The purpleback flying squid or purpleback squid (Sthenoteuthis oualaniensis) is a species of cephalopod in the family Ommastrephidae, occurring in the Indo-Pacific. It is considered one of the most abundant large squids.
S. oualaniensis are sexually dimorphic where the females tend to grow larger than the males in most cases.[3] Dimorphism differentiation occurs in the sucker ring dentition in which different sizes occur which suggests that a feeding spectrum occurs among male and female individuals.[3]
The species has a complex population structure, comprising three major and two minor forms with different morphology, anatomy, geographical distribution, and period of spawning.[3][4][5] These forms include a giant form, a medium form with a double lateral axis on the gladius, a medium form with a single lateral axis on the gladius, a dwarf form, and a smaller earlier maturing form.[3][6] The medium form is characterized by a dorsal photophore patch and fused mantle locking apparatus, it is the most common or “typical” form, and has the largest geographical distribution divide with a deeper vertical distribution when compared to the dwarf form.[3][4][7] The dorsal mantle length (ML) of sexually mature adult males and females is 120 – 150 mm and 190 – 250 mm respectively.[7] The smaller forms include a dwarf from an early maturing form, these two forms can be classified under the same category due to significant similarities as there is some disagreement in the literature.[3][4][7] The smaller forms have no dorsal photophore patches and tend to reside in the equatorial waters (10 – 15 º N and S) of the Indonesian-Pacific Oceans, in which it spends the majority of its life in the upper mixed layers.[3][4][7] The ML in the adult's males and females is 90 – 100 mm and 90 – 120 mm respectively.[7] The giant forms are categorized by a dorsal photophore with a single lateral axis on the gladius and fused locking apparatus its distribution includes the Red Sea, the Arabian Sea and the Gulf of Aden northward of approximate 12 º N, to our knowledge a few mature adult females were recorded in the equatorial region of having an ML of 725 and 820 mm, whereas in the Arabian Sea an adult female had an ML of 300 – 500 mm.[4][6][7] The different size forms can be explained by phenotypic plasticity due to environmental conditions.[8]
The species occurs in a diverse range of environments in the tropical and subtropical Indo-Pacific, at depths from the surface to more than 600 m (1,969 ft) deep.[9][6][7] Total species biomass has been estimated at between 8 – 11 million tonnes; the Arabian Sea from November to January is thought to have one of the highest concentrations (12 to 42 t km−2) due to population dynamics.[3]
Purpleback flying squids, which are thought to be both predators and prey, are considered both because throughout their life they are constantly changing, with continuous body-size increases allowing them to fulfill different trophic levels on the taxonomic and ecological spectrum in consideration of their food organisms, enemies and parasites.[6] They feed utilizing a beak, which is a hard structure that contains composites of proteins and chitin fibres.[10] Beaks are an important morphological characteristic; they can be used to identify and classify a species as they are easy to see with the naked eye and do not break down in the stomachs of predators.[10] This feeding organ tears up and bites food, and throughout the squid's life, the characteristics of a beak can change as a result of ontogenetic states.[10] The wing of the beak undergoes pigmentation that is related to the stiffness or hardness of the beak; the more tanned regions are harder than the untanned regions, and this pigmentation is directly linked with growth and changes in the diet.[10]
Purpleback flying squids are highly active predators that can move through the water at high speeds, easily manoeuvre and respond swiftly to changes in their environment.[6] When under distress from external factors such as predation, they can reach a high speed and glide above the surface over ten meters; the cruising speed of an adult squid is between 3 and 10 km per hour, whereas their burst speed can reach 35 km per hour. Burst speed can be important for sudden changes in movement and escape behaviour.[6] They can gather into shoals ranging in size from two to 800 individuals, and in some cases in which geographical distributions overlap, they can travel within similar-sized schools of Dosidicus gigas and Ommastrephes bartramii.[9]
The diet of purpleback flying squids depends on their mantle length; young squids or paralarva tend to feed predominately on mesozooplankton and mesozooplankton, which include copepods, amphipods and many others.[6] Juveniles or post-paralarvae can feed on mesoplanktonic and macroplanktonic invertebrates, which mainly include copepods, euphausiids, amphipods and chaetognaths, as well as micronekton fishes (mainly myctophids) and squids, as their mantle length cane range between 10 and 80 mm.[6] As they grow larger, their preference shifts toward larger fishes and squids and even other purpleback flying squids, as cannibalism is fairly common in this species.[6]
Purpleback flying squids are predated upon by many species throughout their life as they increase in size.[6] Paralarvae and juveniles are usually eaten by larger animals that include chaetognaths, jellyfishes, small squids, planktivorous and small carnivores teleosts.[6] Juveniles that have a mantle lengths of 3 to 12 mm are preyed on by large Humboldt squids Dosidicus gigas, dolphinfishes Coryphaena hippurus, C. equisetis, the snake mackerel Gempylus serpens, the lancet fish Alepisaurus ferox and many species of tuna.[6] Many species of sea birds also predate on juvenile and smaller squids in oceanic regional islands.[6] The predators of the medium- to large-sized purpleback squids include swordfishes Xiphias gladis, striped marlins Tetrapterus audax, many species of different sharks (for instance, the blue shark Prionace glauca), the dusky shark Carcharhinus obscurus, the oceanic whitetip shark Carcharhinus logimanus, the silky shark Carcharhinus falciformis, the smooth hammerhead shark Sphyrna zyganea, the sperm whale Physeter macrocephalus and the Galapagos fur seal Arctocephalus galapagoensis.[6]
Purpleback squids are thought to have a lifespan of up to one year, but the lifespan of much larger squids is unknown.[6][11] The purpleback squid's spawning method is characteristic of the subfamily Ommastrephinae.[6] S. oualaniensis is a monocyclic r-strategist, and the potential fecundity is dependent on the form type of the squid, which can range from 0.3 to 22 million.[6]
The purpleback squid exhibits no premating rituals, as its overall mating system tends to be polygynous to polyandrous.[6] Mating occurs in the surface waters at night where the squids mate in the “male-parallel” or the “head-to-head” positions to increase the likelihood of successful mating.[6] The overall duration of mating is short, lasting up to two minutes. Successful copulations can produce up to 150 spermatangia, which are then attached to the buccal cone and the membrane of the females.[6] Specific to this species are year-round spawning periods that can last up to three months for female squids.[6] The peak season is also dependent on the form type of the squid. Spawning takes place near the epipelagic zone at night, while spawning occurs in intervals (up to 10 cycles) rather than in continuous time, and multiple batches can occur within one spawning period.[6]
After spawning is completed, the large, pelagic, gelatinous egg masses will float to the surface above the upper pycnocline layer./ The females will remain to feed and grow while the remaining oocytes are matured and the next spawning interval begins.[6] The duration of embryonic development is dependent on water temperature.[6] For example, if development occurs at a water temperature of 25 °C, it takes approximately three to six days.[6] The egg size can range from 0.75 to 0.9 mm, and the hatchling size has a mantle length of approximately 1.0 mm.[6]
Purpleback squids are among the fastest-growing squid species, as the daily increase of overall length in the dwarf and middle-sized forms is about 1.0 mm; for the giant form, it is about 3.8 mm.[6]
When embryonic development is complete, it is characterized by a paralarval stage that is unique to octopuses and squids. The paralarva is also known as the rhynchoteuthion stage, which is identified by the tentacles fusing to form a trunk-like proboscis with a few suckers on the distal tip.[6] When this stage is completed, it is signified by a separation of approximately 7.0 to 8.0 mm in mantle length.[6]
The purpleback flying squid or purpleback squid (Sthenoteuthis oualaniensis) is a species of cephalopod in the family Ommastrephidae, occurring in the Indo-Pacific. It is considered one of the most abundant large squids.
Sthenoteuthis oualaniensis, l'encornet bande violette[1] est une espèce de mollusque céphalopode de la famille des Ommastrephidae, le calmar probablement le plus commun du bassin indo-pacifique. Il fait partie des espèces souvent désignées sous le nom japonais de tobiika, littéralement «calmar volant».
L'épithète spécifique “oualaniensis” fait référence à l'île d'Oualan, actuellement connue sous le nom de Kosrae, l'une des îles-état de la Micronésie.
Il existe plusieurs formes de cette espèce. La plus répandue, présente sur toute l'aire de répartition, est de taille moyenne, avec des individus matures dont le manteau mesure de 12 à 15 cm chez les mâles et de 19 à 25 cm chez les femelles. Elle est caractérisée par une bande dorsale violette et la présence en position dorsale antérieure d'une zone bioluminescente de forme ronde de concentration de photophores. Une forme “géante” dont le manteau peut atteindre 65 cm fréquente les abords de la péninsule Arabique et une forme “naine” avec un manteau dépourvu de photophore qui ne dépasse pas 15 cm de long se rencontre dans la zone équatoriale[2].
Chaque individu vit au maximum un an. Lorsque la taille de maturité sexuelle est atteinte la production de gamètes devient continue. Comme la reproduction de l'espèce n'est pas synchrone, on peut trouver à toutes époques des larves, des immatures ou des adultes (avec cependant des optima saisonniers). Sthenoteuthis oualaniensis effectue quotidiennement une migration verticale de plusieurs centaines de mètres pour venir se nourrir près de la surface pendant la nuit. Il constitue une proie d'importance pour certains oiseaux marins et pour les diverses espèces de thons.
Il n'est pas spécialement recherché pour la consommation humaine, ou seulement à titre occasionnel et secondaire, car sa chair est assez grossière. On le pêche néanmoins traditionnellement à Okinawa et Taiwan pour servir d'appât à la pêche aux thonidés.
Sthenoteuthis oualaniensis, l'encornet bande violette est une espèce de mollusque céphalopode de la famille des Ommastrephidae, le calmar probablement le plus commun du bassin indo-pacifique. Il fait partie des espèces souvent désignées sous le nom japonais de tobiika, littéralement «calmar volant».
L'épithète spécifique “oualaniensis” fait référence à l'île d'Oualan, actuellement connue sous le nom de Kosrae, l'une des îles-état de la Micronésie.
Il existe plusieurs formes de cette espèce. La plus répandue, présente sur toute l'aire de répartition, est de taille moyenne, avec des individus matures dont le manteau mesure de 12 à 15 cm chez les mâles et de 19 à 25 cm chez les femelles. Elle est caractérisée par une bande dorsale violette et la présence en position dorsale antérieure d'une zone bioluminescente de forme ronde de concentration de photophores. Une forme “géante” dont le manteau peut atteindre 65 cm fréquente les abords de la péninsule Arabique et une forme “naine” avec un manteau dépourvu de photophore qui ne dépasse pas 15 cm de long se rencontre dans la zone équatoriale.
Chaque individu vit au maximum un an. Lorsque la taille de maturité sexuelle est atteinte la production de gamètes devient continue. Comme la reproduction de l'espèce n'est pas synchrone, on peut trouver à toutes époques des larves, des immatures ou des adultes (avec cependant des optima saisonniers). Sthenoteuthis oualaniensis effectue quotidiennement une migration verticale de plusieurs centaines de mètres pour venir se nourrir près de la surface pendant la nuit. Il constitue une proie d'importance pour certains oiseaux marins et pour les diverses espèces de thons.
Il n'est pas spécialement recherché pour la consommation humaine, ou seulement à titre occasionnel et secondaire, car sa chair est assez grossière. On le pêche néanmoins traditionnellement à Okinawa et Taiwan pour servir d'appât à la pêche aux thonidés.
Sthenoteuthis oualaniensis is een soort in de taxonomische indeling van de inktvissen, een klasse dieren die tot de stam der weekdieren (Mollusca) behoort. De inktvis komt enkel in zout water voor en is in staat om van kleur te veranderen. Hij beweegt zich voort door water in zijn mantel te pompen en het er via de sifon weer krachtig uit te persen. De inktvis is een carnivoor en zijn voedsel bestaat voornamelijk uit vis, krabben, kreeften en weekdieren die ze met de zuignappen op hun grijparmen vangen.
De inktvis komt uit het geslacht Sthenoteuthis en behoort tot de familie Ommastrephidae. Sthenoteuthis oualaniensis werd in 1830 beschreven door Lesson.[1]
Bronnen, noten en/of referentiesMực xà hay còn gọi là mực ma (danh pháp hai phần: Sthenoteuthis oualaniensis) là loài nhuyễn thể chân đầu thuộc ngành động vật thân mềm phân bố ở một số địa phương duyên hải miền Trung Việt Nam như Đà Nẵng, Quảng Nam, Quảng Ngãi, Bình Định, Phú Yên… và có nhiều ở vùng biển Hoàng Sa, Trường Sa.[1]
Đuôi mực xà có màu đen sậm, dày, xòe to như đuôi cá.[2] Mực xà sau khi phơi khô có vị hơi đắng, không ngon, ngọt và mềm như loại mực khô thông thường, mực xà ăn được, nhưng không ngon (vị hơi chát, cứng, khó nhai) nên ít dùng. Mực xà Hoàng Sa có đặc điểm phơi khô lên có màu hơi đen, vị hơi nhẫn, thị trường trong nước không chuộng vì chế biến không tốt[3]
Mực xà được ngư dân Việt Nam đánh bắt ở khu vực Trường Sa, phơi khô trên tàu. Giá mực xà khô bán sỉ dao động từ 100.000 - 150.000 đồng/kg, tùy theo loại lớn nhỏ.[1] Nghề câu mực xà thường cách bờ trên 150 hải lý với độ sâu trên 800 m nước, thời gian đánh bắg từ giữa tháng 12 đến cuối tháng 9 năm sau. Nghề câu mực xà xuất hiện từ những năm 1990, lúc đầu phương tiện đánh bắt còn nhỏ, sản lượng đánh bắt và hiệu quả sản xuất còn thấp, nay đã có cải thiện.[4] riêng ở Đà Nẵng, toàn thành phố Đà Nẵng đã có 04/14 tàu khai thác nghề câu mực xà đại dương đi khai thác.[5]
Nhiều người sử dụng mực xà để làm khô mực, loại này khi nướng ăn, thì có vị không giống mực thường dùng. Mực xà sau khi phơi khô có vị hơi đắng, không ngon, ngọt và mềm như loại mực khô thông thường. cách phân biệt mực xà và mực thông thường là phần đuôi. Đuôi mực xà có màu đen sậm, dày, xòe to như đuôi cá, còn đuôi mực ống mỏng, ôm sát vào thân. Mực xà ăn được, nhưng không ngon nên ngư dân ít dùng. Mực xà ăn được, không gây ảnh hưởng đến sức khỏe con người[6] ở miền Bắc Việt Nam có đội thuyền chuyên đi câu mực xà ở vùng biển xa bờ, phơi khô và xuất bán sang Trung Quốc qua đường tiểu ngạch, chủ yếu bán cho thương lái Trung Quốc qua đường tiểu ngạch ở biên giới phía Bắc.[6]
Mực xà hay còn gọi là mực ma (danh pháp hai phần: Sthenoteuthis oualaniensis) là loài nhuyễn thể chân đầu thuộc ngành động vật thân mềm phân bố ở một số địa phương duyên hải miền Trung Việt Nam như Đà Nẵng, Quảng Nam, Quảng Ngãi, Bình Định, Phú Yên… và có nhiều ở vùng biển Hoàng Sa, Trường Sa.
奧蘭鳶魷（学名：Sthenoteuthis oualaniensis），又名南魷、鳶烏賊，为柔魚科強力柔魚屬下的一个种。
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