La mantellina, rajada papallona o vela llatina (Gymnura altavela) és una rajada que té forma de disc ròmbic i que es pot trobar a llocs com la Mar Mediterrània i l'oest i l'est de l'Oceà Atlàntic.
És ovípar, la gestació dura uns 6 mesos i sol tenir entre 4 i 8 cries.
Es nodreix de peixos, crustacis i mol·luscs.
Habita principalment aigües costaneres no molt fondes (60 m) amb fons suaus, sorrencs o fangosos.
Es distribueix per l'oest de l'Oceà Atlàntic (els Estats Units, el Brasil i l'Argentina), l'Atlàntic oriental (Portugal, Angola, les Illes Canàries), la Mar Mediterrània i la Mar Negra.
Es troba en un estat de conservació molt vulnerable i no acostuma a ésser capturat.
La mantellina, rajada papallona o vela llatina (Gymnura altavela) és una rajada que té forma de disc ròmbic i que es pot trobar a llocs com la Mar Mediterrània i l'oest i l'est de l'Oceà Atlàntic.
The spiny butterfly ray or giant butterfly ray (Gymnura altavela) is a species of butterfly ray, family Gymnuridae, native to the shallow coastal waters of the Atlantic Ocean. A large ray that can measure over 2 m (6 ft 7 in) across, it may be distinguished from the sympatric smooth butterfly ray (G. micrura) by the spine at the base of its tail and by a small tentacular structure on the margin of each spiracle. Slow-reproducing and valued for its meat, in recent decades its population has experienced a decline of over 30%, and it has become Critically Endangered in certain parts of its range.[1]
This species has a patchy and discontinuous distribution in Atlantic tropical and warm-temperate waters. In the western Atlantic it is found from Massachusetts, United States to Buenos Aires Province, Argentina; it is rare in the Gulf of Mexico and common in the mouths of tidal creeks along the Virginia coast. In the eastern Atlantic, it is found from Portugal to Angola, including Madeira and the Canary Islands.[1] It is also recorded in the Mediterranean and Black Seas.[2] It is found in shallow brackish and coastal waters over soft sandy or muddy substrates, at a depth of 5–100 m (16–328 ft).[3] This ray is uncommon overall but can be locally abundant in suitable habitat.[1] Individuals may segregate by sex, with females usually staying in deeper water but moving inshore to breed.[4]
The spiny butterfly ray has a very broad, lozenge-shaped pectoral fin disk much wider than it is long, with concave front margins and abruptly rounded corners. The snout is short and blunt. The teeth have high, conical cusps, numbering 98–138 rows in the upper jaw and 78–110 rows in the lower jaw. In both jaws there are 10–12 functional tooth rows with each dental band occupying 70% the width of the jaw. There is a tentacle-like structure on the inner posterior margin of each spiracle. The tail is short and slender, measuring a quarter the disk width, with upper and lower fin folds. There are one or more serrated spines at the base of the tail.[3][5]
The skin is naked in juveniles and subadults, while adults develop a patch of denticles on the center of the disk.[5] The coloration is dark brown above, sometimes with small lighter or darker spots and blotches in a marbled pattern, and white below. Juveniles have pale crossbars on the tail.[3] The maximum reported size is 2.2 m (7 ft 3 in) disk width in the northwest Atlantic, though there are unsubstantiated reports of rays over 4 m (13 ft) off West Africa.[1] The maximum published weight is 60 kg (130 lb).[6]
In the western Atlantic, the spiny butterfly ray feeds on fishes, including Leiognathus and small sharks, and squids. Off Tunisia, they feed on crustaceans, teleosts, cephalopods, lamellibranchs, and gastropods, in descending order of importance. Teleost fishes apparently become more important in the ray's diet with increasing size. An active predator, the ray typically approaches a prey item slowly before rapidly spinning around over it and striking the food with the leading edge of one of their pectoral fins. This behavior likely serves to stun the prey before capture, as the pectoral fins of butterfly rays contain a high proportion of red muscle and can deliver blows of substantial force.[7][8]
Potential predators of spiny butterfly rays include larger fish such as the great hammerhead (Sphyrna mokarran), and marine mammals.[3] In the northwest Atlantic, the depletion of seven large shark species by commercial fisheries has led to an increase in the population of the spiny butterfly ray and other mid-level predators.[9] Known parasites of this species include the tapeworms Anthobothrium altavelae and Pterobothrioides petterae, and the gill parasite Heteronchocotyle gymnurae.[3][10][11]
Spiny butterfly rays are ovoviviparous and give birth to live young. They have an annual reproductive cycle with a gestation period of 4 to 9 months. The embryos initially subsist on a yolk sac; later in development long villi develop from the uterine wall into the embryos' spiracles, which direct uterine milk into the oral cavity.[12] Litter size is up to 8, depending on geographical location: 4 per litter in the Gulf of Mexico, 1–6 in the Mediterranean, up to 5 off Brazil, and up to 8 in the northwest Atlantic. Females have one functional ovary (the left) and two functional uteruses, with the embryos evenly distributed in each one. The newborns measure 38–44 cm (15–17 in) across; their size is inversely related to the number of young in each uterus.[1][8] In the eastern Atlantic, males mature at around 78 cm (31 in) across and females at 108 cm (43 in). In the western Atlantic, males mature at around 102 cm (40 in) across and females at 155 cm (61 in).[7] Females mature later than males and reach a larger size.[4]
Spiny butterfly rays are harmless to humans, though if stepped on its tail spine can cause a painful wound. It is listed as a game fish in some regions.[3] The meat of this species is highly regarded and it is caught for human consumption, except for in the waters off the United States where it is not targeted by commercial fisheries and is rarely taken as bycatch. It is assessed as Endangered by the World Conservation Union.[1]
Elsewhere in the spiny butterfly ray's range, it faces heavy fishing pressure, including in its coastal nursery areas, and has experienced marked declines. It is assessed as Critically Endangered in the southwest Atlantic, where it is taken by multispecies trawls, beach-seines, and recreational fishers. Off southern Brazil, catch rates have declined by 99% since 1982, due to fishing occurring year-round. This species is also Critically Endangered in the Mediterranean, where it is now rare or absent throughout its entire former range, especially along the southern shore such as off Sicily. The comprehensive Mediterranean International Trawl Surveys (MITS) since 1994 have failed to recover any specimens, indicating a massive decline in numbers. In West Africa, this species is assessed as Vulnerable; it is taken intentionally or incidentally by gillnets, shrimp trawls, longlines, and handlines. Reports from artisan fishers and other observers from Mauritania to Guinea have reported a severe drop in abundance, as well as decreasing median size as the adults are removed.[1]
{{cite journal}}: CS1 maint: multiple names: authors list (link) The spiny butterfly ray or giant butterfly ray (Gymnura altavela) is a species of butterfly ray, family Gymnuridae, native to the shallow coastal waters of the Atlantic Ocean. A large ray that can measure over 2 m (6 ft 7 in) across, it may be distinguished from the sympatric smooth butterfly ray (G. micrura) by the spine at the base of its tail and by a small tentacular structure on the margin of each spiracle. Slow-reproducing and valued for its meat, in recent decades its population has experienced a decline of over 30%, and it has become Critically Endangered in certain parts of its range.
Gymnura altavela Gymnura generoko animalia da. Arrainen barruko Gymnuridae familian sailkatzen da.
Gymnura altavela Gymnura generoko animalia da. Arrainen barruko Gymnuridae familian sailkatzen da.
Piikkiperhosrausku (Gymnura altavela) on perhosrauskujen heimoon kuuluva rustokalalaji.[1] Lajin kuvasi Carl von Linné vuonna 1758.
Piikkiperhosrausku kasvaa yleensä noin kahden, joskus jopa neljän metrin mittaiseksi.[1]
Lajia tavataan Afrikasta, Aasiasta, Euroopasta ja Pohjois-Amerikasta.[2] Perhospiikkirauskun uhanalaisuusluokitus on Kansainvälisen luonnonsuojeluliiton mukaan vaarantunut.[3]
Piikkiperhosrausku (Gymnura altavela) on perhosrauskujen heimoon kuuluva rustokalalaji. Lajin kuvasi Carl von Linné vuonna 1758.
Gymnura altavela est une espèce de raies de la famille des Gymnuridae. Elle est parfois appelée « raie-papillon » ou « pastenague ailée »[1].
Gymnura altavela fréquente les eaux chaudes et tempérées de l'Atlantique et de la Méditerranée.
Gymnura altavela est inoffensive pour l'homme. Cette espèce est considérée comme prise de choix pour la pêche sportive dans certaines régions[1],[2],[3].
Gymnura altavela est une espèce de raies de la famille des Gymnuridae. Elle est parfois appelée « raie-papillon » ou « pastenague ailée ».
Gymnura altavela (Linnaeus, 1758)[2], comunemente chiamato altavela è un pesce raiforme appartenente alla famiglia Gymnuridae. Si tratta del rappresentante di maggiori dimensioni del genere Gymnura, raggiungendo un'ampiezza massima del disco di 4 metri[3].
Vive nelle acque costiere tropicali e subtropicali dell'Atlantico, con una distribuzione tendenzialmente non uniforme. Sul lato occidentale, andando da nord a sud, la si ritrova dalle coste del Massachusetts fino al Rio della Plata in Argentina, mentre dal lato orientale si spinge a nord fino alle coste settentrionali del Portogallo, ed a sud fino all'Angola[4]. La sua presenza era un tempo segnalata in tutto il Mar Mediterraneo, compreso il mar Nero, mentre al giorno d'oggi è ristretta al bacino meridionale.
Frequenta abitualmente acque poco profonde, tra i 5 ed i 100 metri, sui fondali sabbiosi o melmosi, spingendosi anche molto vicino a riva[3].
Il corpo dell'altavela è costituito da un disco fortemente compresso a forma di aquilone largo circa due volte la sua lunghezza. Il muso presenta un brevissimo rostro. Gli occhi sono piccoli e seguiti dai due spiracoli, dotati di una modesta appendice peduncolata. Sul ventre si aprono bilateralmente le cinque fessure branchiali, di piccole dimensioni, e più anteriormente la bocca, quasi rettilinea, dotata di 98-138 denti nell'arcata mascellare e 78-110 su quella mandibolare, disposti in 10-12 file[5]. Posteriormente si diparte un'appendice caudale piuttosto breve, lunga circa un quarto del disco, sormontata alla base da una o due spine parzialmente seghettate[6].
La colorazione sul dorso varia tra il bruno ed il grigio marezzato, mentre sul lato ventrale è lattescente.
La massima larghezza del disco ufficialmente registrata è stata di 4 metri, ed un peso di 60 kg[5].
Frequenta abitualmente fondali sabbiosi o melmosi, dove può proteggersi più facilmente, seppellendosi e lasciando sporgere fuori solo gli occhi ed i due spiracoli. La caratteristica impronta lasciata dal corpo può essere osservata anche molto tempo dopo il suo spostamento[7]. Malgrado la presenza di spine velenifere, non è considerata pericolosa per l'uomo.
Essendo animale prettamente bentonico, l'altavela si nutre di piccoli pesci e crostacei, molluschi ed altre creature di fondo di piccole dimensioni. Per la caccia utilizza le sue ampie pinne pettorali per colpire e stordire le prede, prima di inghiottirle[8].
Si tratta di una specie ovovivipara sprovvista di placenta: le uova si schiudono all'interno dell'utero, dove prosegue lo sviluppo embrionale, durante il quale il sostentamento viene fornito direttamente dalle componenti del fluido intrauterino[9]. La gestazione dura circa 6 mesi e nascono un numero variabile di piccoli, da 2 a 6[10].
Le sue carni sono apprezzate in alcun località e per questo viene pescata soprattutto nelle aree meridionali del Mediterraneo e sulle coste del Brasile. Pur non essendo una specie facilmente adattabile alla vita in cattività, si è riusciti a farla ambientare in alcuni acquari di grandi dimensioni[11].
Il basso tasso di riproduzione e la pressione dovuta alla pesca hanno inciso sensibilmente su questa specie, che è stata inserita nella lista IUCN tra le specie vulnerabili (VU). In particolare in tutto il Mediterraneo ed in Brasile, dove una volta era segnalata con frequenza, è diventata decisamente rara, tanto che il suo status locale è stato elevato a critico (CR)[1].
Gymnura altavela (Linnaeus, 1758), comunemente chiamato altavela è un pesce raiforme appartenente alla famiglia Gymnuridae. Si tratta del rappresentante di maggiori dimensioni del genere Gymnura, raggiungendo un'ampiezza massima del disco di 4 metri.
Gymnura altavela is een vissensoort uit de familie van de vlinderroggen (Gymnuridae).[1] De wetenschappelijke naam van de soort is voor het eerst geldig gepubliceerd in 1758 door Linnaeus.
Bronnen, noten en/of referenties
A Raia-borboleta (nome científico: Gymnura altavela) é uma espécie de raia na família Gymnuridae. Mede de 1 a 2 m de comprimento e nada de 1 aos 70 metros de profundidade. É nativa do Oceano Atlântico.[1]
A Raia-borboleta (nome científico: Gymnura altavela) é uma espécie de raia na família Gymnuridae. Mede de 1 a 2 m de comprimento e nada de 1 aos 70 metros de profundidade. É nativa do Oceano Atlântico.
Атлантические скаты-бабочки используют шип, расположенный на хвостовом стебле для защиты. В западной Атлантике они охотятся на костистых рыб, в первую очередь сребробрюшковыхruen, мелких акул и кальмаров. У берегов Туниса атлантические скаты-бабочки питаются ракообразными, костистыми рыбами, головоногими, двустворчатыми и брюхоногими (перечислено в порядке убывания важности компонента в рационе). По мере роста скатов доля костистых рыб в их рационе увеличивается. Будучи активными хищниками скаты-бабочки медленно подплывают к добыче, затем резко оборачиваются вокруг неё и бьют передним краем грудных плавников. Мощные красные мышцы грудных плавников позволяют нанести сильный удар и оглушить жертву перед поимкой[11][10].
В свою очередь атлантические скаты-бабочки могут стать добычей крупных рыб, например гигантской акулы-молота, и морских млекопитающих[5]. В северо-западной части Атлантического океана чрезмерный вылов крупных акул привёл к увеличению численности атлантических скатов-бабочек и прочих хищников средней ниши[12]. На этом виде скатов паразитируют ленточные черви Anthobothrium altavelae and Pterobothrioides petterae и моногенеи Heteronchocotyle gymnurae[5][13][14].
Атлантические скаты-бабочки обычно не представляют опасности для человека, однако, если на них случайно наступить, они могут нанести болезненный укол хвостовым шипом. В некоторых местах они представляют интерес для рыболовов-любителей[3]. Их мясо высоко ценится, они являются объектом коммерческого и кустарного промысла по всему ареалу за исключением вод США, где их не промышляют. В юго-западной Атлантике их ловят тралами, неводами и на крючок. У южного побережья Бразилии с 1982 года численность популяции атлантических скатов-бабочек сократилась на 99 % из-за круглогодичного лова. Международный союз охраны природы присвоил этому виду статус «Уязвимый»[3].
Атлантические скаты-бабочки используют шип, расположенный на хвостовом стебле для защиты. В западной Атлантике они охотятся на костистых рыб, в первую очередь сребробрюшковыхruen, мелких акул и кальмаров. У берегов Туниса атлантические скаты-бабочки питаются ракообразными, костистыми рыбами, головоногими, двустворчатыми и брюхоногими (перечислено в порядке убывания важности компонента в рационе). По мере роста скатов доля костистых рыб в их рационе увеличивается. Будучи активными хищниками скаты-бабочки медленно подплывают к добыче, затем резко оборачиваются вокруг неё и бьют передним краем грудных плавников. Мощные красные мышцы грудных плавников позволяют нанести сильный удар и оглушить жертву перед поимкой.
В свою очередь атлантические скаты-бабочки могут стать добычей крупных рыб, например гигантской акулы-молота, и морских млекопитающих. В северо-западной части Атлантического океана чрезмерный вылов крупных акул привёл к увеличению численности атлантических скатов-бабочек и прочих хищников средней ниши. На этом виде скатов паразитируют ленточные черви Anthobothrium altavelae and Pterobothrioides petterae и моногенеи Heteronchocotyle gymnurae.
