Giant Pacific Octopus

El pop gegant del Pacífic Nord (Enteroctopus dofleini) denominada comunament pop gegant de Califòrnia o polp del Pacífic Nord, és un gran cefalòpode del gènere Enteroctopus que té un cridaner color.

Descripció

Com altres membres de l'ordre dels octòpodes, usa pigments especials en la seva pell per canviar de color i camuflar-se en roques, plantes i fins i tot coralls.

Aquesta espècie de polp és l'invertebrat de major intel·ligència que es coneix. S'ha comprovat en diversos assajos de laboratori que pot aprendre observant, per exemple, destapant flascons imitant a altres polps i sortir de laberints creats per humans.

Hàbits

Atrapa el seu menjar a les nits, sobretot gambetes, cloïsses, llagostes i peixos. Però si ho necessita, atacarà a un tauró o a algun au que s'apropi massa a l'aigua, ajudat pels seus vuit tentacles.

Distribució

En l'oceà Pacífic] viu en les aigües temperades del sud de Califòrnia fins a les fredes aigües d'Alaska, i d'aquí pot ser trobat fins al Japó. No es troba en cap llista de preservació de les espècies perquè se sap molt poc de la seva població total, però sí que li afecten la contaminació de l'aigua i els canvis de temperatura.

Chobotnice velká (Enteroctopus dofleini) je druh měkkýše z čeledi chobotnicovití. Spolu s krakaticemi patří k největším měkkýšům a největším a nejinteligentnějším bezobratlovcům. Žije ve větších hloubkách. Ve starověku a středověku existovalo mnoho legend o tom, jak tato chobotnice napadla loď.

Popis

Chobotnice velká narůstá do délky 3-5 metrů a váží 10-50 kg. Rekordní jedinec měl však údajně rozpětí chapadel 9,8 metru a vážil až 272 kg.^[1] Plazí se po dně pomocí dlouhých chapadel, která jsou pokrytá přísavkami. Úkryt vyhledává v korálech, pod balvany a v puklinách. Dožívá se 4 roků.

Výskyt

Žije na severním okraji Tichého oceánu, od Japonska po Aleutské ostrovy a jižně po Kalifornii.

Chování

V ohrožení mění barvu nebo vypustí oblak „inkoustu“, který ji zahalí. Mladí jedinci si vyhrabávají díry pod kameny, v písku nebo ve štěrku, kde nacházejí útočiště před predátory (např. před tuleni, mořskými vydrami, žraloky nebo velkými rybami).

Potrava

Chobotnice velká loví potravu hlavně v noci. Živí se především kraby a humry, jakož i jinými korýši a měkkýši, menšími chobotnicemi a rybami. Potravu často konzumuje ve svém úkrytu, přičemž prázdné schránky a jiné nestrávené zbytky kořisti hromadí před vchodem.

Rozmnožování

Chobotnice žijí většinou samotářský život, s výjimkou období rozmnožování. Samec dopraví balík spermií, dlouhý až jeden metr, do plášťové dutiny samice pomocí speciálně modifikovaného chapadla. Samice klade tisíce vajíček do děr na dně a hlídá je až do vylíhnutí, což trvá 5 až 8 měsíců (v závislosti na teplotě vody). Ustavičně je zalévá proudem vody ze svého sifonu a čistí je chapadly od parazitů. Po celou dobu líhnutí nepřijímá potravu a krátce po narození potomstva uhyne.

Líhnutí mláďat

Při líhnutí jim matka pomáhá dostat se ven z díry, odkud plavou k hladině. První měsíce svého života stráví mezi planktonem na hladině. Pak se přesouvají ke dnu.

Synonyma

• Octopus apollyon (Berry, 1913)
• Octopus dofleini (Wülker, 1910)
• Octopus dofleini apollyon (Berry, 1912)
• Octopus dofleini dofleini (Wülker, 1910)
• Octopus dofleini martini (Pickford, 1964)
• Octopus gilbertianus (Berry, 1912)
• Octopus hongkongensis (Hoyle, 1885)
• Octopus madokai (Berry, 1921)
• Octopus punctatus (Gabb, 1862)
• Paroctopus apollyon (Berry, 1912)^[2]

Reference

V tomto článku byl použit překlad textu z článku Osmonoh gigantický na slovenské Wikipedii.

1. ↑ McClain C. R.; et al. (2015). Sizing ocean giants: patterns of intraspecific size variation in marine megafauna. PeerJ 3:e715 https://doi.org/10.7717/peerj.715
2. ↑ chobotnice velká [online]. biolib.cz [cit. 2015-06-03]. Dostupné online.

Externí odkazy

• Obrázky, zvuky či videa k tématu chobotnice velká ve Wikimedia Commons
• Taxon Enteroctopus dofleini ve Wikidruzích

Kæmpestillehavsblæksprutten^[1] (Enteroctopus dofleini) er en ottearmet blæksprutte, der er udbredt i det tempererede nordvestlige og nordøstlige Stillehav. Kæmpestillehavsblæksprutten kan blive 3-5 m lang, og er bundlevende ned til 750 m. Et tvivlsomt kadaver fundet i 1976 er blevet tolket til at have en spændvidde (målt fra armspids til armspids) på 9 m^[2].

Intelligens og levevis

Denne art er et af de største hvirvelløse dyr, men også et af de mest intelligente.^{[kilde mangler]} De kan endda løse simple problemer, såsom at finde vej i en labyrint ved tilfældigheder og huske vejen i lang tid derefter. Den har som andre blæksprutter store komplekse øjne og følsomme sugekopper, der kan skelne imellem objekter alene ved at berøre dem.

Som andre blæksprutter kan den hurtigt skifte farve ved at sammensnøre eller udvide pigmenterede områder i særlige celler kaldet kromatoforer, så den er altid camoufleret uanset baggrundens farve. Den bruger også farver til at vise sit humør og bliver rød når den er irriteret, og bleg, hvis den er stresset.

De fleste blæksprutter har ingen yngelpleje, men denne arts hunner vogter på æggene i op til otte måneder, indtil de klækkes. I denne periode æder hun ikke og leder vand over æggene, for at holde dem rene.

Kilder

Der Pazifische Riesenkrake (Enteroctopus dofleini) ist ein großer Kopffüßer aus der Gattung der Riesenkraken. Er lebt in der Nähe der Küsten des nordwestlichen Pazifiks meist auf nicht-felsigem Untergrund^[1] und wird als größter Krake angesehen.

Größe und Erscheinung

Der Pazifische Riesenkrake unterscheidet sich von anderen Arten allein schon durch seine Größe. Erwachsene Kraken erreichen häufig ein Gewicht von 23 bis 40 kg. Die größten Exemplare werden bis zu 270 kg schwer und können mit ausgespreizten Armen eine Kreisfläche von 9,50 m Durchmesser abtasten.^[2] Der Mantel oder „Kopf“ des Kraken hat eine Kegelform und enthält die wichtigsten Organe des wirbellosen Tieres. Die Haut des Kraken ist in entspanntem Zustand eher glatt. Durch die Steuerung kleiner Pigmentzellen in seiner Haut sowie mithilfe von Muskelkontraktionen ist jede Krakenart in der Lage, die Farbe, Musterung und Struktur der Hautoberfläche zu ändern, was den Tieren hilft, mit ihrer Umgebung optisch zu verschmelzen.

Ernährung

Dieser Krake frisst gewöhnlich Garnelen, Krabben, Muscheln und Fisch. Er hält die Beute mit seinen Saugnäpfen fest und öffnet die Schalen relativ schwacher Muscheln (etwa der Pazifischen Miesmuschel oder Venerupis philippinarum) mit seiner Armkraft; in härterschalige oder stärker bemuskelte wie Protothaca staminea nagt oder beißt er mit seinem Chitin-Schnabel ein Loch und injiziert vermutlich ein Toxin.^[3]

Intelligenz

Der Pazifische Riesenkrake gilt als sehr intelligent. In Aquarien löste er schwierige Aufgaben wie das Öffnen eines Glasdeckels, um an Nahrung als Belohnung zu gelangen. Außerdem kann er individuelle Menschen erkennen^[4] und das Verhalten anderer Kraken nachahmen.

Bedeutung

Meeressäugetieren wie dem Seehund, dem Seeotter oder dem Pottwal dient der Pazifische Riesenkrake als Nahrungsquelle. In den Vereinigten Staaten wird der Krake auch kommerziell gefischt.

Lebensdauer/Fortpflanzung

Mit einer mittleren Lebensdauer von drei bis fünf Jahren in der Natur gilt der Pazifische Riesekrake als kurzlebig für ein Tier seiner Größe. Oktopusmütter versorgen ihren Laich, der aus bis zu 100.000 Eiern besteht, indem sie ihn von Algen freihalten und vor Fressfeinden schützen. Nach etwa sechs Monaten schlüpfen die etwa reiskorngroßen Jungtiere, von denen nur wenige bis ins Erwachsenenalter überleben.^[5] Oktopusweibchen sind semelpar: Während der Brutpflege nehmen sie keine Nahrung auf und sterben nach deren Abschluss.^[6]

Schutz

Über diese einzeln lebenden Tiere ist wenig bekannt. Der Pazifische Riesenkrake wird gegenwärtig weder auf der Roten Liste gefährdeter Arten noch unter den schutzbedürftigen Tierarten des Washingtoner Artenschutz-Übereinkommens geführt. Allerdings ist er sehr empfindlich gegenüber Wasserverschmutzung und muss zukünftig möglicherweise geschützt werden, um sein Überleben zu sichern.

Quellen

• Datenblatt der Alaska Pacific University (engl.)

1. ↑ David Scheel: Characteristics of Habitats Used by Enteroctopus dofleini in Prince William Sound and Cook Inlet, Alaska. In: Marine Ecology, Bd. 23, Nr. 3, 24 September 2008, doi:10.1046/j.1439-0485.2002.02776.x.
2. ↑ Tardent, Pierre (1993). Meeresbiologie: Eine Einführung. Stuttgart & New York: Verlag Georg Thieme, S. 120.
3. ↑ Roland C. Anderson, Jennifer A. Mather: The packaging problem: Bivalve prey selection and prey entry techniques of the octopus Enteroctopus dofleini. In: Journal of Comparative Psychology, Bd. 121, Nr. 3, 2007, S. 300–305.
4. ↑ Roland C. Anderson, Jennifer A. Mather, Mathieu Q. Monette, Stephanie R. M. Zimsen: Octopuses (Enteroctopus dofleini) recognize individual humans. In: Journal of Applied Animal Welfare Science, Bd. 13, Nr. 3, 2010, S. 261–272, doi:10.1080/10888705.2010.483892.
5. ↑ Rendezvous mit einem Riesenkraken - Geheimnisvolle Wesen aus der Tiefe - Die ganze Doku. Abgerufen am 18. Januar 2021.
6. ↑ Giant Pacific Octopusby Shawn Laidlaw (engl.) Abgerufen am 28. März 2021

Weblinks

– Sammlung von Bildern, Videos und Audiodateien

The giant Pacific octopus (Enteroctopus dofleini), also known as the North Pacific giant octopus, is a large marine cephalopod belonging to the genus Enteroctopus. Its spatial distribution includes the coastal North Pacific, along Mexico (Baja California), The United States (California, Oregon, Washington, and Alaska), Canada (British Columbia), Russia, Eastern China, Japan, and the Korean Peninsula.^[3] It can be found from the intertidal zone down to 2,000 m (6,600 ft), and is best adapted to cold, oxygen-rich water. It is the largest octopus species, based on a scientific record of a 71-kilogram (157-pound) individual weighed live.^[4]

Etymology

The specific name dofleini was chosen by Gerhard Wülker in honor of German scientist Franz Theodor Doflein.^[5] It was moved to genus Enteroctopus by Eric Hochberg in 1998.^[6][7][8]

Description

Close-up of E. dofleini showing the longitudinal folds on the body and the paddle-like papillae

Close-up of suckers

Size

E. dofleini is distinguished from other species by its large size. Adults usually weigh around 15 kg (33 lb), with an arm span up to 4.3 m (14 ft).^[9] The larger individuals have been measured at 50 kg (110 lb) and have a radial span of 6 m (20 ft).^[3] American zoologist G. H. Parker found that the largest suckers on a giant Pacific octopus are about 6.4 cm (2.5 in) and can support 16 kg (35 lb) each.^[3] The alternative contender for the largest species of octopus is the seven-arm octopus (Haliphron atlanticus) based on a 61-kilogram (134-pound) incomplete carcass estimated to have a live mass of 75 kg (165 lb).^[10][11] However, a number of questionable size records would suggest E. dofleini is the largest of all octopus species by a considerable margin,^[12] including a report of one up to 272 kg (600 lb) in weight with a 9-metre (30-foot) arm span.^[13] Guinness World Records lists the biggest as 136 kg (300 lb) with an arm span of 9.8 m (32 ft).^[3][14] A UN catalog of octopuses sizes E. dofleini at 180 kg (400 lb) with an arm length of 3 m (9.8 ft).^[15]

Ecology

Diet

E. dofleini preys upon shrimp, crabs, scallop, abalone, cockles, snails, clams, lobsters, fish, squid, and other octopuses.^[16][17][18] Food is procured with its suckers and then bitten using its tough beak of chitin. It has also been observed to catch spiny dogfish (Squalus acanthias) up to 1.2 m (4 ft) in length while in captivity.^[19] Additionally, consumed carcasses of this same shark species have been found in giant Pacific octopus middens in the wild, providing strong evidence of these octopuses preying on small sharks in their natural habitat.^[20] In May 2012, amateur photographer Ginger Morneau was widely reported to have photographed a wild giant Pacific octopus attacking and drowning a seagull, demonstrating that this species is not above eating any available source of food within its size range, even birds.^[21]

Predators

Scavengers and other organisms often attempt to eat octopus eggs, even when the female is present to protect them. Giant Pacific octopus paralarvae are preyed upon by many other zooplankton and filter feeders. Marine mammals, such as harbor seals, sea otters, and sperm whales depend upon the giant Pacific octopus as a source of food. Pacific sleeper sharks are also confirmed predators of this species.^[22] In addition, the octopus (along with cuttlefish and squid) is a significant source of protein for human consumption. About 3.3 million tonnes (3.6 million short tons) are commercially fished, worth $6 billion annually.^[3] Over thousands of years, humans have caught them using lures, spears, pot traps, nets, and bare hands.^[23] The octopus is parasitized by the mesozoan Dicyemodeca anthinocephalum, which lives in its renal appendages.^[24]

Takoyaki stall in Nishi-Magome, Tokyo

Lifespan and reproduction

Enteroctopus dofleini spawning

The giant Pacific octopus is considered to be long-lived compared to other species, with lifespans typically 3–5 years in the wild. Many other octopuses go through a complete life cycle in one year, from egg to end of life.^[3] To help compensate for its relatively short lifespan, the octopus is extremely prolific. It can lay between 120,000 and 400,000 eggs which are coated in chorion, and attached to a hard surface by the female. The spawn is intensively cared for exclusively by the female, who continuously blows water over it and grooms it to remove algae and other growths. While she fulfills her duty of parental care the female stays close to her spawn, never leaving to feed, leading to her death soon after the young have hatched.^[25] The female's death is the result of starvation, as she subsists on her own body fats^[26] during this period of approximately 6 months.^[23] Hatchlings are about the size of a grain of rice,^[27] and very few survive to adulthood. Their growth rate is quite rapid: starting from 0.03 g (0.0011 oz) and growing to 20–40 kg (44–88 lb) at adulthood, which is an increase of around 0.9% per day.^[3] Because they are cool-blooded, they are able to use most of their consumed energy for body mass, respiration, physical activity, and reproduction.^[23] During reproduction, the male octopus deposits a spermatophore (or sperm packet) more than 1 m (3.3 ft) long using his hectocotylus (specialized arm) in the female's mantle. Large spermatophores are characteristic of octopuses in this genus.^[12] The female stores the spermatophore in her spermatheca until she is ready to fertilize her eggs. One female at the Seattle Aquarium was observed to retain a spermatophore for seven months before laying fertilized eggs.^[23]

Unlike males, only the female giant Pacific octopuses are semelparous, meaning they only breed a single time in their life.^[26] After reproduction, they enter a stage called senescence, which involves obvious changes in behavior and appearance, including a reduced appetite, retraction of skin around the eyes giving them a more pronounced appearance, increased activity in uncoordinated patterns, and white lesions all over the body. While the duration of this stage is variable, it typically lasts about one to two months. Death is typically attributed to starvation, as the females have stopped hunting in order to protect their eggs; males often spend more time in the open, making them more likely to be preyed upon.^[28]

Intelligence

Octopuses are ranked as the most intelligent invertebrates.^[29] Giant Pacific octopuses are commonly kept on display at aquariums due to their size and interesting physiology, and have demonstrated the ability to recognize humans with whom they frequently come in contact. These responses include jetting water, changing body texture, and other behaviors that are consistently demonstrated to specific individuals.^[30] They have the ability to solve simple puzzles, open childproof bottles and use tools.^[23] The octopus brain has folded lobes (a distinct characteristic of complexity) and visual and tactile memory centers. They have about 300 million neurons.^[23] They have been known to open tank valves, disassemble expensive equipment, and generally wreak havoc in labs and aquaria.^[23] Some researchers even claim that they are capable of motor play^[31] and having personalities.^[32]

Conservation and climate change

Giant Pacific octopuses are not currently under the protection of Convention on International Trade in Endangered Species of Wild Fauna and Flora or evaluated in the IUCN Red List.^[33] The giant Pacific octopus has not been assessed by the Monterey Bay Aquarium Seafood Watch, although other octopus species are listed.^[34] Combined with lack of assessment and mislabeling, tracking the species's abundance is nearly impossible. Scientists have relied on catch numbers to estimate stock abundance, but the animals are solitary and difficult to find.^[23] DNA techniques have assisted in genetic and phylogenetic analysis of the species' evolutionary past. Following its DNA analysis, the giant Pacific octopus may actually prove to be three subspecies (one in Japan, another in Alaska, and a third in Puget Sound).

In Puget Sound, the Washington Fish and Wildlife Commission adopted rules for protecting the harvest of giant Pacific octopuses at seven sites, after a legal harvest caused a public outcry.^[35] Populations in Puget Sound are not considered threatened.

Regardless of these data gaps in abundance estimates, future climate change scenarios may affect these organisms in different ways. Climate change is complex, with predicted biotic and abiotic changes to multiple processes including oxygen limitation, reproduction, ocean acidification, toxins, effects on other trophic levels, and RNA editing.

Giant Pacific octopus

Oxygen limitation

Octopuses have been found to migrate for a variety of reasons. Using tag and recapture methods, scientists found they move from den to den in response to decreased food availability, change in water quality, increase in predation, or increased population density (or decreased available habitat/den space)^[36] Because their blue blood is copper-based (hemocyanin) and not an efficient oxygen carrier, octopuses favor and move toward cooler, oxygen-rich water. This dependency limits octopus habitat, typically to temperate waters 8–12 °C (46–54 °F).^[3] If seawater temperatures continue to rise, these organisms may be forced to move to deeper, cooler water.

Each fall in Washington's Hood Canal, a habitat for many octopuses, phytoplankton and macroalgae die and create a dead zone. As these micro-organisms decompose, oxygen is used up in the process and has been measured to be as low as 2 parts per million (ppm). This is a state of hypoxia. Normal levels are measured at 7–9 ppm.^[37] Fish and octopuses move from the deep towards the shallow water for more oxygen. Females do not leave, and die with their eggs at nesting sites. Warming seawater temperatures promote phytoplankton growth, and annual dead zones have been found to be increasing in size.^[23] To avoid these dead zones, octopuses must move to shallower waters, which may be warmer in temperature and less oxygen-rich, trapping them between two low-oxygen zones.

Reproduction

Increased seawater temperatures also increase metabolic processes. The warmer the water, the faster octopus eggs develop and hatch.^[3] After hatching, the paralarvae swim to the surface to join other plankton, where they are often preyed upon by birds, fish, and other plankton feeders. Quicker hatching time may also affect critical timing for food availability.^[38] One study found that higher water temperatures accelerated all aspects of reproduction and even shortened lifespan by up to 20%.^[39] Other studies concur that warming climate scenarios should result in higher embryo and paralarvae mortalities.^[40]

Ocean acidification

The burning of fossil fuels, deforestation, industrialization, and other land-use changes cause increased carbon dioxide levels in the atmosphere. The ocean absorbs an estimated 30% of emitted anthropogenic CO₂.^[41] As the ocean absorbs CO₂, it becomes more acidic and lowers in pH. Ocean acidification lowers available carbonate ions, which is a building block for calcium carbonate (CaCO₃). Calcifying organisms use calcium carbonate to produce shells, skeletons, and tests.^[42] The prey base that octopuses prefer (crab, clams, scallops, mussels, etc.) are negatively impacted by ocean acidification, and may decrease in abundance. Shifts in available prey may force a change in octopus diets to other, nonshelled organisms.

Because octopuses have hemocyanin as copper-based blood, a small change in pH can reduce oxygen-carrying capacity. A pH change from 8.0 to 7.7 or 7.5 will have life-or-death effects on cephalopods.^[23]

Toxins

Researchers have found high concentrations of heavy metals and PCBs in tissues and digestive glands, which may have come from these octopus' preferred prey, the red rock crab (Cancer productus).^[43] These crabs bury themselves in contaminated sediments and eat prey that live nearby.^[3] What effects these toxins have on octopuses are unknown, but other exposed animals have been known to show liver damage, changes in immune systems, and death.

Effects on other trophic levels

Potential changes in octopus populations will affect upper and lower trophic levels.^[38] Lower trophic levels include all prey items, and may fluctuate inversely with octopus abundance. Higher trophic levels include all predators of octopuses, and may fluctuate with octopus abundance, although many may prey upon a variety of organisms. Protection of other threatened species may affect octopus populations (the sea otter, for example), as they may rely on octopuses for food. Some research suggests that fishing other species has aided octopus populations, by taking out predators and competitors.

Hectocotylus arm of an octopod

RNA editing

Some octopuses exhibit the ability to alter speeds of sodium and potassium ion movement across cell membranes, allowing them to live in very cold water. Researchers at the University of Puerto Rico's Institute of Neurobiology have found that they have altered protein synthesis, and can speed up production of potassium channels in cold water to keep up with sodium ion exchange. They are now looking into whether individuals can alter their protein synthesis in response to changing temperatures, or if this change occurs species-wide, over long-term adaptations. If changes are possible by the individual, these octopuses might be able to adapt quickly to changing climate scenarios.^[23]

See also

• Octopus wrestling
• Cephalopod size
• Squidward Tentacles, a fictional Giant Pacific octopus.

References

El pulpo gigante, pulpo gigante de California o pulpo del Pacífico Norte (Enteroctopus dofleini) es una especie de molusco cefalópodo de la familia Octopodidae;^[1]​ es el pulpo más grande que se conoce, con 9 m de longitud.^[2]​

Descripción

Como otros miembros del orden de los octópodos, usa pigmentos especiales en su piel para cambiar de color y camuflarse en rocas, plantas e incluso corales.

Crece más y vive más tiempo que cualquier otra especie de pulpo (4 años). El que ostenta el récord hasta ahora es un ejemplar de 9 metros y 272 kilogramos.^[2]​ Sin embargo lo habitual es que los adultos alcanzan un peso en torno a los 50 kg y una longitud de tentáculos de hasta 4,3 m.

Esta especie de pulpo es el invertebrado de mayor inteligencia que se conoce. Se ha comprobado en diversos ensayos de laboratorio que puede aprender observando, por ejemplo, destapando frascos imitando a otros pulpos y salir de laberintos creados por el hombre.

Distribución

En el océano Pacífico vive en las aguas templadas del sur de California hasta las frías aguas de Alaska, y de ahí puede ser encontrado hasta Japón. No se encuentra en ninguna lista de preservación de las especies porque se sabe muy poco de su población total, pero sí le afectan la contaminación del agua y los cambios de temperatura.

Comportamiento

Alimentación

Atrapa su comida por las noches, sobre todo camarones, almejas, cangrejos, langostas y peces, aunque también puede alimentarse de tiburones y aves marinas.^[3]​

Reproducción

En verano los ejemplares que han alcanzado la madurez sexual migran a aguas profundas para aparearse.^[3]​ El macho produce paquetes de esperma (espermatóforos) de hasta 1 m de longitud que traspasa a la hembra.^[3]​ En otoño e invierno vuelven a aguas de poca profundidad, donde la hembra incuba hasta 100.000 huevos puestos en hileras pegadas al techo de hendiduras.^[3]​

Referencias

Enteroctopus dofleini

La pieuvre géante du Pacifique (Enteroctopus dofleini) est une espèce de céphalopode de la famille des Octopodidae et vit surtout dans les eaux du Pacifique nord.

Description

Illustration historique.

La pieuvre géante, d'une couleur rougeâtre, comporte quatre paires de bras qui mesurent environ 3 m de longueur^[1] chacun.

Elle vit en moyenne de 3 à 5 ans. Les adultes pèsent de 25 à 43 kg (la plus lourde observée pesait 180 kg). Ses bras peuvent atteindre la taille exceptionnelle de 4,3 mètres^[2]. Quelques rares pieuvres de 9 mètres de long (corps + bras) ont déjà été observées dans le Pacifique-Nord. Sa taille bien qu'impressionnante a souvent été exagérée : le Kraken (pieuvre géante de la mythologie scandinave) correspond en fait sans doute aux calmars géants, bien plus gros. Rares sont les pieuvres qui atteignent l'âge adulte.

Ces pieuvres vieillissent de façon très semblable aux humains. Leur système immunitaire devient inopérant, puis le système reproducteur se dégrade, elles deviennent séniles, "ne peuvent plus penser" ni se nourrir^[1].

• 
• Dans son milieu naturel.

• Détail de la tête.

• 
• En captivité.

Alimentation

La pieuvre géante se nourrit essentiellement de crustacés et de mollusques tels que les crabes. Mais elle peut aussi manger des poissons, des requins et même d'autres pieuvres^[1].

Reproduction

Le mâle place sa semence dans l'orifice de respiration de la femelle puis il meurt^[1].

Après fécondation, la femelle accroche ses œufs, de la taille d'un grain de riz, en grappes, au plafond de sa cachette, elle pond à environ 18 mètres de profondeur. Elle les nettoie, les aère et les protège jusqu'à leur éclosion, pendant 150 jours, sans se nourrir, puis elle meurt. Si elle meurt avant, les œufs non surveillés n'ont aucune chance de survie^[1].

Les œufs sont ensuite emportés par le courant et finissent par descendre sur le fond, où les petits naissent et vivent^[1].

Comportement

Cette espèce est la star de nombreux aquariums.

C'est un animal curieux, craintif.

La pieuvre géante peut se fondre dans son milieu, se camoufler grâce aux pigments colorés de sa peau, mais elle ne voit qu'en noir et blanc.

Lorsqu'elle se sent en danger, la pieuvre géante libère un nuage d'encre noire qui la masque à l'agresseur, elle peut alors s'échapper ^[1]. Contrairement aux calmars, elle est dépourvue de griffes. Elle possède 8 bras tous munis de 200 ventouses environ. Grâce à celles-ci, la pieuvre géante peut soulever plus d'une tonne.

Sa relation avec l'homme est spontanément pacifique. Contrairement aux idées reçues, la pieuvre est inoffensive quelle que soit sa taille (à l'exception de la pieuvre à anneaux bleus). Elle est très intelligente et retient les situations pour mieux y réagir plus tard. Mais si elle a déjà été attaquée par l'homme, l'approcher de trop près peut être un réel danger. Il lui arrive parfois de jouer avec les plongeurs, si elle est mise en confiance. Toutefois il convient de prendre quelques précautions : il faut notamment éviter les gestes brusques, car par peur elle pourrait alors mordre de son bec qui ressemble à celui du perroquet, et qui peut aussi cracher du venin (douloureux mais pas dangereux, et utilisé essentiellement pour la chasse et presque jamais comme arme). Son bec est la seule partie dure apparente.

Une pieuvre géante peut facilement se glisser dans un trou ou une crevasse de quelques centimètres seulement, car elle est suffisamment molle pour étirer tout son corps et se glisser dans les plus petites failles, son seul obstacle étant son bec, mais elle sait anticiper par palpation si l'orifice dans lequel elle veut s'introduire sera assez grand pour laisser passer son bec ou non.

Malgré ses 3 cœurs, elle se fatigue très vite et ne peut pratiquer une activité physique que pendant quelques minutes.

Voir aussi

Références taxinomiques

• (en) Référence Catalogue of Life : Enteroctopus dofleini (Wülker, 1910) (consulté le 17 décembre 2020)
• (fr+en) Référence ITIS : Enteroctopus dofleini (Wülker, 1910)
• (en) Référence World Register of Marine Species : espèce Enteroctopus dofleini (Wülker, 1910)
• (en) Référence Animal Diversity Web : Enteroctopus dofleini
• (en) Référence NCBI : Enteroctopus dofleini (taxons inclus)

Notes et références

1. ↑ ^{a b c d e f et g} Au royaume des pieuvres géantes, Réalisateur : Sigurd Tesche, Documentaire, Arte, 15 novembre 2010 à 19:55.
2. ↑ (en)Smithsonian National Zoological Park Giant Pacific Octopus

gurita pasifik utara di perairan california

Gurita Pasifik Utara (Octopus dofleini) adalah salah satu mahluk laut terbesar di Samudra Pasifik utara dan barat laut, kepulauan Aleutian – Jepang hingga California Selatan – Alaska. Berat 10kg – 50kg (22-110lbs) dan panjang 3-5 meter (9.75-16ft). Umur rata-rata 3-5 tahun. Gurita pasifik terbesar tangan / tentakel dapat mencapai 10 meter (33-60ft) dan berat 272kg (600lbs). Merupakan hewan tak bertulang belakang (Invertebrata) dan pemakan daging (Karnivora) terbesar yang pernah ada.^{[butuh rujukan]}

Deskripsi

Berkepala bulat dan berwarna coklat kemerahan. Seperti gurita lainnya untuk menyamar dan melindungi diri, gurita pasifi8k memakai sel pigmen khusus di kulitnya untuk mengubah warna dan tekstur kulit menyerupai karang, tanaman laut, dan batu .

Reproduksi

seekor gurita pasifik utara betina sedang menjaga telur di sebuah celah di terumbu karang

gurita pasifik tidak memiliki musim kawin yang spesifik & bisa melakukan perkawinan kapan saja. gurita pasifik betina dapat menghasilkan telur berjumlah 100.000 butir telur, Gurita betina cukup lama untuk mengurus telurnya dan selama itu tidak makan berbulan-bulan kemudian mati. telur-telur gurita pasifik memerlukan waktu sekitar 3-12 bulan untuk menetas dimana semakin hangat suhunya, semakin cepat pula telur-telur itu menetas.

Makanan

gurita pasifik memerlukan makanan yang cukup untuk tumbuh hingga 1.8% berat badannya tiap hari. Dapat makan hingga 8 Kepiting tiap hari. Dapat tumbuh 3.58kg (7.89lbs) dalam 130 hari. Makanan favorit adalah kepiting, remis, ikan, cumi-cumi, lobster, dan kepala mackerel. dan terkadang gurita pasifik menyerang dan hiu, gurita pasifik memiliki mulut yang tajam dan mirip paruh untuk melubangi dan mengoyak daging juga dilengkapi racun untuk melumpuhkan mangsanya.^{[butuh rujukan]}

Galeri

• gurita pasifik utara jika dilihat dari dekat

• gurita pasifik utara di aquarium Washington D.C

• lengan gurita pasifik utara yang sedang di jemur

• 

Referensi

• http://animals.nationalgeographic.com/animals/invertebrates/giant-pacific-octopus/
• http://www.montereybayaquarium.org/animal-guide/octopus-and-kin/giant-pacific-octopus
• http://www.seattleaquarium.org/octopus

Il polpo del Pacifico^[2] (Enteroctopus dofleini (Wülker, 1910)), conosciuto maggiormente come polpo gigante del Pacifico, è un grosso cefalopode della famiglia degli Octopodidi.^[3] Vive lungo le coste del Nordpacifico, a profondità di circa 65 metri, ma lo si incontra anche in acque più basse o a profondità maggiori. È ritenuta la specie più grande di polpo: ne è stato, infatti, rinvenuto un esemplare vivo del peso di 71 kg^[4]. Un altro contendente per questo titolo è il polpo a sette tentacoli, di cui è stata ritrovata una carcassa del peso di 61 kg, ma che da vivo è stato stimato pesasse 75 kg^[5][6].

Descrizione

Primo piano di polpo gigante.

Il polpo gigante del Pacifico si distingue dalle altre specie per le maggiori dimensioni. Gli adulti pesano intorno ai 15 kg e sono lunghi mediamente 4,5 metri. Il mantello del polpo ha forma sferica e comprende quasi tutti gli organi più importanti. La pelle è rugosa ed è ricoperta da piccole sacche di pigmento, dette cromatofori, che consentono all'animale di cambiare colore a seconda dell'ambiente circostante (mimesi). Possiede inoltre un forte becco nel cavo orale che gli consente un'efficace predazione di crostacei molluschi e pesci.

Biologia

Riproduzione

Malgrado le grandi dimensioni, il polpo gigante vive solo 4 anni. Per ovviare alla brevità del suo ciclo vitale è molto prolifico. Le femmine depongono fino a 100.000 uova e muoiono alla loro schiusa. I piccoli sono grandi solo quanto un chicco di riso e solo in pochissimi arriveranno all'età adulta. Durante la riproduzione, il polpo maschio deposita una spermatofora (o sacca dello sperma) lunga più di 1 metro. Spermatofore così lunghe sono tipiche dei polpi del genere Enteroctopus^[7].

Alimentazione

Questa specie si nutre di piccoli crostacei e bivalvi. Le prede vengono afferrate con le ventose e poi frantumate con il robusto becco di chitina. Deposita i resti non commestibili delle sue prede all'entrata della sua tana (una grotta sul fondale) nella quale si nasconde dai suoi nemici.

Predatori

Il polpo gigante costituisce un'importante fonte di cibo per vari mammiferi e pesci marini come la foca comune, la lontra marina, il capodoglio ed alcuni squali. A volte, in cattività, è stato visto difendersi dallo spinarolo (cosa che si presume possa succedere anche in natura). Negli Stati Uniti viene inoltre pescato attivamente anche dall'uomo.

Conservazione

La lista rossa IUCN considera la specie come a rischio minimo.

Note

→ Interpretationes vernaculae

Enteroctopus dofleini est cephalopus magnus generis enteroctopodis, primum Wülker anno 1910 taxum. Habitat litore Oceani Pacifici septentrionalis, solitim circa 65 metris altitudine, sed etiam vivere potest in aquis superficialioribus sive altioribus.

Nexus interni

• Kraken

Nexus externi

Vicimedia Communia plura habent quae ad Enteroctopus dofleini spectant.

• Pelliculae de Enteroctopode dofleini apud YouTube

De reuzenkraak (Enteroctopus dofleini) is een inktvis uit de familie Octopodidae.

Kenmerken

Dit dier is vermoedelijk de grootste Octopoda gebaseerd op zijn grootste gemeten gewicht van 71 kg, hoewel de meeste volwassen exemplaren ongeveer 15 kg wegen en een armlengte hebben van 4,3 m. Het dier heeft een zakvormig lichaam met een roodbruine huid en een lichte onderkant. De lange armen zijn bezet met dubbele rijen zuignappen. Het dier kan 4 jaar worden.

Leefwijze

De reuzenkraak jaagt meestal op garnalen, krabben, sint-jakobsschelpen, zeeoren, kleinere koppotigen en vissen, die vaak wordt meegenomen naar zijn schuilplaats, waar deze rustig wordt opgepeuzeld. De prooi wordt stevig vastgegrepen en in stukken gebeten met de snavel. Daarnaast is uit observaties gebleken dat de soort zich ook voedt met de doornhaai, die soms wel tot anderhalve meter lang kan worden. Zelf worden ze gegeten door zeehonden, zeeotters, haaien en andere grote vissen. Ze prefereren schuilplaatsen met een nauwe toegang, zoals een grot of spleet in de rotsen, waar ze betrekkelijk veilig zijn voor hun belagers. Als hij bedreigd wordt, verschiet hij van kleur en scheidt een grote wolk inkt af, waardoor hij aan het zicht wordt onttrokken en wegvlucht

Voortplanting

Het vrouwtje plant zich 1 maal in haar leven voort. Ze legt zo een 100.000 eieren op een veilige plek die ze blijft bewaken tot ze uitkomen. Het duurt wel 6 maanden voor de eieren uitkomen. Ze streelt de eieren om te voorkomen dat algen er hun thuis van maken. Ze zorgt steeds voor vers water met hierin nieuwe zuurstof. Tot slot als de eieren uit komen blaast ze water langs de eieren om te helpen uit te komen. Dit is tevens haar laatste ademtocht. Ze bewaakt de eieren 6 maanden zonder zelf te eten. Ze verhongert. De jongen zwemmen naar het oppervlak, waar ze de eerste maanden in het plankton leven. Daarna gaan ze terug naar de bodem.

Verspreiding en leefgebied

Reuzenkraak geobserveerd in Pt Pinos op 65 meter diepte

Deze soort komt voor langs de noordelijke kusten van de Grote Oceaan, van Japan via de Aleoeten en Alaska tot Californië en is meestal te vinden op diepten rond de 65 meter.

Synoniemen

• Octopus punctatus Gabb, 1862
• Octopus dofleini Wülker, 1910
• Polypus dofleini Wülker, 1910
• Octopus dofleini dofleini (Wülker, 1910)
• Polypus apollyon Berry, 1912
• Octopus dofleini apollyon (Berry, 1912)
• Polypus gilbertianus Berry, 1912
• Octopus gilbertianus Berry, 1912
• Octopus apollyon (Berry, 1913)
• Octopus madokai Berry, 1921
• Paroctopus asper Akimushkin, 1963
• Octopus dofleini martini Pickford, 1964

• David Burnie (2001) - Animals, Dorling Kindersley Limited, London. ISBN 90-18-01564-4 (naar het Nederlands vertaald door Jaap Bouwman en Henk J. Nieuwenkamp).

Ośmiornica olbrzymia (Enteroctopus dofleini) – gatunek głowonoga z rodziny ośmiornicowatych (Octopodidae), jedna z największych ośmiornic, opisana przez Wülkera w 1910 r. Jest poławiana w celach konsumpcyjnych. Dawniej była powszechnie wykorzystywana jako przynęta.

Występowanie

Zasięg występowania tego gatunku obejmuje północną część Oceanu Spokojnego od Japonii po Aleuty i Baja California. Obserwowane są zazwyczaj na głębokościach do ok. 110 m p.p.m., ale mogą schodzić na głębokość ok. 1500 m^[2].

Budowa ciała

Ośmiornica olbrzymia ma czerwonawobrązowe ciało. Cztery pary ramion, połączone u nasady krótką błoną. Ciało waży zwykle do 60 kg, a długość worka trzewiowego to przeciętnie 50-60 cm^[3]. Rekord wynosi 272 kg^[2][4] i 9,6 m rozpiętości ramion^[2].

Tryb życia

Ośmiornica olbrzymia prowadzi drapieżny tryb życia. Zjada małże, kraby, ryby i kałamarnice. Posiada wiele środków obrony, takich jak: wytwarzana przez nią sepia, kamuflaż, jad, duża prędkość.

Osobniki tego gatunku żyją do 5 lat. Prowadzą samotniczy tryb życia na areale około 5 km²^[2].

Przypisy

Osmonoh gigantický (iné názvy: chobotnica veľká, chobotnica obrovská; lat. Enteroctopus dofleini) patrí medzi mäkkýše (Mollusca). Spolu s kalmármi patrí k najväčším mäkkýšom a najväčším a najinteligentnejším bezstavovcom. Žije vo väčších hĺbkach. V staroveku a stredoveku existovalo veľa legiend o tom, ako obrovská chobotnica napadla loď.

Opis

Osmonoh gigantický narastá do dĺžky 3 - 5 m a váži 10 - 50 kg. Plazí sa po dne pomocou dlhých, prísavkami pokrytých ramien. Úkryt vyhľadáva v koraloch, pod balvanmi a v puklinách. Dožíva sa 4 roky.

Výskyt

Žije na severnom okraji Tichého oceánu, od Japonska po Aleutské ostrovy a južne po Kaliforniu.

Správanie

V ohrození mení farbu alebo vypustí oblak „atramentu“, ktorý ju zahalí. Mladé jedince si vyhrabávajú diery pod kameňmi, v piesku alebo štrku, kde nachádzajú útočisko pred predátormi - tuleňmi, morskými vydrami, žralokmi a veľkými rybami.

Potrava

Osmonoh gigantický loví potravu hlavne v noci, živí sa predovšetkým krabmi a homármi, ako aj inými kôrovcami a mäkkýšmi, menšími chobotnicami a rybami, no obľubuje aj žraloky. Potravu často konzumuje vo svojom úkryte, pričom prázdne schránky a iné nestrávené zvyšky koristi hromadí pred vchodom.

Rozmnožovanie

Osmonohy žijú väčšinou samotársky život, s výnimkou obdobia rozmnožovania. Samec dopraví balík spermií, dlhý až jeden meter, do plášťovej dutiny samice pomocou špeciálne modifikovaného ramena. Samica kladie tisíce vajíčok do dier na dne a stráži ich až do vyliahnutia, čo trvá 5 až 8 mesiacov v závislosti od teploty vody. Ustavične ich polieva prúdom vody zo svojho sifónu a čistí ich ramenami od parazitov. Po celý ten čas neprijíma potravu a krátko po narodení potomstva hynie.

Liahnutie mláďat

Pri liahnutí im matka pomáha dostať sa von z diery, odkiaľ plávajú k hladine. Prvé mesiace svojho života strávia medzi planktónom na hladine, potom sa presúvajú ku dnu.

Iné projekty

• Commons ponúka multimediálne súbory na tému Osmonoh gigantický
• Wikidruhy ponúkajú informácie na tému Osmonoh gigantický

Zdroj

• BURNIE, David; KOVÁČ, Vladimír, a kol. Zviera: Obrazová encyklopédia živočíšnej ríše. Bratislava : Ikar, 2002. ISBN 80-551-0375-5.

Kuzey Pasifik dev ahtapotu (Enteroctopus dofleini), Kafadan bacaklılar sınıfının büyük bir üyesidir. Çoğunlukla Büyük Okyanus'un kuzey bölümlerinde görülür. Yaklaşık 65 metre derinliğinde görülen bu ahtapot türü, kanıtlanmaya çalışılmakla birlikte en büyük ahtapot türüdür. Ağırlık rekoru 272 kg'dır. Bir kolunun uzunluğu 9 m olabilir. Karides, yengeç, denizkulağı, midye ve balık dahil neredeyse tüm deniz ürünleriyle beslenebilir. Bu balıkların arasında köpekbalığı da bulunur. Bir beyaz tepeli resif köpekbalığını avlarken kaydedilmiş görüntüleri vardır.

Bạch tuộc khổng lồ Thái Bình Dương (Danh pháp khoa học: Enteroctopus dofleini) còn được biết đến với tên gọi là Bạch tuộc khổng lồ Bắc Thái Bình Dương là một loài bạch tuộc cở lớn trong chi Enteroctopus phân bố ở bờ biển phía Bắc Thái Bình Dương và có ở California, Oregon, Washington, British Columbia, Alaska, Nga, Bắc Nhật Bản và Hàn Quốc^[1]. Chúng có mặt ở khắp các vùng nước ôn đới của Thái Bình Dương, từ nam California tới Alaska, tây tới đảo Aleutian và Nhật Bản.

Đặc điểm

Chúng phát triển lớn hơn và sống lâu hơn nhiều loài bạch tuộc nào khác. Kích thước kỷ lục của chúng theo một mẫu vật được lưu giữ dài 9,1 mét và nặng 272 kg. trung bình chúng dài 5 mét và nặng 50 kg. Chúng sống khoảng 4 năm, cả con đực và con cái chết sau khi đẻ. Con cái sống đủ lâu để chăm sóc trứng của chúng, nhưng không ăn trong giai đoạn ấp trứng dài nhiều tháng và thường chết ngay sau đó. Loài này khá giống tắc kè hoa, có thể thay đổi hình dạng để giả thành đá và san hô có cấu trúc phức tạp.

Bạch tuộc khổng lồ có đầu lớn phồng ra và thường có màu nâu hơi đỏ. Giống như những thành viên khác của họ bạch tuộc, chúng dùng những tế bào sắc tố đặc biệt trong da để thay đổi màu sắc và hình dạng và có thể hòa trộn với những loài san hô có cấu trúc phức tạp nhất, cỏ biển và đá. Chúng đi ăn vào ban đêm, sống chủ yếu nhờ tôm, nghêu, tôm hùm, cá, nhưng cũng được biết là đã tấn công và ăn thịt cá mập và chim, dùng miệng có dạng mõm nhọn sắc để đâm và xé con mồi.

Tập tính

Là sinh vật thông minh cao, bạch tuộc khổng lồ Thái Bình Dương học được cách mở nắp hũ, bắt chước các loài bạch tuộc khác, và giải các mê cung trong thử nghiệm ở phòng thí nghiệm. Số lượng của chúng chưa được biết rõ, và hiện nay chưa có tên trong danh sách các loài có nguy cơ hoặc dễ bị nguy hiểm. Tuy nhiên chúng rất nhạy cảm với điều kiện môi trường và có lẽ đang chịu ảnh hưởng từ sự ô nhiễm môi trường mức độ cao ở khu vực phân bố của chúng.

Trong ẩm thực

Bạch tuộc khổng lồ ở Nhật Bản còn được gọi là Mizudako, cũng được gọi là Shiodako và Oodako là loài lớn tới 3 mét. Nó được bắt ở độ sâu 100 – 1000 mét vào mùa thu và mùa đông ở miền bắc Nhật Bản. Nó thường được bán dưới dạng đông lạnh. Sau đó nó được cắt dưới dạng rã đông nửa chừng dùng làm các món: Mizudako sashimi, xa lát Mizudako. Nó cũng thường được luộc và ngâm trong giấm. Trứng của nó cũng được dùng làm sushi.

Tham khảo

Liên kết ngoài

• CephBase: Enteroctopus dofleini
• The Cephalopod Page

• Octopus punctatus Gabb, 1862
• Octopus dofleini Wülker, 1910
• Polypus dofleini Wülker, 1910
• Octopus dofleini dofleini (Wülker, 1910)
• Polypus apollyon Berry, 1912
• Octopus dofleini apollyon (Berry, 1912)
• Polypus gilbertianus Berry, 1912
• Octopus gilbertianus Berry, 1912
• Octopus apollyon (Berry, 1913)
• Octopus madokai Berry, 1921
• Paroctopus asper Akimushkin, 1963
• Octopus dofleini martini Pickford, 1964

• 1 Морфология
• 2 Жизненный цикл
• 3 Среда обитания
  • 3.1 Враги
• 4 Распространение
• 5 Хозяйственное значение

• Найти и оформить в виде сносок ссылки на независимые авторитетные источники, подтверждающие написанное.
• Переработать оформление в соответствии с правилами написания статей.

北太平洋巨型章魚（學名：Enteroctopus dofleini），又名北太平洋巨人章魚，是一種巨型的章魚。它們分佈在北太平洋海岸水深達65米的地方，也可以走到較淺或較深水的地方居住。因曾發現重達71公斤的個體，故有指它們是最大的章魚。^[1]另外卻有指七胳膊章魚才是最大的章魚，因曾發現重達61公斤的屍體，估計活體可以重達75公斤。^[2][3]不過仍有很多紀錄指北太平洋巨型章魚可能是最巨大的。^[4]

體型及特徵

北太平洋巨型章魚的近鏡，可以見到身體上的皺褶及槳狀的乳突。

北太平洋巨型章魚的體型很大，成體重約15公斤，臂展開可達4.3米。^[5]虽然曾有272公斤及臂展達9米的最高纪录，但这个纪录极不可信。^[6]外套膜呈球狀，內藏了其主要器官。皮膚光滑，只要收縮或舒張色素細胞，就可以改變皮膚的顏色，輕易的隱身在環境之中。

食性

北太平洋巨型章魚的主要獵物有蝦、蟹、扇貝、鮑魚、蛤蜊及魚類。它們利用吸盤將食物送入口中，並用甲殼素的喙將獵物咬碎。圈養的北太平洋巨型章魚曾捕捉長達1米的白斑角鯊^[7]另外，野外北太平洋巨型章魚的排出物中也有白斑角鯊的屍體，故估計它們天生是會捕獵此種鯊魚的^[8]

掠食者

北太平洋巨型章魚的天敵有港海豹、水獺、太平洋睡鯊及抹香鯨。它們在美國也被漁獵。

壽命及繁殖

北太平洋巨型章魚因體型巨大，估計壽命很短，野外只會活到3-5歲。由於它們的壽命很短，其繁殖能力十分之強。它們可以產達10萬顆卵，雌章魚會傾出生命來保護卵。雛生的大小只如飯粒，只有非常少量能夠生存至成體。在繁殖期間，雄章魚會排出長達1米的精囊。^[4]

保育

對於北太平洋巨型章魚所知甚少，只知道它們是獨居的，並不受世界自然保護聯盟所保護。

參考

外部連結

• 頭足綱資料庫（CephBase）： 北太平洋巨型章魚
• Giant Pacific Octopus
• Giant Pacific Octopus: Fact Sheet

ミズダコ・ミズタコ（水蛸、学名：Enteroctopus dofleini）は軟体動物八腕類上目マダコ科に属するタコの一種で、世界最大のタコでもある。別名オオダコ（大蛸）とも言う。

分布[編集]

寒海性のタコで、主に日本の東北地方以北の海に広く分布し、北太平洋が主な生息場所になる。アラスカ、カナダをはじめ、北アメリカ大陸北西部沿岸海域にも生息している。

特徴[編集]

タコ類最大だけあって体、吸盤ともに非常に大きい。体長は足（腕）を広げると3-5m、体重も10-50kgにもなり、最大記録では体長9.1m、体重272kgに達する^[2]。口のカラストンビは人の握り拳大ほどもあり、これで餌であるカニの甲羅や貝の殻を咬み砕くと言われるが、他のタコのような唾液のチラミン毒素の強さについては不明。

体のほとんどが柔軟な筋肉であるため力が強く、巨大な個体に絡まれたら人間でも危険である。潜っていた時に襲われ、溺死した例もある。ただし、近づきすぎたり、刺激したりしない限りは故意にダイバーを攻撃することはない。陸上では水中と違い、重い体重を支えることはできず、動けなくなってしまう。

カナダ方面では大型化し、体長3.5mにも達する大物も少なくないと言われるが、生息地域が寒い海ということもあり、マダコなどに比べれば、まだまだ生態的に未解明な部分が多い。

生態[編集]

餌は主にケガニやタラバガニなどの大型甲殻類や、魚類やホタテガイのような貝に、ウニ等も手当たり次第にその巨体を良いことに捕獲し、貪欲に食べてしまう。本種が最大のタコでいられるのも、寒い海に生息するそれら大型甲殻類などの餌が豊富であり、そのために寒海には住めない他のタコ類との競争も減り、大型化していったと考えられる。

天敵はイルカやラッコ、アザラシやトドといった海生哺乳類に、サメ類などの大型魚類などで、襲われると周囲のものに擬態したり、墨を吐いたりして逃走するが、それらに捕食されるのは小さな個体である場合が多く、巨大な個体なら逆にサメを捕食してしまう事すらあるほどの力を持っていて、充分に育った成体にはあまり敵はいないだろうとも思われる。また水族館では、同じ水槽内にいたアブラツノザメを攻撃し死亡させた例もある^[3]。

他の多くのタコと同じく、寿命は2-3年とされている。雄は雌と交尾した後、雌は卵を守り、孵化を見届けた後に一生を終える。地域別には4年ほども生きる個体もいるといわれる。

雌雄の違いは雄の方が体も吸盤も大きく、相手を捕らえて抱え込んだり、吸い付いたり力も強力だとされているが、その吸盤の大きさから配列は大小ともに歪な見かけがする。雌は雄に比べて、吸盤の配列や大きさが、比較的均等になっている。

また、他のタコや周囲の状況に擬態したり、迷路を解いたりするなど高い知能を有している^[2]。

日本での利用[編集]

捕獲、展示されたミズダコの雄

稚内のたこしゃぶ

本種は人間によって食用目的に捕獲されている。体が大きい分、水産上重要種と見なされ、蛸壺にて漁獲されている。また、マダコの流通が少ない北海道や東北地方でタコと言うと大抵は本種であり、北海道では本種の漁獲高が最も多い。現在、需要が高いが、乱獲による個体数の減少も懸念されている。「北海ダコ」という別称もある。

利用部位[編集]

北海道・東北では、マダコの代わりに各種タコ料理として利用され、正月料理に使われるタコの多くは、ミズダコである。本来タコは、腕（足）の方が利用価値は高い。しかし、産地では、足より胴（頭）の方が食され利用頻度は高い（足よりも頭の方が安いという事情もある）。その他、口（顎板：通称タコトンビ）が食用とされる。ちなみに、タコ卵巣（たこまんま）を食するものは、ヤナギダコである。

マダコに比べて皮膚だけでなく肉質も柔らかく、水っぽく、それが和名の由来になっている^[4]。「コクが強いマダコよりおいしくない」と言う人もいれば、「食感としてはミズダコの方が歯触りが良い」と言う人や、吸盤が大きいミズダコの方を好む人もいる。体の大きさから含まれるタウリンの多さではマダコをしのいでいる。またミズダコのうち、雌の方が雄よりも味が良いという意見もある。

北海道での料理方法として、刺身（足・頭）、寿司、たこ焼き（足・頭）の他には、おでんや塩茹で、たこしゃぶ（しゃぶしゃぶ）、干物、燻製、酢蛸、塩辛（イカの塩辛とは別物）などがある。

その他[編集]

水族館でも飼育され、展示、公開されている。

出典・脚注[編集]

1. ^ “WoRMS”. ^ ^{a b} “ミズダコ”. ナショナルジオグラフィック. ^ ナショナルジオグラフィック日本語公式サイト　動画‐動物‐魚類‐衝撃映像　サメVSタコ Archived 2011年2月25日, at the Wayback Machine.
2. ^ 【食あれば楽あり】ミズダコ／歯応え変化、うま汁ジュル（小泉武夫）、『日本経済新聞』夕刊2018年5月14日くらしナビ面。

関連項目[編集]

• ダイオウイカ

언어학 용어에 대해서는 문어 (언어) 문서를 참고하십시오.

문어(文魚; 학명: Enteroctopus dofleini)는 문어과에 속하는 연체동물이다. 둥근 머리 모양의 몸체에 두 눈이 있고 빨판이 달린 8개의 다리가 입 주변에 달려 있다. 약 300종이 있으며, 문어목(Octopoda)은 오징어, 갑오징어, 앵무조개목(nautiloids)이 속한 두족강으로 분류된다. 대왕문어, 큰태평양문어라고도 한다.

이름

문어는 지역에 따라 대문어, 대팔초어, 물낙지 등으로 불린다. 문어는 중세 국어에서 ‘믠어’라고 불렀다. 한자 표기 文魚는 ‘믠어’를 한자로 빌려적은 취음이고, 한문으로는 팔초어(八梢魚)로 불렸다.

생태

제주 문어의 산란

문어는 다리길이 4.3 미터 몸무게 15Kg까지 자라며 수명은 대략 3~5년이다. 봄에서 여름에 걸쳐 수심 40~60 미터 해저에 10만개 이상의 알을 낳으며 산란을 마친 암컷은 6개월여 알을 지키다 죽는다. 살아나는 알은 불과 몇개 밖에 되지 않는다. 오징어와 마찬가지로 짝짓기를 한 후에 수명을 다한다.^[1] 중국 동해안, 한국, 일본, 캐나다와 미국의 서해안 등 북태평양 연안에서 서식한다.

문어는 먹물 주머니가 있어 위협을 느끼면 먹물을 뿜고 달아난다. 또한 문어의 피부는 주위 환경에 따라 색상을 바꿀 수 있어 이를 이용해 자신을 보호한다.

문어는 신경계가 주로 다리에 있어서 변신을 잘 할 수 있으며, 지능이 매우 높아 화산폭발을 미리 알고 피하는 것으로 알려져 있다. 거울을 보여주었을 때 자기 자신을 차츰 인식하는 것으로 알려져 있다. 한 실험에서는 통 속에 든 먹이(게)를 먹기 위해 뚜껑을 돌려 통을 열었다고 한다.

문어가 도구를 사용하는 장면이 수중카메라로 발견되었다. 문어는 코코넛 껍데기를 운반해 은신처를 만드는 무척추동물의 첫사례로 기록되었다.

효능

문어는 타우린이 풍부해, 혈액 내 콜레스테롤을 낮춰주고 피를 맑게 해 혈관에 탄력을 준다. 간의 해독작용을 도와주어 피로 해소에 좋으며, 심장병과 당뇨 등을 예방해준다. 타우린은 망막의 기능을 도와주어 눈 건강에 좋으며, 단백질이 풍부해 다이어트 식품으로 좋다.^[2]

이용

문어는 각종 요리에 사용된다. 갓잡은 것을 삶거나 말린 것을 구워 먹는다.

문어회

문어과에 속하는 종

문어과에 속하는 다른 종들에는 참문어, 주꾸미, 낙지 등이 있다. 한반도의 연안에는 약 50여 종의 문어과 생물이 서식하고 있다.

각주