reaches a maximum at 28 °C (82 °F), and then begins to drop at 32 °C (90 °F).[41] The optimum temperature for metabolism and oxygen consumption is between 18 and 24 °C (64 and 75 °F).[41] Variations in temperature can also induce a change in hemolymph protein levels along oxygen consumption.[41] As temperature increases, protein concentrations increase in order to accommodate the temperature. Also the cooperativity of hemocyanin increases, but the affinity decreases.[42] Conversely, a decrease in temperature results in a decrease in respiratory pigment cooperativity and increase in affinity.[42] The slight rise in P50 that occurs with temperature change allows oxygen pressure to remain high in the capillaries, allowing for elevated diffusion of oxygen into the mitochondria during periods of high oxygen consumption.[42] The increase in temperature results in higher enzyme activity, yet the decrease in hemocyanin affinity allows enzyme activity to remain constant and maintain homeostasis. The highest hemolymph protein concentrations are seen at 32 °C (90 °F) and then drop at temperatures above this.[41] Oxygen affinity in the blood decreases by 0.20 kPa/°C (0.016 psi/°F) at a pH of 7.4.[42] The octopod's thermal tolerance is limited by its ability to consume oxygen, and when it fails to provide enough oxygen to circulate at extreme temperatures the effects can be fatal.[41] O. vulgaris has a pH-independent venous reserve that represents the amount of oxygen that remains bound to the respiratory pigment at constant pressure of oxygen. This reserve allows the octopus to tolerate a wide range of pH related to temperature.[42]
As a temperature conformer,[43] O. vulgaris does not have any specific organ or structure dedicated to heat production or heat exchange. Like all animals, they produce heat as a result of ordinary metabolic processes such as digestion of food,[39] but take no special means to keep their body temperature within a certain range. Their preferred temperature directly reflects the temperature to which they are acclimated.[43] They have an acceptable ambient temperature range of 13–28 °C (55–82 °F),[43] with their optimum for maximum metabolic efficiency being about 20 °C (68 °F).[40]
As ectothermal animals, common octopuses are highly influenced by changes in temperature. All species have a thermal preference where they can function at their basal metabolic rate.[43] The low metabolic rate allows for rapid growth, thus these cephalopods mate as the water becomes closest to the preferential zone. Increasing temperatures cause an increase in oxygen consumption by O. vulgaris.[19] Increased oxygen consumption can be directly related to the metabolic rate, because the breakdown of molecules such as glucose requires an input of oxygen, as explained by the Krebs cycle. The amount of ammonia excreted conversely decreases with increasing temperature.[19] The decrease in ammonia being excreted is also related to the metabolism of the octopus due to its need to spend more energy as the temperature increases. Octopus vulgaris will reduce the amount of ammonia excreted in order to use the excess solutes that it would have otherwise excreted due to the increased metabolic rate. Octopuses do not regulate their internal temperatures until it reaches a threshold where they must begin to regulate to prevent death.[19] The increase in metabolic rate shown with increasing temperatures is likely due to the octopus swimming to shallower or deeper depths to stay within its preferential temperature zone.
Spawning of O. vulgaris in this area extends from December to September with a unique peak in spring months. [44]
The common octopus (Octopus vulgaris) is a mollusc belonging to the class Cephalopoda. Octopus vulgaris is one of the most studied of all octopus species, and also one of the most intelligent. It ranges from the eastern Atlantic, extends from the Mediterranean Sea and the southern coast of England, to the southern coast of South Africa. It also occurs off the Azores, Canary Islands, and Cape Verde Islands. The species is also common in the Western Atlantic.
El pulpo común o pulpo de roca[1] (Octopus vulgaris) es una especie de molusco cefalópodo octópodo de la familia Octopodidae. Vive en el mar Mediterráneo, así como en el Atlántico oriental.
El pulpo común tiene una envergadura de un metro. El manto puede crecer hasta 25 centímetros. En general es de un tono marrón, pero puede cambiar su color de la piel e incluso la textura para mimetizarse con el entorno. Consta de una gran cabeza, de forma ovalada, donde se encuentran varios aparatos del organismo y de 8 brazos o tentáculos, con dos hileras de ventosas cada uno, que pueden regenerarse si son amputados.[2] Bajo los tentáculos se encuentra la boca, en forma de pico. Los ojos, muy desarrollados, se encuentran cerca de los brazos. El sifón, situado en la parte trasera del cuerpo, tiene forma de W.
Se encuentra desde aguas superficiales hasta los 100 metros de profundidad. De actividad principalmente nocturna, es un animal carnívoro, que se alimenta de crustáceos pequeños, bivalvos y peces. Durante el día, sin embargo, permanece oculto en grietas o cavernas. Para desplazarse suele arrastrarse por el fondo ayudándose con sus 8 brazos, aunque también puede nadar, utilizando la propulsión a chorro. Para defenderse expulsan una secreción, a base de tinta, para confundir a su agresor. Su longevidad se estima entre 12 y 18 meses.
En el apareamiento, el macho introduce el esperma en una cavidad del manto de la hembra. Esta pone entre 10 000 y 50 000 huevos, dispuestos en forma de racimos blanquecinos, en lugares protegidos. La hembra cuida de la puesta, batiendo el agua circundante para oxigenarla. Durante este tiempo la hembra no se alimenta, y la mayoría de las veces muere tras la eclosión de los huevos. Al nacer, las crías de pulpo adquieren un modo de vida planctónico que se prolonga hasta casi dos meses, cuando toman el hábito de vivir en el fondo.
El pulpo común se pesca en varias zonas del mundo y se cocina de formas muy diferentes. En la costa del Perú se consume el cebiche de pulpo. En el noroeste de España y en Argentina se prepara el pulpo a la gallega, un plato originalmente consumido en fiestas. Tras su cocción, es servido espolvoreado con pimentón. Se corta en rodajas de 1 cm de grosor, y se le añade aceite de oliva y sal gorda.
El documental Lo que el pulpo me enseñó, sobre la amistad entre un pulpo común salvaje y un cineasta buceador, y filmado en su medio natural a lo largo de casi un año, puso de manifiesto la gran inteligencia del pulpo. Cosechó un amplio éxito en el mundo entero y ganó en 2021 el Óscar al Mejor Largometraje Documental.[3]
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El pulpo común o pulpo de roca (Octopus vulgaris) es una especie de molusco cefalópodo octópodo de la familia Octopodidae. Vive en el mar Mediterráneo, así como en el Atlántico oriental.
See artikkel räägib liigist; perekonna kohta vaata artiklit Kaheksajalg (perekond); sugukonna kohta vaata artiklit Kaheksajalglased; seltsi kohta vaata artiklit Kaheksahaarmelised Harilik kaheksajalg (Octopus vulgaris) on sugukonda kaheksajalglased kuuluv peajalgne; kaheksahaarmeliste seltsi tavalisim ja suurim liik.
Harilik kaheksajala looduslik levila ulatub Suurbritannia lõunarannikust Vahemerd läbides Senegalini Aafrikas. Samuti esineb teda Assooridel, Kanaari saartel ja Roheneemesaartel[1].
Kaheksajala pikkus, arvestades mantlit, on 25 cm ja koos kombitsatega on see kuni 1 m[1].
Harilik kaheksajalg (Octopus vulgaris) on sugukonda kaheksajalglased kuuluv peajalgne; kaheksahaarmeliste seltsi tavalisim ja suurim liik.
Harilik kaheksajala looduslik levila ulatub Suurbritannia lõunarannikust Vahemerd läbides Senegalini Aafrikas. Samuti esineb teda Assooridel, Kanaari saartel ja Roheneemesaartel.
Kaheksajala pikkus, arvestades mantlit, on 25 cm ja koos kombitsatega on see kuni 1 m.
Olagarro arrunta (Octopus vulgaris) olagarro espezie bat da. 100 cm luze izateraino hazten da. Olagarroen artean espezierik ezagunena da, iparraldeko Ozeano Atlantikoan eta Mediterraneo itsasoan bizi dena.[1]
Azal grisa eta orban marroixkakikoa eta garroetan bi bentosa ilara dituena. Itsasazpi harkaiztsuetan bizi da. Soinberak eta oskoldunak jaten ditu, batez ere.[2]
Olagarro arrunta (Octopus vulgaris) olagarro espezie bat da. 100 cm luze izateraino hazten da. Olagarroen artean espezierik ezagunena da, iparraldeko Ozeano Atlantikoan eta Mediterraneo itsasoan bizi dena.
Azal grisa eta orban marroixkakikoa eta garroetan bi bentosa ilara dituena. Itsasazpi harkaiztsuetan bizi da. Soinberak eta oskoldunak jaten ditu, batez ere.
Meritursas (Octopus vulgaris) on maailman merissä laajalle levinnyt suurikokoinen ja kaupallisesti merkittävä mustekalalaji.
Meritursaan pussimainen ruumis on pehmeä ja suojaton, sen keskellä on suuaukko. Suuaukon kitiinileuat muistuttavat nokkaa, ja niitä ympäröi pyöreä huuli. Suun keskellä on riivinrautamainen raastinkieli eli radula. Vaippaontelo muodostuu kiduksia ympäröivästä lihaksikkaasta vaipasta. Tursaan hengitysvesi kulkeutuu vaippaonteloon ja sieltä kiduksiin. Tursaalla on kahdeksan suunnilleen saman mittaista lonkeroa, joissa kussakin on kaksi imukuppiriviä. Pää liittyy välittömästi pussimaiseen ruumiiseen. Pään molemmilla sivuilla on silmät. Rustokoppa suojaa tursaan aivoja. Selkärangattomaksi eläimeksi tursaalla on hyvin kehittynyt hermosto. Aivoissa on jopa 30 eri lohkoa, jotka säätelevät tursaan toimintoja. Meritursas voi oppia erottamaan esineitä ulkomuodon perusteella.
Meritursas on nopeakasvuinen, vuoden vanhana 75 cm:n pituinen. Normaalisti meritursaan paino on n. 1–10 kg. Meritursas on suosittu herkku Japanissa, Italiassa, Espanjassa, Kreikassa ja Tunisiassa. Meritursaita pyydetään kaupallisesti noin 50 000 tonnia vuosittain. Suurimmat pyyntimaat vuonna 1999 olivat Meksiko ja Italia.
Meritursaan puolustuskeino saalistajia vastaan on nopea värinvaihto ja sulautuminen ympäristöön. Vaihdoksen aiheuttavat kromatoforisolut, joita on aikuisella yksilöllä 1–2 miljoonaa eri puolilla ruumista. Keskushermosto säätelee niiden toimintaa. Tämän takia meritursasta on melkeinpä mahdoton havaita pohja-aineksen joukosta. Toinen puolustuskeino on muste, tumma melaniiniväri. Vaaran uhatessa tursas tyhjentää mustesäiliönsä vaippaonteloon ja työntää sen vesisuihkun mukana ulos, jolloin se leviää laajaksi pilveksi. Mustepilven turvin tursas pakenee.
Meritursaat ovat petoja kuten muutkin pääjalkaiset. Ne käyttävät saalistukseen tarkinta aistiaan eli näköä. Tavallisesti tursas odottaa saalistaan liikkumattomana kolossa, kunnes saaliseläin tulee näköpiiriin. Tursas lamauttaa saaliin limarauhasten erittämällä myrkyllä. Se paloittelee saaliinsa radulallaan. Tursas syö myös erilaisia kotiloita, simpukoita, taskurapuja ja muita merenpohjan pikkueläimiä.
Meritursas on levinnyt kaikkiin trooppisiin ja lauhkeisiin meriin. Atlantissa levinneisyys ulottuu Englannin etelä- ja luoteisrannikolta Afrikan rannikolle ja Välimerelle ja Connecticutista Brasiliaan. Elinalue ulottuu rantavyöhykkeestä 200 metrin syvyyteen.
Meritursaat ovat yksineuvoisia. Koiraat ja naaraat tulevat sukukypsiksi eri aikoina. Koiras on jo noin 200-grammaisena sukukypsä, kun taas naaras saavuttaa sukukypsyyden vasta parikiloisena. Meritursaiden lisääntymiskausi on yleensä maalis- ja lokakuun välisenä aikana.
Meritursaat siirtyvät syvistä vesistä parittelemaan rannan läheisyyteen. Lisääntymistä varten koiraan kolmas lonkero muuttuu sekundaariseksi paritteluelimeksi, heterocotylukseksi. Kosiessaan koiras esittelee toisen lonkeroparin alapuolella olevia tavallista suurempia imukuppeja. Parittelussa koiraan spermatoforit eli siittiöitä sisältävät pakkaukset siirtyvät heterocotyluksen alapinnassa olevaa uurretta pitkin naaraan vaippaonteloon.
Naaras laskee 50 000–180 000 läpimitaltaan 3,5-millimetristä munaa, joita se vartioi 3,5–9 viikkoa. Poikasten kuoriuduttua naaras kuolee. Munasta kuoriuduttuaan poikaset uivat kohti valoa ja kulkeutuvat helposti virtojen mukana. 1–3 kuukauden kuluttua toukat vajoavat pohjaan ja etsivät sopivan kolon.
Meritursas (Octopus vulgaris) on maailman merissä laajalle levinnyt suurikokoinen ja kaupallisesti merkittävä mustekalalaji.
Octopus vulgaris
La pieuvre commune ou poulpe commun (Octopus vulgaris) est une espèce de pieuvres de la famille des octopodidés vivant dans les eaux côtières des mers tropicales et subtropicales. C'est l'espèce de pieuvre la plus étudiée, notamment pour son intelligence particulièrement élevée pour un invertébré.
Le manteau de la pieuvre commune mesure jusqu'à 25 cm de longueur, les bras jusqu'à un mètre de long[1]. Son poids à taille adulte avoisine les huit kilogrammes.
La pieuvre a un siphon juste derrière la tête sur un côté de son manteau qu'elle utilise de trois façons : fréquemment pour rejeter l'eau quand ses branchies en ont prélevé l'oxygène ; et occasionnellement soit pour s'enfuir en déchargeant rapidement de l'eau pour se propulser, soit pour jeter un nuage d'encre afin de dérouter l'ennemi[2].
Comme tous les céphalopodes, elle est capable de changer de couleur pour se fondre dans son environnement par homochromie, elle peut ainsi se jeter sur une proie par surprise ou se cacher de la vue de ses prédateurs.
Sa durée de vie est en moyenne de deux ans, car elle meurt après s'être reproduite[3].
Cette espèce a une répartition géographique mondiale[3]. Mais on la trouve en abondance en mer Méditerranée et de la côte sud de l'Angleterre jusqu'au Sénégal, ainsi que dans les eaux littorales japonaises. On la trouve également en abondance aux Açores, aux Canaries et au Cap-Vert[1].
Elle se cache dans les rochers et occasionnellement dans les fonds sableux jusqu'à cent mètres de profondeur. Lorsqu'elle se trouve dans un milieu sablonneux, la pieuvre commune entreprend parfois la construction d'un refuge. Elle transporte et entasse les quelques débris ou pierres qu'elle trouve dans son entourage, à l'aide de ses bras musclés et ses centaines de ventouses, pour former une sorte de tanière dans laquelle elle se tapit[4].
La pieuvre commune se nourrit principalement de crustacés (crabes, homards), de mollusques (gastéropodes et bivalves marins), mais elle mange à peu près tout ce qu'elle peut attraper.
La pieuvre commune chasse au crépuscule, terrée dans les trous et les anfractuosités, où elle guette ses proies. Elle attrape et immobilise sa proie avec une vitesse stupéfiante, à l'aide de ses bras extensibles garnis de deux rangées de ventouses. Le poulpe paralyse ensuite sa proie grâce à une neurotoxine sécrétée par ses glandes salivaires et injectée à l'aide de son bec. Si la victime est un mollusque bivalve, la pieuvre utilise son bec pour percer un trou dans la coque avant de sucer le contenu charnu[4].
Après l’accouplement qui peut durer quelques heures, la femelle pond pendant quinze à trente jours, selon sa taille, de 70 000 à 600 000 œufs d'environ 2,5 mm chacun, rassemblés dans des dizaines de grappes qu'elle fixe à la voûte de sa tanière[5]. Elle les protège et les entretient sans s’occuper d’elle-même ni même se nourrir, l'incubation variant selon la température (20 à 30 jours à 25 °C, 100 à 120 jours à 13 °C)[5]. Elle meurt au bout d’un mois, précédant de quelques semaines le mâle. Le dimorphisme sexuel se caractérise par la transformation d'un des bras du mâle en organe fécondant (hectocotyle)[4].
Le juvénile sort de son œuf en utilisant la propulsion créée par des contractions du manteau, et nage immédiatement en pleine eau pour rejoindre le large. Sa phase planctonique est influencée par la température, allant de trente-trois jours à 25 °C à soixante jours à 21 °C[5].
Comme la plupart des pieuvres, la pieuvre commune a peur des hommes. C'est un animal extrêmement timide et dépourvu d'agressivité. Elle est apprivoisable et ne mord jamais, même si on la provoque[4].
Des expériences d'apprentissage ont montré que la pieuvre commune peut distinguer la luminosité, la taille, la forme et l'orientation verticale ou horizontale des objets.
La pieuvre commune est assez intelligente pour apprendre à dévisser un pot contenant de la nourriture[6], elle est aussi connue pour sa capacité à piller les casiers à homard. C'est le seul invertébré protégé par le 1986 Animals (Scientific Procedures) Act (ASPA) au Royaume-Uni, où ils ont été ajoutés en raison de leur intelligence.
En avril 2016, Inky, une pieuvre commune mâle qui résidait à l'Aquarium national de Nouvelle-Zélande de Napier depuis 2014, est vraisemblablement parvenue à s'échapper de son bassin pour regagner le Pacifique en se faufilant par un petit interstice situé dans le haut de son bassin, à glisser jusqu'au plancher et à trouver l’entrée – minuscule – d’un drain menant à l’océan. Ses gardiens ont repéré au sol des traces gluantes menant au drain, validant ainsi la théorie la plus plausible pour expliquer la disparition du céphalopode de son bassin[7],[8].
La pieuvre commune est une espèce comestible et appréciée de l'être humain. Elle fait depuis longtemps partie du régime alimentaire des populations côtières, car elle y abonde et se capture facilement. Elle est généralement capturée avec un chalut de fond à grande échelle. En 1976, 137 000 tonnes ont été pêchées[3]. Plus de 20 000 tonnes sont récoltées chaque année au large de la côte nord-ouest de l'Afrique[1].
La pieuvre commune s'adapte facilement à la vie en captivité, on la trouve donc dans la plupart des aquariums publics. Elle ne bénéficie pas de mesure de protection internationale, les particuliers peuvent donc en élever.
Le poulpe du documentaire La Sagesse de la pieuvre (My Octopus Teacher), film sud-africain réalisé par Pippa Ehrlich et James Reed, appartient à l’espèce Octopus vulgaris[9]. Le film a obtenu l'Oscar 2021 du meilleur film documentaire.
Pieuvre commune retranchée dans une cavité et laissant apparaître son œil.
Déplacement d'une pieuvre commune.
La pieuvre commune peut se déplacer par propulsion.
Exemplaire à Santander (Espagne).
Pieuvre commune dans le parc naturel de l'Arrábida, Portugal. Juillet 2020.
Autre pieuvre commune dans le parc naturel de l'Arrábida, Portugal. Juillet 2020.
Octopus vulgaris
La pieuvre commune ou poulpe commun (Octopus vulgaris) est une espèce de pieuvres de la famille des octopodidés vivant dans les eaux côtières des mers tropicales et subtropicales. C'est l'espèce de pieuvre la plus étudiée, notamment pour son intelligence particulièrement élevée pour un invertébré.
O polbo común[1] (Octopus vulgaris, Cuvier 1797) é un molusco cefalópodo octópodo, da familia Octopodidae, de grande importancia pesqueira e moi apreciado na gastronomía.
De corpo globoso, superficie rugosa e sen aletas, provisto de oito tentáculos (ou raxos) dotados na cara interna de dúas filas de ventosas cada un, situados ó redor da boca e unidos entre si por unha membrana na base. Os tentáculos frontais (o primeiro par) son máis curtos que os laterais. O terceiro brazo dereito é o brazo hectocotilo, con funcións copuladoras, e ten un ensanchamento no extremo pouco destacado, a modo de culler. Alcanza tamaños de ata 160 cm, incluíndo os tentáculos, que veñen sendo 2-3 veces máis longos que a cabeza, e pesos de ata 14 kg.
A cabeza é grande, ovalada ou arredondada. A boca está provista dun forte pico córneo. Os ollos, moi desenvolvidos. O sifón, na parte traseira do corpo, ten forma de W.
A cor é moi variable, dependendo do estado do animal e da cor e características da contorna na que se agocha, para permitir unha camuflaxe co medio. Normalmente é de cor marrón agrisado, máis ou menos escuro, con manchas irregularmente dispostas de cor verde ou amarela. Poden cambiar voluntariamente a cor da pel e mesmo a textura, imitando as rochas.
Vive en áreas litorais, sempre cerca da costa, sobre fondos rochosos, agochado durante o día en grutas ou entre rochas. É activo de noite e de hábitos carnívoros (crustáceos, moluscos e peixes pequenos).
Péscase con diferentes artes de pesca durante todo o ano, especialmente cunha nasa específica para o polbo. Tradicionalmente se pescaba tamén ao espello dende embarcación, á seca ou con raña. Os caladoiros de Marrocos e as Canarias son especialmente abundantes.
En Galicia, a forma típica de cociñalo é á feira, con aceite de oliva, sal e pemento, pero tamén se consome cociñado doutras formas (con cachelos, en empanada, en caldeirada, encebolado etc.). Constitúe un prato típico de moitas romarías e festas patronais.
Ríos Panisse atopou o castelanismo pulpo con tanta extensión como a forma propia polbo, e Rosa Ramonel matiza que se lle dá o nome de polbo cando está vivo e de pulpo unha vez pescado e, sobre todo, cociñado.
Pode distinguirse do polbo cabezudo mediante a adxectivación polbo da pedra, polbo da costa, polbo da praia, mentres que aquel sería o polbo de altura ou polbo do limpo.
O polbo común (Octopus vulgaris, Cuvier 1797) é un molusco cefalópodo octópodo, da familia Octopodidae, de grande importancia pesqueira e moi apreciado na gastronomía.
Hobotnica (lat. Octopus vulgaris) je vrsta mekušca iz porodice Octopodidae. Ima 8 krakova s kojima može dostići duljinu i do 3 metra. Hobotnica je odlično prilagođena životu lovca, ali i plijena, jer ima tajno oružje. U tjelesnim naborima krije vrećicu s crnilom koje ispušta kad želi zbuniti svoje neprijatelje. Nevjerojatno ljupka hobotnica izgleda kao gomoljasta glava s osam nogu, no njezino vrećasto tijelo krije iznimno dobro razvijen mozak i živčani sustav, zbog čega je hobotnica iznenađujuće inteligentna morska životinja.
Hobotnica je važan stanovnik morskog dna gdje živi na stjenovitim obalama i većinu vremena provodi u rupama ili raspuklinama stijena u plitkoj vodi. Katkad krakovima prenosi kamenje i gradi neku vrstu "utvrde" na morskom dnu. Hobotnica se kreće plivajući ili pužući po dnu na vrhovima krakova, a pri bijegu se kreće unatrag. Po mogućnosti se povlači uvijek u isto sklonište. Sklonište se prepoznaje po uredno naslaganom većem i manjem kamenju ispred rupe. Mužjak se od ženke razlikuje po trećem kraku sa desne strane, gledajući odozgora, koji kod mužjaka završava u obliku žličice, zove se hektokotilus.
Danju hobotnica većinu vremena provodi u svom skrovištu i pritom promatra okolinu. Njezine velike oči s kapcima prilagođene su prigušenom svjetlu pod vodom pa mogu razaznati gibanja i prepoznati strukture.
Hobotnica je osjetljiva na hladnoću i zbog toga ih mnogo ugiba zimi u plitkim predjelima uz obalu zbog niskih temperatura mora. Hobotnica zamočena u slatku vodu ugiba za nekoliko sekundi.
Kao većina podvodnih lovaca izlazi i hobotnica iz svojeg skrovišta tek kad se smrači te odlazi u potragu za hranom. Njezina omiljena hrana su rakovi, rakovice i školjkaši. Iako je hobotnica odličan plivač, najčešće svoj plijen lovi primjenjujući lukavstvo. Može mijenjati boju tijela i tako se prilagoditi okolini. Ležeći maskirana na morskom dnu promatrat će okolinu i jurnuti na neopreznog "prolaznika" te ga omamiti svojim nervnim otrovom. Njezini dugi i snažni krakovi rastezljivi su i opremljeni s dva reda prianjalki, kojima hobotnica može čvrsto držati i sklizak plijen.
Ako je njezina žrtva neki mekušac s tvrdom ljušturom, hobotnica će razbiti ljušturu svojim "papagajskim kljunom" tj. čeljustima sličnim kljunu. Kad želi uloviti neki mnogo opasniji plijen, kao što je naprimjer hlap, služi se lukavijom metodom. Najprije u vodu ispusti oblak crnila i tako smanji vidljivost, a zatom se kroz taj oblak oprezno približi hlapu i zgrabi ga sa stražnje strane kako ovaj ne bi mogao upotrijebiti svoja kliješta za obranu.
U neprijatelje hobotnice ubrajaju se ugori, dupini i morski psi, kojima je ona česta hrana. Ako je moguće, hobotnica će im pobjeći najvećom mogućom brzinom pomoću svog "mlaznog pogona" te izbaciti crnilo. Hobotnica osim toga ima sposobnost da se provuče kroz vrlo male otvore kroz koje je neprijatelji ne mogu slijediti pa ostaju zbunjeni ispred njenog skloništa.
Svojom sposobnošću da se bojom u potpunosti prilagodi okolini hobotnica, međutim, već unaprijed sprečava da je netko otkrije. Ona pigmente boje u svojoj koži može rasporediti po želji, može ih na nekim mjestima zgusnuti, na nekima razrijediti te oblikovati pruge i uzorke koji su u skladu s okolinom.
Najučinkovitija obrambena metoda jest ona ista koju koristi i u lovu. Ako je netko slijedi, ispustit će hobotnica u vodu velik oblak crnila. Istodobno ispušta i tvar koja umrtvljuje osjetilo mirisa protivnika tako da je on više neće biti u stanju pronaći.
Mora se spomenuti i 'otrovni zub' koji se nalazi u središtu gdje izrastaju krakovi, ispod hobotnice. Ribolovci paze da taj zub uklone kada ulove hobotnicu da ne nastradaju.
Hobotnice koje se pare izgledaju kao da se drže za ruke. No u stvarnosti mužjak pomoću posebnog kraka, koji se naziva hektokotilus, uštrcava spermafore (sjemene vrećice) u otvor plašta ženke kako bi oplodio jajašca. Tjedan dana kasnije ženka polaže jajašca u obliku grozdastih nakupina, oblaže ih želetinoznom masom i pričvršćuje za stijenu. Tijekom četiri do šest tjedana, koliko je potrebno da se iz jaja izlegu larve, čuva jajašca, često ih dodiruje i čisti te im dovodi svježu vodu. Ta briga za mrijest može je stajati i života jer za to vrijeme ništa ne jede pa može u potpunosti izgubiti snagu i uginuti.
Iz jaja će se izleći ličinke duge samo 3 mm,koje izgledaju kao minijaturne hobotnice. Zajedno s planktonom plutaju neko vrijeme u vodi da bi se kasnije spustile na morsko dno, gdje brzo rastu.
Hobotnica (lat. Octopus vulgaris) je vrsta mekušca iz porodice Octopodidae. Ima 8 krakova s kojima može dostići duljinu i do 3 metra. Hobotnica je odlično prilagođena životu lovca, ali i plijena, jer ima tajno oružje. U tjelesnim naborima krije vrećicu s crnilom koje ispušta kad želi zbuniti svoje neprijatelje. Nevjerojatno ljupka hobotnica izgleda kao gomoljasta glava s osam nogu, no njezino vrećasto tijelo krije iznimno dobro razvijen mozak i živčani sustav, zbog čega je hobotnica iznenađujuće inteligentna morska životinja.
Il polpo comune[2] (Octopus vulgaris Cuvier, 1797) o piovra[3] è un mollusco cefalopode della famiglia Octopodidae. Nell'uso comune viene impropriamente chiamato anche polipo,[4] termine che in realtà in zoologia spetta solo agli stadi vitali fissi del phylum celenterati, come quelli dei coralli.
Il termine polpo ha origine dal latino pōlypus, da una forma greca dorica πώλυπους (pṓlypous) o πωλύπους (pōlýpous),[5] in attico πολύπους (polýpous), probabilmente da πολύς (polýs), "molto", e πούς, (póus), "piede", quindi "dai molti piedi".[6]
Il termine piovra deriva da pieuvre, forma dialettale normanna derivante dal latino pōlypus.[7]
Spesso ci si riferisce al polpo utilizzando la parola polipo, ma il nome zoologicamente corretto è polpo, in quanto i polipi sono invece animali acquatici (o una forma di essi) appartenenti al phylum degli Cnidari[8].
È un mollusco cefalopode molto diffuso nei bassi fondali, non oltre i 200 metri. Preferisce i substrati aspri, rocciosi, perché ricchi di nascondigli, fessure e piccole caverne in cui nascondersi: l'assenza di endo- ed esoscheletro gli permette di prendere qualsiasi forma, e di passare attraverso cunicoli molto stretti. Presente in tutti i mari e gli oceani, è molto diffuso anche nel Mar Mediterraneo. Nel Mediterraneo viene pescato principalmente in due diversi periodi dell'anno: da settembre a dicembre (in buone quantità, seppur ancora di piccola taglia) e da maggio a luglio (periodo nel quale è di taglia più grossa).
Il polpo possiede 3 cuori e ha la capacità di cambiare colore molto velocemente e con grande precisione nel dettaglio. Sfrutta questa abilità sia per mutare affinché non sia visto dai predatori, sia per comunicare con i suoi simili. Caratteristica principale è la presenza di una doppia fila di ventose su ognuna delle otto braccia, il che lo distingue dal moscardino che ha una sola fila di ventose. Al centro degli otto tentacoli, sulla parte inferiore dell'animale, si trova la bocca che termina con un becco corneo utilizzato per rompere gusci di conchiglie e il carapace dei crostacei dei quali si nutre. Il manto è lungo 8–25 cm[9], i tentacoli invece sono lunghi in media 40–100 cm, il peso varia da 500 grammi fino a 7–8 kg degli esemplari più grandi. In genere i maschi sono più grandi delle femmine. L'Octopus vulgaris vive mediamente un anno, massimo un anno e mezzo. Altre specie, come la piovra gigante del Pacifico (Enteroctopus dofleinii) hanno aspettativa di vita maggiore, sopravvivendo anche 5-6 anni.
Può spostarsi rapidamente espellendo con forza l'acqua attraverso un sifone, che viene utilizzato anche per l'emissione dell'inchiostro nero usato in funzione difensiva per confondere possibili predatori. Il nero assolve alla duplice funzione di creare una barriera visiva tra sé e il predatore e a confondere l'olfatto di quest'ultimo, essendo ricco di ormoni.
Per attrarre le femmine, i polpi effettuano un rituale di corteggiamento. Liberano sperma in pacchetti seminali, detti spermatofore. Per trasferirli alla cavità palleale della femmina durante la copula, utilizzano un braccio modificato chiamato ectocotilo. Dopo che la femmina del polpo ha deposto le uova (in numero che varia da 50.000 a 400.000) le difende da possibili predatori fino alla schiusa. In questo periodo di 1-2 mesi non si nutre perdendo una gran parte del suo peso e muore dopo la schiusa. Le paralarve che escono dalle uova attraversano prima una fase planctonica, per poi subire metamorfosi, diventare bentonici, ed essere in tutto e per tutto simili ad adulti in miniatura.
Il polpo è talvolta confuso con la polpessa (Callistoctopus macropus), un cefalopode dalle abitudini notturne, caratterizzato da una livrea rossiccia e punteggiata di bianco, meno robusto e con tentacoli più lunghi del polpo che talvolta gli permettono di predare anche il polpo stesso.
È considerato uno degli invertebrati più intelligenti; è stato, per esempio, dimostrato che il polpo comune ha la capacità di apprendere se sottoposto a test di apprendimento per associazione e osservando gli altri della sua specie, capacità che era stata dimostrata solo in alcuni mammiferi. Quest'ultima evidenza è alquanto sorprendente, poiché, essendo il polpo un animale fortemente solitario, sembrerebbe inspiegabile un comportamento simile, tipico di animali con rapporti sociali.
Una volta pescato, è in grado di riguadagnare la libertà uscendo attraverso i boccaporti delle navi. Sottoposto a test durante i quali gli è stata somministrata una preda rinchiusa in un barattolo, il polpo ha dimostrato di essere in grado di aprire il barattolo per raggiungere il cibo.
Talora usa acquattarsi sotto gli anfratti rocciosi del fondo marino. In altri casi vive in tane preparate con pietre e conchiglie disposte in circolo, a difesa dell'imboccatura.
Nonostante il polpo sia uno degli invertebrati più intelligenti, non sono stati condotti molti studi con loro nel campo del dolore. Secondo una nuova ricerca, i polpi provano dolore psicologico allo stesso modo dei mammiferi.[10]
Nel 2015, due gruppi di ricerca, all'Università di Chicago e all'Università della California a Berkeley, hanno compiuto il sequenziamento del genoma del polpo e di vari trascrittomi, operazione che ne ha rivelato le notevoli peculiarità[11][12]. Si tratta, infatti, di un genoma più ampio di quello umano e con un numero superiore di geni codificanti (circa 33.000, contro i 25.000 del genoma umano). La vastità del genoma è dovuta, in massima parte, all'espansione di due famiglie di geni, le protocaderine e i fattori di trascrizione C2H2.
I geni codificanti per le protocaderine sono presenti in misura doppia rispetto ai mammiferi: trattandosi di proteine implicate nello sviluppo neurale, l'espansione della famiglia dei relativi geni codificanti dà conto dell'ampiezza della loro rete neurale che, oltre a costituire il sistema nervoso più sviluppato tra gli invertebrati, contiene sei volte il numero di neuroni del topo. Due terzi dei neuroni del polpo, peraltro, sono direttamente collegati agli organi di movimento (al punto che i tentacoli possono svolgere funzioni cognitive perfino da recisi: ad esempio, una volta recisi sono ancora in grado di riconoscere come sé il resto del corpo[13]).
Altra particolarità è stata evidenziata con l'individuazione di un gruppo di proteine coinvolte nello spiccato mimetismo del cefalopode, le reflectine, in grado di alterare le modalità di riflessione ottica della luce che incide sul corpo del polpo.
Inoltre, lo studio del genoma ha permesso la scoperta di un meccanismo che consente alle cellule di cambiare in modo rapido le funzioni di proteine già codificate, intervenendo con modifiche sulle stesse. Gli scienziati ipotizzano che questo meccanismo abbia a che vedere con le eccezionali attitudini all'apprendimento esibite da questi cefalopodi.
Il polpo è un mollusco molto ambito nella pesca di professione con tecniche a strascico o reti da posta, ma anche sportiva e le tecniche di pesca sono tradizionali consistono nell'utilizzo di un'esca chiamata polpara che talvolta viene utilizzata insieme a granchi e pesci. Talvolta il polpo fresco viene preparato con la tecnica prima dello "sbattimento" poi dell'arricciatura direttamente sugli scogli o in macchine apposite che ne consentono la degustazione a crudo. Il polpo arricciato si presenta con i tentacoli a forma di “boccoli”, le ventose dilatate ed ha una caratteristica consistenza "croccante".
Per le sue carni gustose è utilizzato nelle cucine di molti paesi. Viene consumato principalmente bollito e successivamente condito in molteplici modi, ma anche arrostito, fritto e in tegame.
Il polpo comune ha probabilmente dato vita alla figura del leggendario Kraken, che, secondo la mitologia norrena, era un gigantesco polpo (o calamaro, secondo altri), che affondava le navi di passaggio.
Per similitudine si designa come piovra la "persona avida e priva di scrupoli, che vive sfruttando egoisticamente e spietatamente un’altra o altre persone, fino a distruggerne le risorse e le energie, e a provocarne talvolta la rovina"[14]; con "allusione non solo ai lunghi e forti tentacoli del mollusco ma anche alla sua vita abissale (...) è oggi una metafora corrente con cui è indicata soprattutto la mafia, per influenza del titolo («La piovra») della omonima serie televisiva"[15].
Il polpo comune (Octopus vulgaris Cuvier, 1797) o piovra è un mollusco cefalopode della famiglia Octopodidae. Nell'uso comune viene impropriamente chiamato anche polipo, termine che in realtà in zoologia spetta solo agli stadi vitali fissi del phylum celenterati, come quelli dei coralli.
Paprastasis aštuonkojis (Octopus vulgaris) – aštuonkojų būrio bestuburis gyvūnas.
Paplitęs Atlanto vandenyne, Viduržemio ir Karibų jūrose. Užauga iki 90 cm ilgio. Gyvena jūros dugne tarp akmenų. Dauginasi dėdamas kiaušinius, kuriuos saugo patelė. Tuo metu ji niekuo neminta, o maždaug po 6 savaičių, išsiperėjus jaunikliams, miršta. Tai vienas protingiausių bestuburių gyvūnų. Krabus ir kitus nedidelius gyvūnus iš urvų bei plyšių išsitraukia savo čiuptuvais.
Parastais astoņkājis jeb vienkārši astoņkājis (Octopus vulgaris) ir astoņkāju dzimtas (Octopodidae) suga, kas ir visvairāk pētītā astoņkāju suga pasaulē.
Astoņkāja dabīgais izplatības areāls ietver Vidusjūru, Atlantijas okeāna abus krastus, Indijas okeāna krasta līnija un Klusā okeāna Āzijas krastu.[1] Rietumos ziemeļu robeža atrodas pie Britu salām. Tas sastopams Azoru, Kanāriju un Kaboverdes salu krastos.[2] Austrumos pie Amerikas krastiem izplatības areāls starp ziemeļu un dienvidu robežām nav tik plašs kā rietumos.[1]
Astoņkāji plaši izmanto cilvēku pārtikā. Katru gadu nozvejo 20 000—100 000 tonnas.[3]
Astoņkājim ir mīksts ķermenis bez iekšējā un ārējā skeleta. Tēviņa ķermeņa kopējais izmērs nepārsniedz 1,3 metrus, bet mātītēm 1,2 metrus,[1] taustekļi ir apmēram 1 metru gari.[1] Uz taustekļiem ir 2 rindas ar piesūcekņiem. Tas spēj mainīt ādas krāsu, to meistarīgi piemērojot apkārtējai videi. Astoņkāji zem ūdens vieglāk atrast, meklējot krabju un vēžu čaulas, kas parasti mētājas turpat tuvumā.
Eksperimentos ir noskaidrots, ka astoņkājis spēj atšķirt krāsu spilgtumu, priekšmetu izmērus un formu, kā arī izprot priekšmeta novietojumu telpā (horizontāli vai vertikāli). Tie ir pietiekami inteliģenti, lai iemācītos atskrūvēt burkai vāku,[4] vai pārbaudītu cilvēku izliktās omāru lamatas.[5]
Astoņkājis mājo seklos piekrastos ūdeņos un atklātā jūrā līdz 200 metru dziļumam. Tam patīk akmeņaina grunts, bagāta ar zemūdens klintīm, koraļļu rifi un ūdens zālēm noauguši klajumi. Ja ūdens kļūst vēsāks par 7° C, astoņkājis kļūst lēns un mazaktīvs.[1] Visā izplatības areālā tam ir raksturīga sezoniāla migrācija. Ziemas periodā astoņkājis mājo dziļākos ūdeņos, bet vasarā seklākos.[1]
Astoņkājis ir plēsīgs dzīvnieks un medīt dodas krēslas stundās, bet daļa astoņkāju medī arī dienas laikā.[3] Medījot tas izmanto savus garos, spēcīgos taustekļus. Tas barojas ar krabjiem, vēžiem un citiem jūras dzīvniekiem, ko tas var noķert. Noķerto medījumu astoņkājis vispirms paralizē ar savām indīgajām siekalām. Ja medījums ir gliemis čaulā, tad čaulā vispirms tiek iekniebts caurums, pa kuru mīkstais saturs tiek izsūkts laukā.
Astoņkājis dzīvo 12—18 mēnešus. Mātīte seklos ūdeņos, kādā labi slēptā vietā izdēj 100 000—500 000 rīsa lieluma olas, par kurām tā ļoti rūpējas. Olas ir it kā savērtas uz aukliņas, veidojot vīnogu ķekaram līdzīgu formu. Olu ķekars tiek piestiprināts pie klinšu sienām vai alu griestiem. Māte ar taustekļiem atgaiņā garām peldošās zivis, sakuļ ūdeni, lai apskalotu un piegādātu ar skābekli bagātāku ūdeni. Mazie astoņkāji izšķiļas apmēram pēc 25—65 dienām. Visu šo laiku mātīte nemedī un olas nepamet ne uz mirkli. Lielākā daļa mātīšu pēc tam drīz nomirst.[1] Pēc izšķilšanās mazie astoņkājīši pirmās 45—60 dienas pavada kā planktons. Šajā laikā lielākā daļa kļūst par barību citiem jūras dzīvniekiem. Tie, kas izdzīvo, meklē sev mājvietu jūras dibenā starp akmeņiem un klinšu spraugām.[3]
Parastais astoņkājis jeb vienkārši astoņkājis (Octopus vulgaris) ir astoņkāju dzimtas (Octopodidae) suga, kas ir visvairāk pētītā astoņkāju suga pasaulē.
Astoņkāja dabīgais izplatības areāls ietver Vidusjūru, Atlantijas okeāna abus krastus, Indijas okeāna krasta līnija un Klusā okeāna Āzijas krastu. Rietumos ziemeļu robeža atrodas pie Britu salām. Tas sastopams Azoru, Kanāriju un Kaboverdes salu krastos. Austrumos pie Amerikas krastiem izplatības areāls starp ziemeļu un dienvidu robežām nav tik plašs kā rietumos.
Astoņkāji plaši izmanto cilvēku pārtikā. Katru gadu nozvejo 20 000—100 000 tonnas.
De (gewone) achtarm (Octopus vulgaris), ook wel kraak of gewone octopus genoemd, is een inktvis zonder (inwendig) skelet. Vermoedelijk bestaat deze soort uit een aantal sterk verwante zustersoorten, die moeilijk van elkaar te onderscheiden zijn. Taxonomen zijn het er echter nog niet over eens hoe de soort precies kan worden opgesplitst.[1][2]
Opvallend is de grote kop met de hoogontwikkelde, spleetvormige ogen. Ze hebben een rond, zakvormig lichaam. Ze missen de twee lange vangtentakels en elk spoor van een inwendige schelp. De lange armen zijn bezet met 2 rijen zuignappen.
De achtarm leeft solitair en komt voor op (rotsige) koraalriffen, op zandbodems of op zeegrasvelden tot op diepten van 100 meter (mogelijk zelfs tot 300 meter diepte bij een bepaalde zustersoort). Het dier jaagt vooral 's nachts en leeft van schaaldieren, schelpdieren en vissen.[1] Zelf vormt hij een prooi voor talloze dieren, waaronder zeebaarzen en murenen. Zijn schuilplaats, soms 'octopusburcht' genoemd, is vaak omgeven met stenen en schelpen, die het dier zelf bij elkaar zoekt. Het dier kan zich snel verplaatsen door water uit een pijpvormig orgaan (de sifon) te pompen. Bij dreigend gevaar ledigt hij zijn inktzak, mogelijk om achtervolgers in de war te brengen.
De achtarm komt voor in de Grote Oceaan, de Indische Oceaan en in de Atlantische Oceaan. De grootte van de achtarm varieert van potentiële zustersoort tot zustersoort. De zustersoort die ook in de Noordzee voorkomt kan een lichaam hebben van 25 cm grootte en armen tot 1 meter lang, en is daarmee de grootste.[1]
Het vrouwtje zet haar eitjes af in lange, geleiachtige rijen in grotten en spleten en bewaakt ze ook. Ze voorziet het legsel van vers water via haar bek, reinigt en streelt ze en laat de pasgeboren jongen ten minste een maand niet alleen.
Het dier kan zijn kleur en huid aanpassen aan de kleur en vorm van de achtergrond, teneinde niet op te vallen. De kleurverandering heeft vermoedelijk ook een functie als communicatiemiddel met soortgenoten.
Mediabestanden die bij dit onderwerp horen, zijn te vinden op de pagina Octopus vulgaris op Wikimedia Commons. De (gewone) achtarm (Octopus vulgaris), ook wel kraak of gewone octopus genoemd, is een inktvis zonder (inwendig) skelet. Vermoedelijk bestaat deze soort uit een aantal sterk verwante zustersoorten, die moeilijk van elkaar te onderscheiden zijn. Taxonomen zijn het er echter nog niet over eens hoe de soort precies kan worden opgesplitst.
Multimedia w Wikimedia Commons Ośmiornica zwyczajna, ośmiornica pospolita (Octopus vulgaris) – gatunek głowonoga z rzędu ośmiornic, poławiany komercyjnie na dużą skalę.
Zwierzę zjada raki, kraby, małże i ryby i inne małe organizmy. Ofiary chwyta ramionami, obezwładnia jadem, a następnie rozdrabnia rogowymi szczękami, przypominającymi papuzi dziób.
Ośmiornice są samotnikami, lecz podczas godów samce poszukują partnerek. Gdy napotkają inną ośmiornicę, zaciekle z nią walczą. Spotkanie z samicą zwykle tak nie przebiega (chyba że ma ona wkrótce złożyć jaja). Podczas godów ośmiornice zmieniają zabarwienie[2].
Zwierzęta te pływają przy dnie morza. Kryją się w szczelinach skalnych. "Krocząc" po dnie, poruszają się na wszystkich ramionach[2]. Jak inne ośmiornice, posiada lejek, dzięki któremu może poruszać się ze znaczną prędkością (zwierzę łączy wtedy ramiona, przez co przypomina torpedę).
Zamieszkuje Morze Karaibskie oraz wody przybrzeżne Ameryki Południowej. Żyje także w wodach szelfu kontynentalnego Afryki i Indonezji, całe Morze Śródziemne oraz kanał La Manche.
Ośmiornica zwyczajna, ośmiornica pospolita (Octopus vulgaris) – gatunek głowonoga z rzędu ośmiornic, poławiany komercyjnie na dużą skalę.
O polvo-comum (Octopus vulgaris) é a mais estudada de todas as espécies de polvo. Seu habitat estende-se do Mar Mediterrâneo e da costa sul da Inglaterra até o litoral do Senegal. Também ocorre nos Açores, Ilhas Canárias e em cabo Verde.[1][2]
Um Octopus vulgaris, chamado de Paul, foi uma das sensações da Copa do Mundo FIFA de 2010 ao fazer "previsões" corretas dos resultados dos jogos do campeonato mundial, em especial dos jogos da Seleção Alemã.[3]
O polvo-comum (Octopus vulgaris) é a mais estudada de todas as espécies de polvo. Seu habitat estende-se do Mar Mediterrâneo e da costa sul da Inglaterra até o litoral do Senegal. Também ocorre nos Açores, Ilhas Canárias e em cabo Verde.
Bayağı ahtapot (Octopus vulgaris), kafadan bacaklılar sınıfına ait bir yumuşakçadır. Octopus vulgaris, tüm ahtapot türleri arasında üzerinde en çok çalışma yapılan türdür.
Octopus vulgaris, kozmopolit olarak kabul edilir. Küresel bir tür olarak[1] Akdeniz ile İngiltere'nin güney kıyılarından Doğu Atlantik'e ve Afrika'da en azından Senegal'e kadar bir alana yayılmaktadır. Ayrıca Azor Adaları, Kanarya Adaları ve Yeşil Burun Adaları'nda da bulunur.[2] Bu tür Batı Atlantik'te de yaygındır.[3]
Bayağı ahtapot (Octopus vulgaris), kafadan bacaklılar sınıfına ait bir yumuşakçadır. Octopus vulgaris, tüm ahtapot türleri arasında üzerinde en çok çalışma yapılan türdür.
Bạch tuộc thông thường (danh pháp hai phần: Octopus vulgaris) là một loài bạch tuộc, đây là loài bạch tuộc được nghiên cứu nhiều nhất. Loài này có phjm vi phân bố ở Đông Đại Tây Dương kéo dài từ biển Địa Trung Hải và bờ biển phía nam của nước Anh ít nhất là Senegal ở châu Phi. Nó cũng hiện diện ở Azores, quần đảo Canary, và quần đảo Cabo Verde[1]. Loài này cũng phổ biến ở Tây Đại Tây Dương. Bạch tuộc thông thường dài có lớp áo dài đến 25 cm với cánh tay dài 1m. Bạch tuộc thông thường bị đánh bắt bằng lưới cào đáy trên một quy mô lớn ngoài khơi bờ biển phía tây bắc của châu Phi. Hơn 20.000 tấn được thu hoạch hàng năm.
Bạch tuộc thường săn mồi vào lúc hoàng hôn. Cua, tôm càng, và các động vật thân mềm hai mảnh vỏ (động vật thân mềm hai vỏ như sò) được ưa thích, mặc dù bạch tuộc cũng ăn hầu như bất cứ loài mồi gì nó có thể bắt. Nó có thể thay đổi màu sắc để phù hợp với môi trường xung quanh của nó, và có thể nhảy khi có con mồi không thận trọng mà đi lạc trên đường đi của nó. Con mồi bị tê liệt bởi một chất độc thần kinh do loài bạch tuộc này tiết ra, bạch tuộc có thể nắm bắt con mồi của nó bằng cách sử dụng cánh tay mạnh mẽ của nó với hai hàng giác hút. Nếu nạn nhân là một động vật thân mềm có vỏ, bạch tuộc sử dụng cái mỏ của nó ra một cái lỗ trong vỏ trước khi hút thịt ra[cần dẫn nguồn]. Thí nghiệm huấn luyện đã chỉ ra rằng bạch tuộc thông thường có thể phân biệt độ sáng, kích thước, hình dạng, và định hướng nằm ngang hoặc thẳng đứng của các đồ vật. Chúng có đủ trí thông minh để tìm hiểu làm thế nào để tháo ốc nơi một cái lọ và biết bẫy tôm hùm[2][3].
Bạch tuộc thông thường (danh pháp hai phần: Octopus vulgaris) là một loài bạch tuộc, đây là loài bạch tuộc được nghiên cứu nhiều nhất. Loài này có phjm vi phân bố ở Đông Đại Tây Dương kéo dài từ biển Địa Trung Hải và bờ biển phía nam của nước Anh ít nhất là Senegal ở châu Phi. Nó cũng hiện diện ở Azores, quần đảo Canary, và quần đảo Cabo Verde. Loài này cũng phổ biến ở Tây Đại Tây Dương. Bạch tuộc thông thường dài có lớp áo dài đến 25 cm với cánh tay dài 1m. Bạch tuộc thông thường bị đánh bắt bằng lưới cào đáy trên một quy mô lớn ngoài khơi bờ biển phía tây bắc của châu Phi. Hơn 20.000 tấn được thu hoạch hàng năm.
Bạch tuộc thường săn mồi vào lúc hoàng hôn. Cua, tôm càng, và các động vật thân mềm hai mảnh vỏ (động vật thân mềm hai vỏ như sò) được ưa thích, mặc dù bạch tuộc cũng ăn hầu như bất cứ loài mồi gì nó có thể bắt. Nó có thể thay đổi màu sắc để phù hợp với môi trường xung quanh của nó, và có thể nhảy khi có con mồi không thận trọng mà đi lạc trên đường đi của nó. Con mồi bị tê liệt bởi một chất độc thần kinh do loài bạch tuộc này tiết ra, bạch tuộc có thể nắm bắt con mồi của nó bằng cách sử dụng cánh tay mạnh mẽ của nó với hai hàng giác hút. Nếu nạn nhân là một động vật thân mềm có vỏ, bạch tuộc sử dụng cái mỏ của nó ra một cái lỗ trong vỏ trước khi hút thịt ra[cần dẫn nguồn]. Thí nghiệm huấn luyện đã chỉ ra rằng bạch tuộc thông thường có thể phân biệt độ sáng, kích thước, hình dạng, và định hướng nằm ngang hoặc thẳng đứng của các đồ vật. Chúng có đủ trí thông minh để tìm hiểu làm thế nào để tháo ốc nơi một cái lọ và biết bẫy tôm hùm.
Осьминог обыкновенный (лат. Octopus vulgaris) — один из самых распространённых и хорошо изученных видов осьминогов. Распространён в Средиземном море и в Атлантическом океане от побережья Англии до берегов Сенегала.
Длина тела осьминога обыкновенного достигает 25 см. Руки-щупальца гораздо длиннее — 90 см, но могут достигать и 120—130 см. Вес тела до 10 кг.
Рот осьминога несёт две мощные челюсти, напоминающие клюв попугая. В глотке находится тёрка, позволяющая перетирать пищу. Он обладает восемью щупальцами, снабжёнными многочисленными присосками. У самцов одна из рук преобразуется в совокупительный орган — гектокотиль. У осьминога хорошо развито зрение. Глаза крупные, по строению напоминают глаза позвоночных животных. Головной мозг осьминога достаточно высокоразвит, имеет зачаточную кору. Нервная система осьминога содержит около 500 млн клеток. Это больше, чем у крысы и почти как в головном мозгу кошки[1]. Осьминоги обладают самым высоким интеллектом среди всех беспозвоночных, имеют хорошую память, различают геометрические фигуры, хорошо поддаются дрессировке. Осьминоги различают людей, способны решать нестандартные задачи[1]. Кровеносная система близка к замкнутой: во многих местах артерии переходят в вены через капиллярную систему. У осьминога три сердца: главное находится в полости тела, два других — жаберные. Кровь голубого цвета, так как содержит гемоцианин в качестве дыхательного пигмента.
Осьминог способен изменять окраску тела, приспосабливаясь к среде. В его коже имеются клетки с различными пигментами, способные растягиваться или сжиматься в зависимости от восприятия органов чувств. Типичный окрас — коричневый.
Осьминог обитает на мелководьях, до глубины 100—150 м. Предпочитает скалистые участки дна. Одиночный, территориальный вид. Днём осьминог мало активен, охотится, как правило, в сумерках и ночью. Осьминог — типичный хищник-засадчик. В его рацион входят моллюски, ракообразные, рыба, планктон. Добычу захватывает руками, затем подтягивает её к рту и кусает клювом жертву. При этом яд слюнных желез осьминога попадает в рану. Враги осьминога — дельфины, морские львы, киты, олуши, хищные рыбы.
Размножение происходит дважды в год, как правило, весной и осенью. После спаривания самка устраивает гнездо на мелководье, где откладывает около 80 тысяч яиц[2][3]. Самка ухаживает за яйцами, постоянно вентилирует их, убирает грязь и посторонние предметы. Инкубация продолжается до 4—5 месяцев, в зависимости от температуры воды. В течение всего периода развития яиц самка находится у гнезда, охраняет его, не питается и погибает от истощения при вылуплении личинок[3].
Новорождённые личинки первые 2 месяца питаются планктоном и сами ведут планктонный образ жизни. В возрасте около двух месяцев происходит метаморфоз, личинка превращается в взрослую форму и переходит к придонному образу жизни, типичному для вида. Растут быстро, в возрасте 4 месяцев достигают веса в 1 килограмм. Продолжительность жизни 1—2 года, редко до 4 лет.
Осьминог — важный объект промысла, употребляется человеком в пищу. Мировой вылов осьминога составляет около 40 000 тонн ежегодно, основная масса добывается в Мексике и Италии[4].
Осьминог обыкновенный (лат. Octopus vulgaris) — один из самых распространённых и хорошо изученных видов осьминогов. Распространён в Средиземном море и в Атлантическом океане от побережья Англии до берегов Сенегала.
真蛸（Octopus vulgaris），是屬於章魚科章魚屬的頭足動物。在世界各地的熱帶和溫帶海域皆有分佈[1]，人們經常說的普通八爪魚（普通章魚）就是指這個品種。
外套膜長度可達25釐米，體長（包括觸手）可達一米[2]，觸手的長度約是軀體（所謂的「頭」）的3倍，不過軀體可以自由伸縮。身體表面的疣密生，皮膚色素細胞全身分佈。能隨周圍環境變更體色和身體長度，在岩石和海藻中表現出很好的擬態。
分類 界 : 動物界 Animalia 門 : 軟体動物門 Mollusca 綱 : 頭足綱 Cephalopoda 上目 : 八腕形上目 Octopodiformes 目 : タコ目(八腕目) Octopoda 亜目 : マダコ亜目 Incirrina 科 : マダコ科 Octopodidae 亜科 : マダコ亜科 Octopodinae 属 : マダコ属 Octopus 亜属 : マダコ亜属 Octopus 種 : マダコ O.(O.)vulgaris 学名 Octopus (Octopus) vulgarisマダコ（真蛸、Octopus vulgaris） は、タコ目・マダコ科に属するタコの一種。世界各地の熱帯・温帯海域に広く分布し、日本では一般にタコといえば本種を指すことが多い。
腕を含めた体長は約60cmで、腕は胴体（いわゆる「頭」）の約3倍の長さだが、体はしなやかである程度伸縮する。体表は低い突起が密生し、さらに皮膚には色素細胞がくまなく分布する。周囲の環境に合わせて体色や突起の長さを数秒ほどで変えることができ、岩石や海藻によく擬態する。無脊椎動物の中では特に知能の高い種だと考えられている[1]。
浅い海の岩礁やサンゴ礁に生息するが、外洋に面した海域に多く、内湾には少ない。真水を嫌い、汽水域には生息しない。昼は海底の岩穴や岩の割れ目にひそみ、夜に活動して甲殻類や二枚貝を食べる。腕で獲物を絡め捕り、毒性を含む唾液を注入して獲物を麻痺させ、腕の吸盤で硬い殻もこじ開けて食べてしまう。ヒトに対してもかなりの毒性を発揮し、咬まれた場合相当な期間、痛みが続くことがある。
天敵は人間の他にも海鳥、ウツボ、沿岸性のサメ、エイなどがいる。危険を感じると墨を吐き、敵の視覚や嗅覚をくらませる。腕を自切することもでき、欠けた腕はしばらくすると元通りに再生する[1]。
繁殖期は春から初夏で、交尾したメスは岩陰に潜み、長径2.5mmほどの楕円形の卵を数万-十数万個も産む。マダコの卵は房状にかたまり、フジの花のように見えることから海藤花（かいとうげ）とも呼ばれる。メスは孵化するまで餌を摂らずに卵の下に留まり、漏斗で海水を吹きつけたり、卵を狙う魚などを追い払ったりして卵の世話をする。卵は1ヶ月ほどで孵化するが、メスは孵化を見届けた直後にほとんど死んでしまう。
孵化直後の子ダコは体はほぼ透明で、胴体部分が体の大部分を占めるが、体には色素胞があり、腕に吸盤もある。子ダコは海流に乗って分布を広げるが、この間に多くが他の生物に捕食される。
海底に定着した後は2-3年ほどで急激に成長し、繁殖して寿命を終える。
白いものを餌と認識するようで、ラッキョウを餌にして釣りをする。ミカンの栽培が盛んな地域では、海にミカンが落ちた時にそのミカンを食べている様子が確認されるという珍しいケースも見受けられた。
日本では重要な水産資源で、タコ類の中では最も産額が多い。瀬戸内海の兵庫県明石市沖でとれる「明石ダコ」[2]が珍重される。カニ等を餌とした釣りも行われるが、物陰に潜む習性を利用した「蛸壺」（たこつぼ）漁法が主流である。大阪湾沿岸の弥生時代の遺跡からも、蛸壺用と思われる土器が大量に発掘されており、古くから食用にされていたことが窺える。
塩で揉み洗いしてから茹でて、酢蛸、煮物、寿司種、燻製や干物、たこ焼きや明石焼きの具などにする。茹でずに生で刺身にしたり、薄切りにしてしゃぶしゃぶにしたりすることもある。
日本の需要は国産だけでは賄いきれず、近縁種がアフリカ大陸北西の大西洋岸諸国等などからも輸入されている。モロッコからの輸入は一時日本での消費量の4割を占めていたが、乱獲のため漁獲量が減少し、2003年から年あたり8ヶ月程度の禁漁規制が続けられている。モーリタニアも有力な輸出元である。
一方、タコは英語で「デビル・フィッシュ」（Devil fish＝ 悪魔の魚）と呼ばれることもあり、欧米で食用にするのは長らく南欧の一部地域に限られていた。イタリアやギリシャなど地中海沿岸や、スペイン北西部のガリシア州（ポルボ・ア・フェイラというタコ料理が有名）などである。近年はこうした南欧のタコ食文化が、観光客や移民を通じてヨーロッパの他地域やアメリカ合衆国にも広がりつつあり、国際市場での日本の商社などとの購買競争が激しくなっている[3]。
日本水産は2017年6月8日、マダコの完全養殖技術を構築したと発表した[4][5]。
참문어(Octopus vulgaris)[1]는 문어과에 속한 연체동물의 일종이다. 돌문어, 피문어 등으로도 불린다.[1] 영어에서 그냥 문어(common octopus)라고 하면 이 종을 일컫는다. 이들은 지중해와 영국 남해안에서부터 최소한 아프리카 세네갈에 걸쳐 서식한다. 아소르스 제도, 카나리아 제도, 카보베르데 섬들에서도 발견된다.[2]
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