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The Pacific sleeper shark (Somniosus pacificus) is a secretive, deep-dwelling shark referred to by many fishermen as the “mud shark.” The Greenland shark is found in the North Atlantic Ocean and is a similar species.
Pacific sleeper sharks have been caught that exceed 20 feet (6 m) in length, which would weigh in at about 8000 pounds (3600 kg). This is approaching the size of adult orcas.
Pacific sleeper sharks are designed for stealth. Their eyesight is probably poor, but good eyesight is not necessary since they have an exceptional “sixth sense" to detect very slight electromagnetic fields. Muscle activity, even the beating of an animal’s heart or the movement of its diaphragm, emits an electrical signal that the sharks use to detect, locate and attack their victims. Under cover of darkness prey would be less likely to detect a sleeper shark coming up from the depths. Prey emits electromagnetic signals that guide the shark right in. For sleeper sharks, darkness is not a deterrent to detecting prey, but instead a cover or camouflage.
Pacific sleeper shark teeth are quite different in the lower jaw compared to the upper jaw. The upper jaw has small, sharp, conical teeth much like those in halibut. These are used to seize and hold prey. The teeth in the lower jaw are interlocking, forming a serrated blade used for slicing. Sleeper shark bite marks resemble large three-quarter moons or slices.
Sleeper sharks attack suddenly and without warning. A harbor seal might be floating on the surface of the ocean trying to catch its breath when it is attacked from below by a 400-pound (181-kg) sleeper shark. A bite to its midsection and the seal is eviscerated and struggling for its life. At minimum, the shark gets a large chunk of skin and blubber, likely enough to cause the seal soon to die. However the shark will finish the job by ripping the seal to bits, eating and digesting the entire animal. Smaller animals such as adult chum salmon or black cod usually are eaten whole.
Halibut and black cod struggling on a fisherman’s long line (bottom-set line with hundreds of baited hooks) attract sleeper sharks. The struggling fish emit signals that the sharks can detect from long distances. The sleeper sharks bite chunks out of the halibut. When sharks try to eat the cod whole, the same hook that caught the cod may hook the sharks. The struggling sleeper sharks tangle and damage commercial fishing gear, forcing many fishermen to change fishing areas.
CURRENT STATUS: Pacific sleeper shark numbers increased dramatically in the North Pacific during the 1980s and 1990s. In areas where few sharks ever were caught before, now fishermen are catching many more sleeper sharks. Many fishermen are reporting more and larger sharks each year in the Gulf of Alaska.
ECOLOGY/CONSERVATION: During the 1970s, temperatures in the North Pacific Ocean increased, followed by a change in species composition in the region. The ecosystem supported great quantities of shrimp and crab before the 1970s, but these species nearly disappeared and were replaced by pollock, cod, halibut and arrowtooth flounder. This species composition change is referred to as a “regime shift.” Other noteworthy and dramatic changes included decreases in sea lions, seals and forage fish (capelin, sandlance and herring) and increases in salmon sharks and Pacific sleeper sharks.
One theory explaining the regime shift involves increased winds, global warming, the Gobi Desert, iron and a group of phytoplankton (small single-celled plants) called “diatoms.” As the Earth warms due to global warming, scientists predicted, and have seen, stronger and more persistent winds. When these winds are especially strong they can sweep across the Gobi Desert of Mongolia carrying tons of dust laden with the element iron. Much of this iron is deposited in the North Pacific Ocean, which promotes the growth of a class of organisms called diatoms. Diatoms are single celled plants and can grow rapidly if the conditions are right. The diatoms use iron in a process that keeps them near the water’s surface and in the euphotic zone where they capture the sun’s energy. When the iron supply is used up, the diatoms sink to the bottom of the ocean. If there is lots of iron and it comes in a steady supply, the diatom population blooms and diatoms stay near the surface of the ocean and promote the surface food web and ecosystem. But if the winds are sporadic the diatoms grow, but soon deplete the iron in the water and sink to the bottom. This may be better for the ocean floor food web and ecosystem. The regime shift of the late 1970s may have been a result of the processes described here. As global warming changes wind patterns and the strength of the wind, we can expect more regime shifts and ones of greater magnitude.
Another theory of reduced marine mammal populations is that great white sharks have become abundant in Alaskan waters. Sharks are secretive by nature and do not readily reveal their presence, making it difficult for scientists to study. Sleeper shark populations are at record highs in the North Pacific, and they are preying on many species of fish and on some marine mammals. Sharks may be exerting an influence on the North Pacific marine ecosystem that will be long-lasting. Some scientists and many fishermen are concerned about what will happen, now that sharks are so common in the North Pacific Ocean. Many people have proposed shark predator-control programs without understanding the consequences.
Mathematical ecosystem models predict that there may be worse consequences if people reduce the shark population than there will be if they do not. Though sharks compete for some of the fish people catch and eat, sharks also reduce large changes in prey population numbers. According to some population models, removing sharks likely will result in increased salmon, black cod and pollock numbers. The increase in these smaller predatory fish would increase predation on smaller but extremely important forage fish such as herring, capelin and sandlance. The predicted outcome of the subsequent declines of the forage fish is for further reductions of seal and sea lion populations. This would be bad for fishermen. It also would be a big concern for those people trying to bring the sea lion back from the brink of extinction.
Pacific sleeper shark tissue is reported to be toxic to people and other animals. They are probably only preyed upon by other sharks. Commercial fishermen regularly kill Pacific sleeper sharks that they catch while fishing for black cod and halibut.
Satellite tags have been attached to Pacific sleeper sharks to determine their movements. Tag data indicates that individual sharks moved from the bottom, 2000 feet (610 m) deep, to the surface each night, apparently to feed. The limited tag data indicate that they did not migrate to other areas.
Pacific sleeper sharks are found in polar and sub-polar waters throughout the year. They occur in the Pacific Ocean from Baja California north to the Bering Sea, Chukchi Sea, Beaufort Sea, and to the Okhotsk Sea off of Japan. They inhabit cold, deep waters to depths exceeding 6500 feet (1981 m). At higher latitudes sleeper sharks use shallow as well as deep waters.
Deep underwater video has captured many Pacific sleeper sharks feeding together on whale carcasses. The sharks appear to be non-aggressive towards each other as they feed. No information is available on other sleeper shark social interactions.
Pacific sleeper sharks probably live more than 40 years. This age estimate is based upon the size this species obtains and upon the average growth rates. Determining the age of sharks is problematic. Bony fish can be aged by counting the annual rings on a bone in the ear called an otolith; most sharks do not have any bones and no shark has an otolith.
The species associated with this article are major components of the successionary communities arising around bathyal whale carcasses (though by no means the only whale-fall associated species).
A whale carcass arriving on the bathyal sea-floor (roughly 700-1000m depth) represents a massive influx of nutrients to an otherwise nutrient-poor ecosystem (Lundsten et al 2010a; Lundsten et al 2010b; Smith and Baco 2003). The background rate of carbon deposition to the deep-sea floor is on the order of tens of kilograms per hectare per year (Smith and Baco 2003); an adult whale can weigh up to 160 tons. Consequently, it has long been thought that whale carcasses must represent a significant source of nutrients for sea-bed communities. Additionally, since the discovery of deep-sea hydrothermal vents and cold seeps, it has been hypothesized that whale-falls may serve as stepping stones for the dispersal of organisms between chemosynthesis-dominated bottom communities (Smith and Baco 2003).
The community observed to spring up around whale carcasses has been characterized as having three major successionary stages (Danise et al 2012):
-Mobile scavenger stage: large, mobile detritivores consume the flesh of the whale.
-Enrichment opportunist stage: slow-moving or sessile organisms colonize the nutrient-enriched area in and around the carcass.
-Sulphophilic stage: a chemosynthesis-dominated system based on the sulfides released by anaerobic decomposition of bone lipids.
The duration of the first stage depends largely on the mass of the whale, ranging from a few months to up to one and a half years. Initially the community is dominated by large detritivores such as sleeper sharks and hagfish, but as the amount of flesh available decreases, smaller scavengers such as rattails, amphipods, and and lithodid crabs begin to replace them. Once the bulk of the tissue is removed from the skeleton, the community begins to shift to phase two. At this point, extremely dense populations of dorvilleid worms and other polychaetes, as well as crustaceans and gastropods colonize the area around the carcass, exploiting the rich organic material in the surrounding sediments. The rapid recruitment of these organisms suggests they may be opportunistic whale-fall specialists. Over time, without a discrete boundary, sulphide emission from anaerobic decay of bone lipids in the whale skeleton begins to support a chemosynthetic fauna similar to that found around cold seeps and hydrothermal vents, including bacteria, organisms with endosymbiotic bacteria, bacterial grazers, and small predators. This community may linger for up to several decades (Smith and Baco 2003). Fossil evidence suggests that a similar pattern of succession has been evolving since the late Miocene, and may even have operated on the carcasses of Cretaceous plesiosaurs (Danise et al 2012).
As always in ecology, this picture is somewhat oversimplified. In two 2010 articles, Lundsten et al observe that in addition to chemosynthetic fauna and whale-fall specialists, whale carcasses are often characterized by increased density of the background sea-floor organisms, particularly as time passes since the fall of the whale. Lundsten et al and Glover (2010) additionally found that there is a notable depth gradient in community structure, with fully sulphophilic ecosystems only developing on large, deep carcasses.
The function of whale-falls as stepping stones between cold seeps and hydrothermal vents remains unproven, but there is evidence for relatively large numbers of whale-fall specialist species, especially in the enrichment opportunist and sulphophilic stages (Smith and Baco 2003). Nearest-neighbor analyses of whale falls based on whale populations and the probability of a carcass sinking suggest that carcasses are distributed such that most organisms found in the latter two stages could easily disperse larvae between whale-fall sites. Unfortunately, this ecosystem may be endangered by declining whale populations and may even have already lost a great deal of diversity, as 19th century whale-fall density was likely up to six times higher than that in the present day (Smith and Baco 2003).
Der Pazifische Schlafhai (Somniosus pacificus) ist ein Hai aus der Ordnung der Dornhaiartigen (Squaliformes). Er gehört zur Familie der Schlafhaie (Somniosidae, von lateinisch: „Somnium“ = Traum) und kommt in der Tschuktschensee, im Ochotskischen Meer, im westlichen Nordpazifik von der Beringstraße entlang der Halbinsel Kamtschatka über die Kurilen bis zur japanischen Suruga-Bucht oder bis nach Taiwan und im östlichen Nordpazifik von den Aleuten entlang der Küste Alaskas bis nach Kalifornien oder Baja California vor. Die südliche Grenze des Verbreitungsgebietes ist nicht genau bekannt, da die Identität der dort vorkommenden Somniosus-Arten ungewiss ist.[1][2]
Der Pazifische Schlafhai hat einen relativ stämmigen, schwarzen oder schwärzlich-braunen Körper. Die gesicherte Länge beträgt bis zu 4,4 m, obwohl er möglicherweise ein Länge von mehr als 7 m erreichen kann. Damit würde er zu den größten Haiarten gehören. Die zwei Rückenflossen sind klein und etwa gleich groß. Die erste Rückenflosse liegt hinter der Körpermitte. Eine Afterflosse fehlt. Die den gesamten Körper dicht bedeckenden Placoidschuppen sind klingenartig mit einer nach hinten weisenden Spitze. Im Oberkiefer haben die Haie 46 bis 50 Zähne, im Unterkiefer sind es 26 bis 30.[1] Der Spiraldarm des Pazifische Schlafhais hat 32 bis 37 Windungen.[2]
Der Pazifische Schlafhai lebt in arktischen und gemäßigten Gewässern in der Nähe des Meeresbodens auf Kontinentalschelfen und Kontinentalhängen von der Oberfläche bis zu einer Tiefe von 2200 Metern. Die Haie ernähren sich von Fischen, Kopffüßern, Krebstieren, großen Weichtieren, Robben und Aas. Sie sind wahrscheinlich ovovivipar. Pro Wurf werden etwa 300 Junghaie geboren, die dann etwa 40 cm lang sind.[1][2]
Der Pazifische Schlafhai (Somniosus pacificus) ist ein Hai aus der Ordnung der Dornhaiartigen (Squaliformes). Er gehört zur Familie der Schlafhaie (Somniosidae, von lateinisch: „Somnium“ = Traum) und kommt in der Tschuktschensee, im Ochotskischen Meer, im westlichen Nordpazifik von der Beringstraße entlang der Halbinsel Kamtschatka über die Kurilen bis zur japanischen Suruga-Bucht oder bis nach Taiwan und im östlichen Nordpazifik von den Aleuten entlang der Küste Alaskas bis nach Kalifornien oder Baja California vor. Die südliche Grenze des Verbreitungsgebietes ist nicht genau bekannt, da die Identität der dort vorkommenden Somniosus-Arten ungewiss ist.
The Pacific sleeper shark (Somniosus pacificus) is a sleeper shark of the family Somniosidae, found in the North Pacific on continental shelves and slopes in Arctic and temperate waters between latitudes 70°N and 22°N, from the surface to 2,000 metres (6,600 ft) deep.[1][2] Records from southern oceans are likely misidentifications of relatives.[1] Its length is up to 4.4 m (14 ft), although it could possibly reach lengths in excess of 7 m (23 ft).[2]
Pacific sleeper sharks, which are thought to be both predators and scavengers, can glide through the water with little body movement and little hydrodynamic noise, making them successful stealth predators. They feed by means of suction and cutting of their prey. They have large mouths that can essentially inhale prey and their teeth cut up any pieces that are too large to swallow. They show a characteristic rolling motion of the head when feeding. Only in Alaska has the shark's diet been studied - most sharks' stomachs contain remains of giant Pacific octopus. They are also known to feed on bottom-dwelling teleost fishes, as well as soles, flounders, Alaska pollock, rockfishes, shrimps, hermit crabs, and even marine snails. Larger Pacific sleeper sharks are also found to feed on fast-swimming prey such as squids, Pacific salmon, and harbor porpoises. The diet of the Pacific sleeper shark seems to broaden as they increase in size. For example, a 3.7-m female shark found off Trinidad, California was found to have fed mostly on giant squid. Sleeper sharks found in Alaskan waters from 2 to 3 m (6.6 to 9.8 ft) seem to feed mostly on flounder, pollock, and cephalopods, while sleeper sharks 3.3 to 4.25 m (10.8 to 13.9 ft) long seem to consume teleosts and cephalopods, as well as marine mammals. A recent study in the Gulf of Alaska suggests that sleeper sharks may prey on juvenile Steller sea lions.[3]
Very little is known about the early life of Pacific sleeper sharks. They are believed to produce eggs that hatch inside the female's body (reproduction is ovoviviparous), but gestation time is unknown and litter sizes are thought to be about 10 pups. Its length at birth is about 42 cm (1.38 ft) or less.[4]
The average mature size is 3.65 m (12.0 ft) and 318–363 kg (701–800 lb). The largest Pacific sleeper shark verified in size measured 4.4 m (14 ft) long and weighed 888 kg (1,958 lb), although it could possibly reach 7 m (23 ft) or more.[2][5] In 1989, an enormous Pacific sleeper shark was attracted to a bait in deep water outside Tokyo Bay, Japan, and filmed. The shark was estimated by Eugenie Clark to be about 7 m (23 ft) long.[4] A single unconfirmed account exists of an enormous Pacific sleeper shark that potentially measured more than 9.2 m (30 ft) long [6]. If true, this would make the species the largest extant macro-predatory shark, and the third largest shark overall after the whale shark and the basking shark.
Due to living in frigid depths, the sleeper shark's liver oil does not contain squalene, which would solidify into a dense, nonbuoyant mass. Instead, the low-density compounds in the sharks' liver are diacylglyceryl ethers and triacylglycerol, which maintain their fluidity even at the lowest temperatures. Also, they store very little urea in their skin (like many deep sea sharks), but like other elasmobranchs, have high concentrations of urea and trimethylamine oxide (nitrogenous waste products) in their tissues as osmoprotectants and to increase their buoyancy.[7] Trimethylamine oxide also serves to counteract the protein-destabilizing tendencies of urea[8] and pressure.[9] Its presence in the tissues of both elasmobranch and teleost fish has been found to increase with depth.[9][10]
Because food is relatively scarce on the deep sea floor, the sleeper shark is able to store food in its capacious stomach. The sleeper shark's jaws are able to produce a powerful bite due to their short and transverse shape. The upper jaw teeth of the sleeper shark are spike-like, while the lower jaw teeth are oblique cusps and overlapping bases. This arrangement allows grasping and sawing of food too large to swallow. Pacific sleeper sharks have a short caudal fin, which allows them to store energy for fast and violent bursts of energy to catch prey.[4]
In 2015 a pacific sleeper shark was filmed near the Solomon Islands underneath an active volcano. The shark is able to survive in water with a high temperature and acidity.[11][12]
Sleeper sharks are preyed on by the offshore ecotype of killer whale off British Columbia.[13] In addition, like the Greenland shark, the parasitic copepod Ommatokoita elongata can often be observed consuming the shark's corneal tissue.
Pacific sleeper shark carcasses The Pacific sleeper shark (Somniosus pacificus) is a sleeper shark of the family Somniosidae, found in the North Pacific on continental shelves and slopes in Arctic and temperate waters between latitudes 70°N and 22°N, from the surface to 2,000 metres (6,600 ft) deep. Records from southern oceans are likely misidentifications of relatives. Its length is up to 4.4 m (14 ft), although it could possibly reach lengths in excess of 7 m (23 ft).
El tiburón dormilón del Pacífico (Somniosus pacificus) es una especie de tiburón perteneciente a la familia Somniosidae que habita alrededor del planeta sobre la plataforma continental y el borde del talud en aguas templadas en latitudes comprendidas de 70°N y 47°S, desde la superficie hasta los 2000 metros de profundidad. Su longitud alcanza los 4,4 m, sin embargo se piensa que puede alcanzar los 7 metros.
Esta especie vaga puede deslizarse por el agua realizando pocos movimientos y en forma silenciosa, lo cual le permite ser un depredador exitoso. Se alimenta mediante la succión y desgarramiento de sus presas. Tienen grandes bocas, pueden succionar presas y cortar cualquiera que sea demasiado grande para tragar. Solo se conoce la dieta de la especie en Alaska, donde la mayor parte de los estómagos contienen restos del pulpo gigante. También se sabe que consumen peces teleósteos del lecho marino, otros peces y crustáceos, e incluso caracoles de mar. Los especímenes más grandes pueden capturar nadadores veloces como calamares, salmones y marsopas. La dieta del tiburón dormilón del Pacífico parece ampliarse en cuanto aumentan de tamaño. Por ejemplo, en una hembra de 1,2 m hallada en Trinidad (California) se encontró principalmente calamar gigante. Una hembra de aproximadamente 4 metros capturada en la costa de Chile tenía en su estómago un delfín meridional sin aleta. Es una de los 3 animales (junto al cachalote, y el tiburón dormilón del Sur, una especie relacionada) que se alimenta de calamares gigantes y colosales adultos.[2] Debido a que un tiburón que puede llegar máximo a los 7 metros puede tener problemas para capturar y devorar un calamar de 12 a 14 m, se cree que se alimenta de cadáveres en lugar de atraparlos vivos. Sin embargo, esto sería posible si atrapara animales débiles o enfermos con limitada capacidad para defenderse.[3]
De acuerdo a un estudio publicado en 2011, las orcas marítimas del norte del Pacífico se alimentan rutinariamente de la especie, de la cual aparentemente consumen únicamente del hígado, desechando posiblemente la carne por resultarle tóxica.[4]
Se cree que la especie es capaz de producir huevos que pueden incubarse dentro de su cuerpo (reproducción ovovivípara), pero el tiempo de gestación se desconoce; el tamaño de huevos que llegan a eclosionar se cree que alcanza los 300. La longitud al nacimiento es de aproximadamente 42 cm o menos.[3]
El tamaño promedio es de 4 metros y de 300-360 kg aproximadamente. El ejemplar más grande capturado tenía 4,4 m, sin embargo FishBase acepta que posiblemente alcance 7 m. En 1989, un ejemplar enorme fue filmado en la bahía de Tokio, Japón y se estimó un tamaño de aproximadamente 7 m de largo.[3]
Debido a que frecuenta las frías profundidades el aceite del hígado no contiene escualeno debido a que podría solidificarse en una masa densa no flotante. En lugar de escualeno, tiene compuestos de baja densidad como éteres de diacilgliceril (DAGE) y triacilglicerol (TAG) los cuales se mantiene fluidos a bajas temperaturas. También almacenan algo de urea en la piel (como otros tiburones abisales) pero almacenan altas concentraciones de N-óxido de trimetilamina. Este ayuda a estabilizar las proteínas que componen los músculos natatorios, las hormonas digestivas y reproductivas que contrarrestan la intensa presión y el frío del fondo oceánico. Debido a que la comida es escasa en las profundidades esta especie es capaz de almacenar alimento en su espacioso estómago. sus mandíbulas son capaces de infligir poderosas mordidas por ser cortas y trasversas. Los dientes de la mandíbula superior tienen forma de clavo, mientras los inferiores tienen cúspides oblicuas y bases superpuestas. Esta disposición les permite sujetar y cortar alimentos demasiado grandes para tragar. Tiene una aleta caudal corta lo que le permite almacenar para los derroches violentos de energía requeridos para atrapar sus presas.[3]
|fechaacceso= requiere |url= (ayuda) El tiburón dormilón del Pacífico (Somniosus pacificus) es una especie de tiburón perteneciente a la familia Somniosidae que habita alrededor del planeta sobre la plataforma continental y el borde del talud en aguas templadas en latitudes comprendidas de 70°N y 47°S, desde la superficie hasta los 2000 metros de profundidad. Su longitud alcanza los 4,4 m, sin embargo se piensa que puede alcanzar los 7 metros.
Somniosus pacificus Somniosus generoko animalia da. Arrainen barruko Somniosidae familian sailkatzen da.
Somniosus pacificus Somniosus generoko animalia da. Arrainen barruko Somniosidae familian sailkatzen da.
Somniosus pacificus
Le Requin dormeur du Pacifique ou Laimargue dormeur (Somniosus pacificus) est une espèce de requin de très grande taille vivant dans l'Océan Pacifique.
Avec le cachalot, il est une des rares créatures à se nourrir de calmar colossal. Il peut mesurer près de 6 m avec une longueur moyenne de 4 m.
Hiu Pacific Sleeper, Somniosus pacificus, adalah hiu berat lainnya yang dapat hidup sepanjang 23 kaki dan berat hingga 362,87 kilogram (800 lbs). Satu hal yang membuat hiu jenis ini menarik adalah mereka merupakan salah satu dari sedikit jenis hiu yang dapat di temukan di daerah bertemperatur rendah (daerah menghadap kutub). Hal lainnya adalah mereka biasanya hidup di laut dalam, dengan kedalaman hingga 6500 kaki di bawah permukaan laut.
Hiu tidur Pasifik, yang juga pemakan bangkai dikenal, dapat melayang melalui air dengan gerakan tubuh sedikit dan sedikit suara hidrodinamik membuat mereka predator sukses. Mereka makan dengan penghisap dan memotong mangsanya.mereka memiliki mulut besar yang dapat menghirup mangsanya dan gigi mereka memotong setiap potongan yang terlalu besar untuk menelan.Mereka menunjukkan gerakan rolling karakteristik kepala saat makan. Hanya di Alaska memiliki diet hiu telah dipelajari - perut kebanyakan hiu 'mengandung sisa-sisa Gurita pasifik utara. Diet dari hiu tidur Pasifik tampaknya untuk memperluas karena mereka bertambah besar. Misalnya, hiu 3,7 m perempuan ditemukan dari Trinidad, California ditemukan telah makan sebagian besar pada Cumi-cumi raksasa. Hiu Sleeper ditemukan di perairan Alaska 2–3 m (6,6-9,8 ft) tampaknya memberi makan sebagian besar pada Ikan halibut dan cumi-cumi.
Ada sangat sedikit diketahui tentang kehidupan awal Pacific tidur hiu. Hiu tidur Pasifik diyakini menghasilkan telur yang menetas di dalam tubuh betina (reproduksi ovoviviparous), tapi kali kehamilan tidak diketahui dan ukuran sampah dianggap sekitar 10 ekor anak. Panjangnya pada saat lahir adalah sekitar 42 cm (1,38 kaki) atau kurang
Hiu tidur Pacific dilaporkan mencapai panjang hingga 25 kaki. Rata-rata ukuran dewasa 3.65 m (12,0 ft) dan 318–363 kg (701-800 lb). Terbesar tidur Pacific hiu diverifikasi dalam ukuran diukur 4,4 m (14 ft) panjang dan beratnya 888 kg (£ 1958), meskipun FishBase menerima bahwa itu mungkin bisa mencapai 7 m atau lebih.Pada tahun 1989, hiu tidur Pacific besar tertarik untuk umpan di air yang dalam di luar Tokyo Bay, Jepang dan difilmkan. Hiu diperkirakan oleh Eugenie Clark menjadi sekitar 7 m (23 kaki) panjang.
Castro, José I., The Sharks of North America. Oxford University Press (2011), ISBN 978-0-19-539294-4
Hiu Pacific Sleeper, Somniosus pacificus, adalah hiu berat lainnya yang dapat hidup sepanjang 23 kaki dan berat hingga 362,87 kilogram (800 lbs). Satu hal yang membuat hiu jenis ini menarik adalah mereka merupakan salah satu dari sedikit jenis hiu yang dapat di temukan di daerah bertemperatur rendah (daerah menghadap kutub). Hal lainnya adalah mereka biasanya hidup di laut dalam, dengan kedalaman hingga 6500 kaki di bawah permukaan laut.
Il lemargo del Pacifico (Somniosus pacificus) è uno squalo della famiglia dei Somniosidi. È diffuso nelle acque temperate di tutto il globo, dal 70° N al 47° S, dalla superficie ai 2000 metri di profondità. Il più grande lemargo di cui siano mai state ufficialmente determinate le dimensioni misura 4,4 metri, per un peso di 888 chilogrammi, ma si ritiene che questa specie possa raggiungere i 7 metri di lunghezza.
Il lemargo del Pacifico scivola lentamente attraverso le acque senza fare il minimo rumore. È un possente predatore che si nutre risucchiando le prede all'interno della grande bocca e facendole a pezzi con i denti affilati, in modo da poterle meglio inghiottire. Le sue abitudini alimentari sono state studiate dettagliatamente soltanto in Alaska: la maggior parte degli esemplari esaminati aveva all'interno dello stomaco resti di polpi giganti del Nordpacifico. Il lemargo si nutre anche di creature che vivono sul fondo, come sogliole, pianuzze, pollock, pesci pietra, gamberetti, paguri e perfino lumache di mare.
Gli esemplari più grandi catturano anche prede più veloci, come calamari, salmoni del Pacifico e focene comuni. La dieta del lemargo sembra variare a seconda delle dimensioni che raggiunge. Ad esempio, in una femmina di 3,7 metri catturata al largo di Trinidad (California) fu ritrovato gran parte del corpo di un calamaro gigante. Una femmina di 3,6 metri catturata al largo delle coste del Cile aveva nello stomaco l'intera carcassa di un lissodelfino australe. Gli esemplari dell'Alaska lunghi 1,95-3 metri sembra che si nutrano soprattutto di pianuzze, pollock e cefalopodi, mentre quelli lunghi 3,3-4,2 metri, oltre a mangiare teleostei e cefalopodi, catturano anche mammiferi marini.
Insieme al capodoglio, il lemargo del Pacifico è l'unica creatura a mangiare esemplari adulti di calamaro gigante e di calamaro colossale, come indicano i resti ritrovati negli stomaci[1]. Poiché è piuttosto difficile per uno squalo di 7 metri catturare e divorare calamari di 12-14 metri, si ritiene che si nutra solamente delle loro carcasse. Tuttavia, è anche probabile che il lemargo sia in grado di catturare calamari malati o denutriti, dato che in queste circostanze la combattività di queste creature diminuisce notevolmente[2].
Sappiamo molto poco sui primi anni di vita del lemargo del Pacifico. Si ipotizza che nasca da uova che si schiudono all'interno del corpo della femmina (riproduzione ovovivipara), ma il periodo di gestazione è ignoto, così come il numero dei nati per parto, sebbene sia stato ipotizzato che il loro numero di aggiri sui 300. La lunghezza alla nascita è di circa 42 cm[2].
Alcuni esemplari di lemargo del Pacifico possono raggiungere i 7,5 metri di lunghezza. Mediamente, però, la specie è lunga 4 metri e pesa 280–320 kg. L'esemplare più grande mai catturato era lungo 4,4 metri, ma secondo FishBase è molto probabile che alcuni esemplari possano raggiungere anche i 7 metri. Nel 1989 un lemargo enorme venne attratto da un'esca nelle acque al largo della baia di Tokyo (Giappone), dove fu filmato. Secondo Eugenie Clark questo squalo era lungo circa 7 metri[2].
Dato che il lemargo vive in acque profonde, dove le temperature sono molto basse, l'olio all'interno del suo fegato non contiene squalene, poiché esso potrebbe solidificarsi dando origine a una densa massa non galleggiante. Al posto dello squalene vi si trovano vari composti a bassa densità, come eteri diacilglicerili (DAGE) e triacilglicerolo (TAG), i quali mantengono la loro fluidità anche a temperature bassissime. Inoltre, il lemargo (così come molti altri squali di acque profonde) non immagazzina molta urea nella pelle, ma elevate concentrazioni di ossido di trimetilammina (un prodotto di scarto azotato). Questo aiuta il lemargo a stabilizzare le proteine che compongono i muscoli atti al nuoto e gli ormoni digestivi e riproduttivi contro le elevate pressioni e il freddo intenso delle profondità marine.
Dato che negli abissi è molto raro trovare cibo a sufficienza, il lemargo è in grado di immagazzinarlo in quantità nel suo grande stomaco. Le mascelle, piuttosto brevi e poste trasversalmente, consentono a questo squalo di dare morsi potenti. I denti situati sulla mascella superiore sono a forma di spillo, mentre quelli su quella inferiore hanno cuspidi oblique e basi sovrapposte. La loro disposizione permette di tranciare e fare a pezzi i bocconi troppo grandi da inghiottire. Infine, la pinna caudale, molto corta, permette al lemargo di conservare le energie per i rapidi e violenti scatti con cui cattura le prede[2].
Il lemargo del Pacifico (Somniosus pacificus) è uno squalo della famiglia dei Somniosidi. È diffuso nelle acque temperate di tutto il globo, dal 70° N al 47° S, dalla superficie ai 2000 metri di profondità. Il più grande lemargo di cui siano mai state ufficialmente determinate le dimensioni misura 4,4 metri, per un peso di 888 chilogrammi, ma si ritiene che questa specie possa raggiungere i 7 metri di lunghezza.
De Pacifische ijs- of sluimerhaai (Somniosus pacificus) is een vis uit de familie van sluimer- of ijshaaien (Somniosidae) en behoort tot de orde van doornhaaiachtigen (Squaliformes). De vis kan een lengte bereiken van 4,4 meter[2], mogelijk veel meer.
De Pacifische ijshaai leeft in de noordelijke Grote Oceaan in het poolgebied. De diepteverspreiding is 0 tot 2000 meter onder het wateroppervlak. Uit onderzoek van de maaginhoud van verschillende in netten gevangen dieren bleek dat dit dier zich evenals de potvis voedt met zeer grote inktvissen. De aanwezigheid van de reuzenkraak (Enteroctopus dofleini) in magen is aangetoond.[3] Predatie in de zuidelijke delen van de Indische Oceaan rond Kerguelen op Atlantische reuzeninktvis en kolossale inktvis is bewezen voor sluimerhaaien, waarbij niet duidelijk is of het de Groenlandse haai of de Pacifische sluimerhaai betreft.[4]
Op het zuidelijk halfrond aangetroffen grote sluimerhaaien worden als ondersoort van de Pacifische beschouwd, maar ook wel als aparte soort, de Antarctische sluimerhaai.
Bronnen, noten en/of referentiesDe Pacifische ijs- of sluimerhaai (Somniosus pacificus) is een vis uit de familie van sluimer- of ijshaaien (Somniosidae) en behoort tot de orde van doornhaaiachtigen (Squaliformes). De vis kan een lengte bereiken van 4,4 meter, mogelijk veel meer.
Somniosus pacificus, conhecido pelos nomes comuns de tubarão-dormedor-do-pacífico ou tubarão-dorminhoco-do-pacífico, é um peixe cartilagíneo do gênero Somniosus. Este cão-do-mar, enorme e lento, tem um corpo robusto e vive em águas frias a águas temperadas. Em geral atinge 4 metros de comprimento, mas há registo de indivíduos com mais de 6 metros.
De acordo com um estudo publicado em 2011, as orcas marítimas do norte do Pacífico rotineiramente alimentam da espécie, que, aparentemente, consomem unicamente o fígado, descartando possivelmente a carne por considerá-la tóxica.[1]
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Somniosus pacificus, conhecido pelos nomes comuns de tubarão-dormedor-do-pacífico ou tubarão-dorminhoco-do-pacífico, é um peixe cartilagíneo do gênero Somniosus. Este cão-do-mar, enorme e lento, tem um corpo robusto e vive em águas frias a águas temperadas. Em geral atinge 4 metros de comprimento, mas há registo de indivíduos com mais de 6 metros.
Загальна довжина сягає 7 м вагою до 900 кг. Голова середнього розміру, валькувате тіло. Грудні плавці невеликі без шипів. Зябра невеличкі. Рот великий. Зуби доволі великі у верхній щелепі. Забарвлення коричнювате або чорно-коричневе, на відміну від інших видів свого роду немає плям на тулубі чи плавцях.
Це придонна риба, зустрічається на великих глибинах. Активний хижак, наділений швидкістю. Живиться костистими рибами (тихоокеанським лососем, камбалою, мінтаєм тощо), головоногими молюсками, перш за все, велетенськими тихоокеанськими восьминогами, велетенськими кальмарами, також ракоподібними, інколи морськими свинями. Акула хапає здобич, втягуючи до пащі, а потім розрізає зубами.
Це яйцеживородна акула. Самиця народжує до 10 дитинчат 42 см завдовжки. Про терміни вагітності немає відомостей.
Мешкає у північній частині Тихого океану.
Somniosus pacificus là một loài cá mập thuộc họ Somniosidae, tìm thấy trên toàn cầu, trên thềm lục địa và dốc ở vùng biển ôn đới giữa vĩ độ 70 ° N và 22 ° N, từ độ sâu tới 2.000 mét (6.600 ft). Chiều dài của loài cá này lên đến 4,4 m và cân nặng 888 kg. FishBase công nhận có cá thể cá mập này dài đến 7m. Kích thước cá trưởng thành trung bình là 3,65 m (12,0 ft) và 318–363 kg (701-800 lb).
Loài này được biết đến là loài ăn xác thối, chúng có thể lướt qua nước với ít chuyển động cơ thể và ít tiếng ồn tạo ra dưới nước làm cho chúng là những kẻ săn mồi thành công. Chúng ăn bằng cách hút và cắt đứt con mồi. Chúng có miệng lớn và răng có thể cắn nhỏ những con mồi quá cỡ không thể nuốt được.
Somniosus pacificus là một loài cá mập thuộc họ Somniosidae, tìm thấy trên toàn cầu, trên thềm lục địa và dốc ở vùng biển ôn đới giữa vĩ độ 70 ° N và 22 ° N, từ độ sâu tới 2.000 mét (6.600 ft). Chiều dài của loài cá này lên đến 4,4 m và cân nặng 888 kg. FishBase công nhận có cá thể cá mập này dài đến 7m. Kích thước cá trưởng thành trung bình là 3,65 m (12,0 ft) và 318–363 kg (701-800 lb).
Somniosus pacificus Bigelow & Schroeder, 1944
Ареал
Тихоокеанская полярная акула[1][2], или североокеанская полярная акула[2] (лат. Somniosus pacificus) — вид рода полярных акул семейства сомниозовых акул отряда катранообразных. Обитает в умеренных водах Тихого океана. Встречается на глубине до 2000 м[3]. Максимальный зарегистрированный размер 440 см. Размножается яйцеживорождением[4]. Не представляет интереса для коммерческого рыболовства[5].
Впервые вид был научно описан в 1944 году[6]. Голотип представляет собой неполовозрелого самца длиной 1,91 м[5].
Тихоокеанские полярные акулы обитают в северной части Тихого океана у берегов Японии, Курильских островов, Тайваня, Китая, Нижней Калифорнии, в Охотском, Баренцевом, Беринговом и Чукотском морях и заливе Аляска. С 1980 года они перестали попадаться у Алеутских островов.
Эти акулы встречаются на континентальном шельфе и материковом склоне. В высоких широтах они заходят на линию прибоя и в литораль, а в низких широтах никогда не поднимаются на поверхность воды и предпочитают держаться на глубине до 2000 м[5]. Недавно проведённые исследования помеченных акул показали, что они регулярно совершают вертикальные миграции, преодолевая до 200 м за час. Днём они опускаются ниже эвфотической зоны, а ночью поднимаются на поверхность[7].
Максимальный зарегистрированный размер составляет 440 см. Однако были сделаны подводные фотографии акулы, чью длину оценивают приблизительно в 7 м[8]. Тело цилиндрическое, массивное. Рыло короткое и закруглённое. Голова довольно длинная. Расстояние от кончика рыла до оснований грудных плавников у особей размером от 406 до 430 см составляет 25—30 % от длины тела. Шипы у основания обоих спинных плавников отсутствуют. Спинные плавники одинаковой высоты, основание первого спинного плавника намного длиннее основания второго. Первый спинной плавник расположен ближе к брюшным нежели к грудным плавникам. Расстояние между основаниями второго спинного и хвостового плавника равно или превышает дистанцию между кончиком рыла и первой жаберной щелью. Короткие латеральные кили у основания хвостового плавника отсутствуют. Хвостовой стебель короткий. Хвостовой плавник асимметричный, нижняя лопасть хорошо развита. Расстояние между основаниями второго спинного и хвостового плавника равно 1,8 длины основания второго спинного плавника. Тело покрыто приподнятыми плакоидными чешуйками с крючком, в виде узких коронок, придающими коже грубый, колючий вид. Окраска тёмно-серого, почти чёрного цвета[5].
Тихоокеанские полярные акулы, вероятно, размножаются яйцеживорождением. До сих пор не беременные самки не попадались. Это может быть связано с их сегрегацией в местах, где отсутствует рыболовный промысел. Возможно, помёт очень многочисленный, внутри одной пойманной самки было обнаружено 300 крупных яиц[5][9]. Длина новорожденных составляет около 42 см[7]. Новорожденные попадаются в тралы в толще воды[10]. Самцы и самки достигают половой зрелости при длине 397 и 370—430 см, соответственно[11].
Тихоокеанские полярные акулы скользят в толще воды, затрачивая минимум усилий. Они засасывают и расчленяют добычу. Во время питания они совершают головой характерные вращательные движения. Наиболее полно изучен рацион тихоокеанских полярных акул, обитающих в заливе Аляска. 73 % содержимого желудков составляли остатки (чаще всего клювы) гигантских осьминогов. Кроме того, они охотятся на донных костистых рыб, таких как морской язык, камбала, сайда, морской окунь, а также креветок, крабов и даже морских улиток. Добычей крупных акул могут стать кальмары, тихоокеанские лососи и морские свиньи. С увеличением размера рацион тихоокеанских полярных акул становится более разнообразным[8]. Их привлекают глубоководные ловушки, расставленные на угольную рыбу. Иногда они попадаются в них сами или поедают добычу или наживку и уплывают[5]. Интересен тот факт, что будучи способными охотиться на подобную добычу, тихоокеанские полярные акулы в заливе Аляска не нападают на сивучей. Ко всему прочему они поедают падаль, например трупы серых китов[8].
Сами тихоокеанские полярные акулы могут стать добычей косаток.
При низкой температуре сквален, которым обычно богата печень акул, кристаллизуется, образуя плотную массу, и не может обеспечить плавучести и быть хранилищем энергии. Вместо него в печени тихоокеанских полярных акул содержатся диацилглицерин и триглицерид, которые остаются жидкими в условиях их обитания.
Приспособившись к скудным условиям глубоководья, эти акулы способны долгое время сохранять пищу в своём вместительном желудке. Например, содержимое желудка самки длиной 3,7 м, пойманной у берегов Тринидада, Калифорния, весило 136 кг. Устройство их челюстей и зубов позволяет им наносить мощные укусы, захватывать и пилящими движениями расчленять добычу, которая слишком велика, чтобы проглотить целиком. Короткий хвостовой стебель и крупный хвостовой плавник позволяют этим акулам совершить мощный рывок, чтобы схватить добычу[8].
В тканях тихоокеанских полярных акул присутствует мочевина и ТМАО, последний помогает стабилизировать при низкой температуре и высоком давлении белки[8].
Вид не представляет интереса для коммерческого промысла. Иногда в качестве прилова попадает в донные тралы. Пойманных акул выбрасывают за борт. Данных для оценки Международным союзом охраны природы статуса сохранности вида недостаточно[11].
Тихоокеанская полярная акула, или североокеанская полярная акула (лат. Somniosus pacificus) — вид рода полярных акул семейства сомниозовых акул отряда катранообразных. Обитает в умеренных водах Тихого океана. Встречается на глубине до 2000 м. Максимальный зарегистрированный размер 440 см. Размножается яйцеживорождением. Не представляет интереса для коммерческого рыболовства.
太平洋睡鯊（拉丁文學名：Somniosus pacificus）是軟骨魚綱角鯊目梦棘鲛科的睡鯊。
出沒於北緯70度到南緯47度之間的大陸棚和水溫較高的海域，其活動範圍可深至海底2,000米之處。其體長可達4.4米（14呎），但亦有一些文獻指出其身長最多可達7米。1990年，一隻巨型的太平洋睡鯊在日本東京海灣被食餌引誘而被捕獲，期間被攝錄了下來。那頭鯊魚估計長約7米（23呎），牠的體長可以跟大白鯊媲美，甚至可能比大白鯊更大。一些報紙，尤其是太陽報甚至不合理地說，那根本就是一隻「巨牙鯊」。
太平洋睡鯊吃魚類、章魚、烏賊、蟹、梭尾螺（triton）、海豹和腐肉。活物或新鮮者有很高含量的尿素，以及很多軟骨魚類的肌肉和體液內都含有的三甲胺氧化物（trimethylamine oxide）[1]。在經過其他動物的消化系統時，三甲胺（trimethylamine）會分離出來，對動物或人造成的效果就像喝醉了酒一般。動物如果不小心吃了太平洋睡鯊的鮮肉，由於神經毒素（neurotoxins）的影響，牠們會無法站立起來。牠和抹香鯨是僅有的兩種會吃大王烏賊的動物，這可從其腹中之物得知。由於一隻7米長的鯊魚要捕獵一隻12到14米長的大王烏賊並不太可能，因此人們推測太平洋睡鯊吃的是大王烏賊的腐肉，而不是自己活活捕捉一隻。[2]
牠們屬卵胎生之動物，一胎產300隻幼鯊。一隻剛出生的幼鯊僅長約42公分，或甚至比這還要更短。
於2009年一次虎鯨的獵殺後，研究人員發現殘骸至少來自16條太平洋睡鯊。
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分類 界 : 動物界 Animalia 門 : 脊索動物門 Chordata 亜門 : 脊椎動物亜門 Vertebrata 綱 : 軟骨魚綱 Chondrichthyes 亜綱 : 板鰓亜綱 Elasmobranchii 目 : ツノザメ目 Squaliformes 科 : オンデンザメ科 Somniosidae 属 : オンデンザメ属 Somniosus 種 : オンデンザメ S. pacificus 学名 Somniosus pacificus
オンデンザメ Somniosus pacificus （隠田鮫、英: Pacific Sleeper Shark）は、ツノザメ目オンデンザメ科に属するサメ。
ツノザメ目では近似種のニシオンデンザメと並ぶ最大種であり、体長は雄で440 cm、雌430 cm[2]が捕獲最大記録となっているが、これまでに深海で推定7 m以上の巨大な個体が撮影されたことから[3]、最大全長はさらに大きなものが存在する可能性も否定できない。成熟サイズは雌3.7 m[3]、雄全長397 cm以下[1]。
体型は流線形で、太く重量感がある。体色は黒色がかった灰色。2つの背鰭はほぼ同じ大きさで、やや後方に位置する。臀鰭はない。近縁の深海性ツノザメと違い、体に比べて目が小さく、鼻孔穴は大きい。口は大きく、上顎の歯は、下顎の歯よりも伸び、下顎の歯は中心を境に左右対称の鋸状になっている。胸鰭や背鰭も体の大きさに比べてやや小さい。皮膚は鮫肌特有のザラザラ感があるが、その身体は深海魚らしく、ぷよぷよとしており、柔らかい。
北太平洋の温帯から寒帯海域、日本、バハ・カリフォルニア（メキシコ）からベーリング海にかけて分布。生息水深帯は0（海表面）〜2,000 m付近まで[3]。
寒い海域では海洋表面にもみられるが、暖かい海域では表面には出現せず、もっぱら深海の海底付近で生活する。駿河湾ではしばしば本種が確認され、観察されている事でも有名。
肉食性で、表層から大陸棚付近の海底に生息する動物を捕食する。貪欲で口に入るものは何でも食べ、魚類やイカ、タコなど頭足類、甲殻類、海産哺乳類に加え、生物の死骸も食する[3]。サメであることと、身体の大きさから深海生態系の頂点に立つと思われ、人間以外には殆ど天敵もいない。
妊娠雌は確認されていないため繁殖様式は不明であるが、おそらく卵黄依存型の胎生である[3][1]。
極めて長寿であることが分かっており、成熟するのに約１５０年掛かると考えられている。近縁種のニシオンデンザメは5メートルになるのに400歳±100歳という分析があるため、当該種も同様であると予測されている。
体に寄生性カイアシ類がよく付いている。同じツノザメ目のダルマザメの攻撃も受けており、ダルマザメに体表を傷つけられた跡を見られる場合もある。
種々の漁業で混獲されるが、普通は捨てられる[1]。肉は食用には適さないが、肝臓は肝油の原料となる。しかし、深海性であるために漁獲高は低く、大型種とはいえ、日本では産業的にはそれほど重要種ではない。
人の泳げない深海性であるために直接関わることはなく、大きさの割に筋肉構造と泳ぐことが遅い事などから、人を襲うサメではない。体の大きさと食性から潜在的に危険な可能性もあるが、浅い海に引き揚げられた際には体の重みと身体組織関係から、漁獲されると激しく暴れる浅海の他の大型のサメと比較して、体の割には殆ど暴れることなく漁獲される。
深海に住むため、水族館での飼育記録はほとんどないが、2001年におたる水族館での飼育例が論文としてまとめられている[4]。 また、2013年の4月27日に富山県で捕獲された個体は魚津水族館の予備水槽で飼育された[5]。 さらに、2015年3月18日に静岡県の沼津港深海水族館にて、1.7メートルのオンデンザメが運び込まれ、7日間飼育展示された[6]。
オンデンザメ Somniosus pacificus （隠田鮫、英: Pacific Sleeper Shark）は、ツノザメ目オンデンザメ科に属するサメ。
태평양잠꾸러기상어(Pacific sleeper shark)는 잠꾸러기상어과에 속하는 상어의 한 종이다. 북태평양과 북극해의 대륙붕과 대륙사면 지대, 북위 70도에서 북위 22도 사이 지역의 수심 0 - 2000 미터 사이에 서식한다.[1][2] 그보다 남쪽에서 발견되었다는 보고들은 잠꾸러기상어속의 다른 종을 오동정한 것으로 추측된다.[1] 현재까지 발견된 최대 신장은 4.4 미터이나 7 미터도 넘게 자랄 수 있을 것이라 생각된다.[2]
